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SubjectRe: [RFC][PATCH] iowait statistics
On Mon, 13 May 2002, Rik van Riel wrote:

> Hi,
>
> the following patch implements iowait statistics in a simple way:

This follows some work I was doing back in 2.4.10 or so WRT just measuring
the delay caused by waiting for page IO. Attached is a patch against
2.4.19-pre8-ac3 which is the offspring of preempt-kernel and Rik's waitio
patch. All I can claim is that it still runs and boots, seems to have
working preempt, and returns reasonable numbers for iowait on a uni
processor. I intend to test more, but I know that this is a popular ac
version, and hopefully this will be useful.

Until I try this on a real machine and see what tuning of things like
hdparm and elvtune do, test rmap again -aa, etc, this is an exercise in
getting it to work. I'd be interested in feedback, and I hope Rik will
continue his development.

--
bill davidsen <davidsen@tmr.com>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.
*** ./Makefile Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./Makefile Tue May 14 17:01:49 2002
***************
*** 1,7 ****
VERSION = 2
PATCHLEVEL = 4
SUBLEVEL = 19
! EXTRAVERSION = -pre8-ac3

KERNELRELEASE=$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)

--- 1,7 ----
VERSION = 2
PATCHLEVEL = 4
SUBLEVEL = 19
! EXTRAVERSION = -pre8-ac3.1p+iow

KERNELRELEASE=$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)

*** ./fs/buffer.c Tue May 14 14:59:19 2002
--- ../linux-2.4.19-pre8-ac3p/./fs/buffer.c Tue May 14 16:43:04 2002
***************
*** 154,164 ****
--- 154,166 ----
get_bh(bh);
add_wait_queue(&bh->b_wait, &wait);
do {
+ atomic_inc(&nr_iowait_tasks);
run_task_queue(&tq_disk);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (!buffer_locked(bh))
break;
schedule();
+ atomic_dec(&nr_iowait_tasks);
} while (buffer_locked(bh));
tsk->state = TASK_RUNNING;
remove_wait_queue(&bh->b_wait, &wait);
*** ./fs/exec.c Tue May 14 14:59:19 2002
--- ../linux-2.4.19-pre8-ac3p/./fs/exec.c Tue May 14 15:09:17 2002
***************
*** 427,434 ****
active_mm = current->active_mm;
current->mm = mm;
current->active_mm = mm;
- task_unlock(current);
activate_mm(active_mm, mm);
mm_release();
if (old_mm) {
if (active_mm != old_mm) BUG();
--- 427,434 ----
active_mm = current->active_mm;
current->mm = mm;
current->active_mm = mm;
activate_mm(active_mm, mm);
+ task_unlock(current);
mm_release();
if (old_mm) {
if (active_mm != old_mm) BUG();
*** ./fs/proc/proc_misc.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./fs/proc/proc_misc.c Tue May 14 16:48:00 2002
***************
*** 273,279 ****
int i, len;
extern unsigned long total_forks;
unsigned long jif = jiffies;
! unsigned int sum = 0, user = 0, nice = 0, system = 0;
int major, disk;

for (i = 0 ; i < smp_num_cpus; i++) {
--- 273,279 ----
int i, len;
extern unsigned long total_forks;
unsigned long jif = jiffies;
! unsigned int sum = 0, user = 0, nice = 0, system = 0, iowait = 0;
int major, disk;

for (i = 0 ; i < smp_num_cpus; i++) {
***************
*** 282,304 ****
user += kstat.per_cpu_user[cpu];
nice += kstat.per_cpu_nice[cpu];
system += kstat.per_cpu_system[cpu];
#if !defined(CONFIG_ARCH_S390)
for (j = 0 ; j < NR_IRQS ; j++)
sum += kstat.irqs[cpu][j];
#endif
}

! len = sprintf(page, "cpu %u %u %u %lu\n", user, nice, system,
! jif * smp_num_cpus - (user + nice + system));
for (i = 0 ; i < smp_num_cpus; i++)
! len += sprintf(page + len, "cpu%d %u %u %u %lu\n",
i,
kstat.per_cpu_user[cpu_logical_map(i)],
kstat.per_cpu_nice[cpu_logical_map(i)],
kstat.per_cpu_system[cpu_logical_map(i)],
jif - ( kstat.per_cpu_user[cpu_logical_map(i)] \
+ kstat.per_cpu_nice[cpu_logical_map(i)] \
! + kstat.per_cpu_system[cpu_logical_map(i)]));
len += sprintf(page + len,
"page %u %u\n"
"swap %u %u\n"
--- 282,307 ----
user += kstat.per_cpu_user[cpu];
nice += kstat.per_cpu_nice[cpu];
system += kstat.per_cpu_system[cpu];
+ iowait += kstat.per_cpu_iowait[cpu];
#if !defined(CONFIG_ARCH_S390)
for (j = 0 ; j < NR_IRQS ; j++)
sum += kstat.irqs[cpu][j];
#endif
}

! len = sprintf(page, "cpu %u %u %u %lu %u\n", user, nice, system,
! jif * smp_num_cpus - (user + nice + system),
! iowait);
for (i = 0 ; i < smp_num_cpus; i++)
! len += sprintf(page + len, "cpu%d %u %u %u %lu %u\n",
i,
kstat.per_cpu_user[cpu_logical_map(i)],
kstat.per_cpu_nice[cpu_logical_map(i)],
kstat.per_cpu_system[cpu_logical_map(i)],
jif - ( kstat.per_cpu_user[cpu_logical_map(i)] \
+ kstat.per_cpu_nice[cpu_logical_map(i)] \
! + kstat.per_cpu_system[cpu_logical_map(i)]),
! kstat.per_cpu_iowait[cpu_logical_map(i)]);
len += sprintf(page + len,
"page %u %u\n"
"swap %u %u\n"
*** ./fs/fat/cache.c Fri Oct 12 16:48:42 2001
--- ../linux-2.4.19-pre8-ac3p/./fs/fat/cache.c Tue May 14 15:09:17 2002
***************
*** 14,19 ****
--- 14,20 ----
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/fat_cvf.h>
+ #include <linux/sched.h>

#if 0
# define PRINTK(x) printk x
*** ./fs/nls/nls_base.c Tue May 14 14:55:54 2002
--- ../linux-2.4.19-pre8-ac3p/./fs/nls/nls_base.c Tue May 14 15:09:18 2002
***************
*** 18,23 ****
--- 18,24 ----
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif
+ #include <linux/sched.h>
#include <linux/spinlock.h>

static struct nls_table *tables;
*** ./fs/adfs/map.c Thu Oct 25 16:53:53 2001
--- ../linux-2.4.19-pre8-ac3p/./fs/adfs/map.c Tue May 14 15:09:17 2002
***************
*** 12,17 ****
--- 12,18 ----
#include <linux/fs.h>
#include <linux/adfs_fs.h>
#include <linux/spinlock.h>
+ #include <linux/sched.h>

#include "adfs.h"

*** ./kernel/sched.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./kernel/sched.c Tue May 14 15:09:18 2002
***************
*** 165,174 ****
--- 165,176 ----
struct runqueue *rq;

repeat_lock_task:
+ preempt_disable();
rq = task_rq(p);
spin_lock_irqsave(&rq->lock, *flags);
if (unlikely(rq != task_rq(p))) {
spin_unlock_irqrestore(&rq->lock, *flags);
+ preempt_enable();
goto repeat_lock_task;
}
return rq;
***************
*** 177,182 ****
--- 179,185 ----
static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
{
spin_unlock_irqrestore(&rq->lock, *flags);
+ preempt_enable();
}

/*
***************
*** 257,267 ****
--- 260,272 ----
{
int need_resched;

+ preempt_disable();
need_resched = p->need_resched;
wmb();
set_tsk_need_resched(p);
if (!need_resched && (p->cpu != smp_processor_id()))
smp_send_reschedule(p->cpu);
+ preempt_enable();
}

#ifdef CONFIG_SMP
***************
*** 276,281 ****
--- 281,287 ----
runqueue_t *rq;

repeat:
+ preempt_disable();
rq = task_rq(p);
while (unlikely(rq->curr == p)) {
cpu_relax();
***************
*** 284,292 ****
--- 290,300 ----
rq = task_rq_lock(p, &flags);
if (unlikely(rq->curr == p)) {
task_rq_unlock(rq, &flags);
+ preempt_enable();
goto repeat;
}
task_rq_unlock(rq, &flags);
+ preempt_enable();
}

/*
***************
*** 340,345 ****
--- 348,354 ----
{
runqueue_t *rq;

+ preempt_disable();
rq = this_rq();
spin_lock_irq(&rq->lock);

***************
*** 357,362 ****
--- 366,372 ----
p->cpu = smp_processor_id();
activate_task(p, rq);
spin_unlock_irq(&rq->lock);
+ preempt_enable();
}

/*
***************
*** 384,390 ****
p->sleep_avg) / (EXIT_WEIGHT + 1);
}

! #if CONFIG_SMP
asmlinkage void schedule_tail(task_t *prev)
{
spin_unlock_irq(&this_rq()->frozen);
--- 394,400 ----
p->sleep_avg) / (EXIT_WEIGHT + 1);
}

! #if CONFIG_SMP || CONFIG_PREEMPT
asmlinkage void schedule_tail(task_t *prev)
{
spin_unlock_irq(&this_rq()->frozen);
***************
*** 739,744 ****
--- 749,755 ----
BUG_ON(in_interrupt());

need_resched:
+ preempt_disable();
prev = current;
rq = this_rq();

***************
*** 746,751 ****
--- 757,769 ----
prev->sleep_timestamp = jiffies;
spin_lock_irq(&rq->lock);

+ /*
+ * if entering from preempt_schedule, off a kernel preemption,
+ * go straight to picking the next task.
+ */
+ if (unlikely(preempt_get_count() & PREEMPT_ACTIVE))
+ goto pick_next_task;
+
switch (prev->state) {
case TASK_INTERRUPTIBLE:
if (unlikely(signal_pending(prev))) {
***************
*** 757,765 ****
case TASK_RUNNING:
;
}
- #if CONFIG_SMP
pick_next_task:
- #endif
if (unlikely(!rq->nr_running)) {
#if CONFIG_SMP
load_balance(rq, 1);
--- 775,781 ----
***************
*** 810,820 ****
--- 826,855 ----
}

reacquire_kernel_lock(current);
+ preempt_enable_no_resched();
if (need_resched())
goto need_resched;
return;
}

+ #ifdef CONFIG_PREEMPT
+ /*
+ * this is is the entry point to schedule() from in-kernel preemption.
+ */
+ asmlinkage void preempt_schedule(void)
+ {
+ need_resched:
+ current->preempt_count += PREEMPT_ACTIVE;
+ schedule();
+ current->preempt_count -= PREEMPT_ACTIVE;
+
+ /* we could miss a preemption between schedule() and now */
+ barrier();
+ if (unlikely((current->need_resched)))
+ goto need_resched;
+ }
+ #endif /* CONFIG_PREEMP */
+
/*
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
***************
*** 1192,1197 ****
--- 1227,1233 ----
runqueue_t *rq;
prio_array_t *array;

+ preempt_disable();
rq = this_rq();

/*
***************
*** 1220,1225 ****
--- 1256,1262 ----
__set_bit(current->prio, array->bitmap);
}
spin_unlock(&rq->lock);
+ preempt_enable_no_resched();

schedule();

***************
*** 1424,1429 ****
--- 1461,1469 ----
double_rq_unlock(idle_rq, rq);
set_tsk_need_resched(idle);
__restore_flags(flags);
+
+ /* Set the preempt count _outside_ the spinlocks! */
+ idle->preempt_count = (idle->lock_depth >= 0);
}

extern void init_timervecs(void);
***************
*** 1520,1525 ****
--- 1560,1566 ----
if (!new_mask)
BUG();

+ preempt_disable();
rq = task_rq_lock(p, &flags);
p->cpus_allowed = new_mask;
/*
***************
*** 1528,1534 ****
*/
if (new_mask & (1UL << p->cpu)) {
task_rq_unlock(rq, &flags);
! return;
}

init_MUTEX_LOCKED(&req.sem);
--- 1569,1575 ----
*/
if (new_mask & (1UL << p->cpu)) {
task_rq_unlock(rq, &flags);
! goto out;
}

init_MUTEX_LOCKED(&req.sem);
***************
*** 1538,1543 ****
--- 1579,1586 ----
wake_up_process(rq->migration_thread);

down(&req.sem);
+ out:
+ preempt_enable();
}

static int migration_thread(void * bind_cpu)
***************
*** 1592,1609 ****
cpu_dest = __ffs(p->cpus_allowed);
rq_dest = cpu_rq(cpu_dest);
repeat:
! cpu_src = p->thread_info->cpu;
rq_src = cpu_rq(cpu_src);

local_irq_save(flags);
double_rq_lock(rq_src, rq_dest);
! if (p->thread_info->cpu != cpu_src) {
double_rq_unlock(rq_src, rq_dest);
local_irq_restore(flags);
goto repeat;
}
if (rq_src == rq) {
! p->thread_info->cpu = cpu_dest;
if (p->array) {
deactivate_task(p, rq_src);
activate_task(p, rq_dest);
--- 1635,1652 ----
cpu_dest = __ffs(p->cpus_allowed);
rq_dest = cpu_rq(cpu_dest);
repeat:
! cpu_src = p->cpu;
rq_src = cpu_rq(cpu_src);

local_irq_save(flags);
double_rq_lock(rq_src, rq_dest);
! if (p->cpu != cpu_src) {
double_rq_unlock(rq_src, rq_dest);
local_irq_restore(flags);
goto repeat;
}
if (rq_src == rq) {
! p->cpu = cpu_dest;
if (p->array) {
deactivate_task(p, rq_src);
activate_task(p, rq_dest);
*** ./kernel/exit.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./kernel/exit.c Tue May 14 15:09:18 2002
***************
*** 373,380 ****
/* more a memory barrier than a real lock */
task_lock(tsk);
tsk->mm = NULL;
- task_unlock(tsk);
enter_lazy_tlb(mm, current, smp_processor_id());
mmput(mm);
}
}
--- 373,380 ----
/* more a memory barrier than a real lock */
task_lock(tsk);
tsk->mm = NULL;
enter_lazy_tlb(mm, current, smp_processor_id());
+ task_unlock(tsk);
mmput(mm);
}
}
***************
*** 494,499 ****
--- 494,504 ----
panic("Attempted to kill init!");
tsk->flags |= PF_EXITING;
del_timer_sync(&tsk->real_timer);
+
+ if (unlikely(preempt_get_count()))
+ printk(KERN_ERR "%s[%d] exited with preempt_count %d\n",
+ current->comm, current->pid,
+ preempt_get_count());

fake_volatile:
#ifdef CONFIG_BSD_PROCESS_ACCT
*** ./kernel/fork.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./kernel/fork.c Tue May 14 15:09:18 2002
***************
*** 640,645 ****
--- 640,652 ----
if (p->binfmt && p->binfmt->module)
__MOD_INC_USE_COUNT(p->binfmt->module);

+ #ifdef CONFIG_PREEMPT
+ /*
+ * schedule_tail drops this_rq()->lock so compensate with a count
+ * of 1. Also, we want to start with kernel preemption disabled.
+ */
+ p->preempt_count = 1;
+ #endif
p->did_exec = 0;
p->swappable = 0;
p->state = TASK_UNINTERRUPTIBLE;
*** ./kernel/ksyms.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./kernel/ksyms.c Tue May 14 15:09:18 2002
***************
*** 442,447 ****
--- 442,450 ----
EXPORT_SYMBOL(interruptible_sleep_on);
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
EXPORT_SYMBOL(schedule);
+ #ifdef CONFIG_PREEMPT
+ EXPORT_SYMBOL(preempt_schedule);
+ #endif
EXPORT_SYMBOL(schedule_timeout);
EXPORT_SYMBOL(sys_sched_yield);
EXPORT_SYMBOL(set_user_nice);
*** ./kernel/timer.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./kernel/timer.c Tue May 14 18:42:46 2002
***************
*** 585,590 ****
--- 585,592 ----
{
p->per_cpu_utime[cpu] += user;
p->per_cpu_stime[cpu] += system;
+ if (atomic_read(&nr_iowait_tasks) > 0)
+ kstat.per_cpu_iowait[cpu] += system;
do_process_times(p, user, system);
do_it_virt(p, user);
do_it_prof(p);
*** ./lib/dec_and_lock.c Wed Oct 3 12:11:26 2001
--- ../linux-2.4.19-pre8-ac3p/./lib/dec_and_lock.c Tue May 14 15:09:18 2002
***************
*** 1,5 ****
--- 1,6 ----
#include <linux/module.h>
#include <linux/spinlock.h>
+ #include <linux/sched.h>
#include <asm/atomic.h>

/*
*** ./mm/filemap.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./mm/filemap.c Tue May 14 17:01:27 2002
***************
*** 45,50 ****
--- 45,51 ----
*/

atomic_t page_cache_size = ATOMIC_INIT(0);
+ atomic_t nr_iowait_tasks = ATOMIC_INIT(0);
unsigned int page_hash_bits;
struct page **page_hash_table;

***************
*** 828,835 ****
--- 829,838 ----
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (!PageLocked(page))
break;
+ atomic_inc(&nr_iowait_tasks);
sync_page(page);
schedule();
+ atomic_dec(&nr_iowait_tasks);
} while (PageLocked(page));
__set_task_state(tsk, TASK_RUNNING);
remove_wait_queue(waitqueue, &wait);
***************
*** 875,882 ****
--- 878,887 ----
for (;;) {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (PageLocked(page)) {
+ atomic_inc(&nr_iowait_tasks);
sync_page(page);
schedule();
+ atomic_dec(&nr_iowait_tasks);
}
if (!TryLockPage(page))
break;
*** ./mm/slab.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./mm/slab.c Tue May 14 15:09:18 2002
***************
*** 49,55 ****
* constructors and destructors are called without any locking.
* Several members in kmem_cache_t and slab_t never change, they
* are accessed without any locking.
! * The per-cpu arrays are never accessed from the wrong cpu, no locking.
* The non-constant members are protected with a per-cache irq spinlock.
*
* Further notes from the original documentation:
--- 49,56 ----
* constructors and destructors are called without any locking.
* Several members in kmem_cache_t and slab_t never change, they
* are accessed without any locking.
! * The per-cpu arrays are never accessed from the wrong cpu, no locking,
! * and local interrupts are disabled so slab code is preempt-safe.
* The non-constant members are protected with a per-cache irq spinlock.
*
* Further notes from the original documentation:
*** ./CREDITS Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./CREDITS Tue May 14 15:09:17 2002
***************
*** 996,1003 ****

N: Nigel Gamble
E: nigel@nrg.org
- E: nigel@sgi.com
D: Interrupt-driven printer driver
S: 120 Alley Way
S: Mountain View, California 94040
S: USA
--- 996,1003 ----

N: Nigel Gamble
E: nigel@nrg.org
D: Interrupt-driven printer driver
+ D: Preemptible kernel
S: 120 Alley Way
S: Mountain View, California 94040
S: USA
*** ./include/linux/sched.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/sched.h Tue May 14 18:09:05 2002
***************
*** 91,96 ****
--- 91,97 ----
#define TASK_UNINTERRUPTIBLE 2
#define TASK_ZOMBIE 4
#define TASK_STOPPED 8
+ #define PREEMPT_ACTIVE 0x4000000

#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
***************
*** 156,161 ****
--- 157,165 ----
#define MAX_SCHEDULE_TIMEOUT LONG_MAX
extern signed long FASTCALL(schedule_timeout(signed long timeout));
asmlinkage void schedule(void);
+ #ifdef CONFIG_PREEMPT
+ asmlinkage void preempt_schedule(void);
+ #endif

extern int schedule_task(struct tq_struct *task);
extern void flush_scheduled_tasks(void);
***************
*** 291,297 ****
* offsets of these are hardcoded elsewhere - touch with care
*/
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
! unsigned long flags; /* per process flags, defined below */
int sigpending;
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
--- 295,301 ----
* offsets of these are hardcoded elsewhere - touch with care
*/
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
! int preempt_count; /* 0 => preemptable, <0 => BUG */
int sigpending;
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
***************
*** 317,322 ****
--- 321,327 ----
unsigned long policy;
unsigned long cpus_allowed;
unsigned int time_slice;
+ unsigned long flags;

task_t *next_task, *prev_task;

***************
*** 358,363 ****
--- 363,369 ----
struct tms times;
unsigned long start_time;
long per_cpu_utime[NR_CPUS], per_cpu_stime[NR_CPUS];
+ long per_cpu_iowait[NR_CPUS];
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap;
int swappable:1;
***************
*** 942,947 ****
--- 948,958 ----
{
return unlikely(current->need_resched);
}
+
+ #define _TASK_STRUCT_DEFINED
+ #include <linux/dcache.h>
+ #include <linux/tqueue.h>
+ #include <linux/fs_struct.h>

#endif /* __KERNEL__ */

*** ./include/linux/tqueue.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/tqueue.h Tue May 14 15:20:25 2002
***************
*** 94,99 ****
--- 94,115 ----
extern spinlock_t tqueue_lock;

/*
+ * Call all "bottom halfs" on a given list.
+ */
+
+ extern void __run_task_queue(task_queue *list);
+
+ static inline void run_task_queue(task_queue *list)
+ {
+ if (TQ_ACTIVE(*list))
+ __run_task_queue(list);
+ }
+
+ #endif /* _LINUX_TQUEUE_H */
+
+ #if !defined(_LINUX_TQUEUE_H_INLINES) && defined(_TASK_STRUCT_DEFINED)
+ #define _LINUX_TQUEUE_H_INLINES
+ /*
* Queue a task on a tq. Return non-zero if it was successfully
* added.
*/
***************
*** 109,125 ****
}
return ret;
}
!
! /*
! * Call all "bottom halfs" on a given list.
! */
!
! extern void __run_task_queue(task_queue *list);
!
! static inline void run_task_queue(task_queue *list)
! {
! if (TQ_ACTIVE(*list))
! __run_task_queue(list);
! }
!
! #endif /* _LINUX_TQUEUE_H */
--- 125,128 ----
}
return ret;
}
! #endif
*** ./include/linux/kernel_stat.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/kernel_stat.h Tue May 14 16:49:04 2002
***************
*** 18,24 ****
struct kernel_stat {
unsigned int per_cpu_user[NR_CPUS],
per_cpu_nice[NR_CPUS],
! per_cpu_system[NR_CPUS];
unsigned int dk_drive[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_rio[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_wio[DK_MAX_MAJOR][DK_MAX_DISK];
--- 18,25 ----
struct kernel_stat {
unsigned int per_cpu_user[NR_CPUS],
per_cpu_nice[NR_CPUS],
! per_cpu_system[NR_CPUS],
! per_cpu_iowait[NR_CPUS];
unsigned int dk_drive[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_rio[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_wio[DK_MAX_MAJOR][DK_MAX_DISK];
*** ./include/linux/swap.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/swap.h Tue May 14 16:49:58 2002
***************
*** 90,95 ****
--- 90,96 ----
extern int nr_inactive_clean_pages;
extern atomic_t page_cache_size;
extern atomic_t buffermem_pages;
+ extern atomic_t nr_iowait_tasks;
extern spinlock_cacheline_t pagecache_lock_cacheline;
#define pagecache_lock (pagecache_lock_cacheline.lock)
extern void __remove_inode_page(struct page *);
*** ./include/linux/smp_lock.h Thu Nov 22 14:46:27 2001
--- ../linux-2.4.19-pre8-ac3p/./include/linux/smp_lock.h Tue May 14 18:09:08 2002
***************
*** 3,9 ****

#include <linux/config.h>

! #ifndef CONFIG_SMP

#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
--- 3,9 ----

#include <linux/config.h>

! #if !defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT)

#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
*** ./include/linux/dcache.h Tue May 14 14:55:57 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/dcache.h Tue May 14 15:20:25 2002
***************
*** 126,156 ****

extern spinlock_t dcache_lock;

- /**
- * d_drop - drop a dentry
- * @dentry: dentry to drop
- *
- * d_drop() unhashes the entry from the parent
- * dentry hashes, so that it won't be found through
- * a VFS lookup any more. Note that this is different
- * from deleting the dentry - d_delete will try to
- * mark the dentry negative if possible, giving a
- * successful _negative_ lookup, while d_drop will
- * just make the cache lookup fail.
- *
- * d_drop() is used mainly for stuff that wants
- * to invalidate a dentry for some reason (NFS
- * timeouts or autofs deletes).
- */
-
- static __inline__ void d_drop(struct dentry * dentry)
- {
- spin_lock(&dcache_lock);
- list_del(&dentry->d_hash);
- INIT_LIST_HEAD(&dentry->d_hash);
- spin_unlock(&dcache_lock);
- }
-
static __inline__ int dname_external(struct dentry *d)
{
return d->d_name.name != d->d_iname;
--- 126,131 ----
***************
*** 275,277 ****
--- 250,283 ----
#endif /* __KERNEL__ */

#endif /* __LINUX_DCACHE_H */
+
+ #if !defined(__LINUX_DCACHE_H_INLINES) && defined(_TASK_STRUCT_DEFINED)
+ #define __LINUX_DCACHE_H_INLINES
+
+ #ifdef __KERNEL__
+ /**
+ * d_drop - drop a dentry
+ * @dentry: dentry to drop
+ *
+ * d_drop() unhashes the entry from the parent
+ * dentry hashes, so that it won't be found through
+ * a VFS lookup any more. Note that this is different
+ * from deleting the dentry - d_delete will try to
+ * mark the dentry negative if possible, giving a
+ * successful _negative_ lookup, while d_drop will
+ * just make the cache lookup fail.
+ *
+ * d_drop() is used mainly for stuff that wants
+ * to invalidate a dentry for some reason (NFS
+ * timeouts or autofs deletes).
+ */
+
+ static __inline__ void d_drop(struct dentry * dentry)
+ {
+ spin_lock(&dcache_lock);
+ list_del(&dentry->d_hash);
+ INIT_LIST_HEAD(&dentry->d_hash);
+ spin_unlock(&dcache_lock);
+ }
+ #endif
+ #endif
*** ./include/linux/smp.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/smp.h Tue May 14 15:20:25 2002
***************
*** 81,87 ****
--- 81,89 ----
#define smp_processor_id() 0
#define hard_smp_processor_id() 0
#define smp_threads_ready 1
+ #ifndef CONFIG_PREEMPT
#define kernel_lock()
+ #endif
#define cpu_logical_map(cpu) 0
#define cpu_number_map(cpu) 0
#define smp_call_function(func,info,retry,wait) ({ 0; })
*** ./include/linux/spinlock.h Tue May 14 14:55:58 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/spinlock.h Tue May 14 15:20:25 2002
***************
*** 2,7 ****
--- 2,8 ----
#define __LINUX_SPINLOCK_H

#include <linux/config.h>
+ #include <linux/compiler.h>

/*
* These are the generic versions of the spinlocks and read-write
***************
*** 62,69 ****
--- 63,72 ----

#if (DEBUG_SPINLOCKS < 1)

+ #ifndef CONFIG_PREEMPT
#define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
#define ATOMIC_DEC_AND_LOCK
+ #endif

/*
* Your basic spinlocks, allowing only a single CPU anywhere
***************
*** 79,89 ****
#endif

#define spin_lock_init(lock) do { } while(0)
! #define spin_lock(lock) (void)(lock) /* Not "unused variable". */
#define spin_is_locked(lock) (0)
! #define spin_trylock(lock) ({1; })
#define spin_unlock_wait(lock) do { } while(0)
! #define spin_unlock(lock) do { } while(0)

#elif (DEBUG_SPINLOCKS < 2)

--- 82,92 ----
#endif

#define spin_lock_init(lock) do { } while(0)
! #define _raw_spin_lock(lock) (void)(lock) /* Not "unused variable". */
#define spin_is_locked(lock) (0)
! #define _raw_spin_trylock(lock) ({1; })
#define spin_unlock_wait(lock) do { } while(0)
! #define _raw_spin_unlock(lock) do { } while(0)

#elif (DEBUG_SPINLOCKS < 2)

***************
*** 142,153 ****
#endif

#define rwlock_init(lock) do { } while(0)
! #define read_lock(lock) (void)(lock) /* Not "unused variable". */
! #define read_unlock(lock) do { } while(0)
! #define write_lock(lock) (void)(lock) /* Not "unused variable". */
! #define write_unlock(lock) do { } while(0)

#endif /* !SMP */

/* "lock on reference count zero" */
#ifndef ATOMIC_DEC_AND_LOCK
--- 145,219 ----
#endif

#define rwlock_init(lock) do { } while(0)
! #define _raw_read_lock(lock) (void)(lock) /* Not "unused variable". */
! #define _raw_read_unlock(lock) do { } while(0)
! #define _raw_write_lock(lock) (void)(lock) /* Not "unused variable". */
! #define _raw_write_unlock(lock) do { } while(0)

#endif /* !SMP */
+
+ #ifdef CONFIG_PREEMPT
+
+ #define preempt_get_count() (current->preempt_count)
+
+ #define preempt_disable() \
+ do { \
+ ++current->preempt_count; \
+ barrier(); \
+ } while (0)
+
+ #define preempt_enable_no_resched() \
+ do { \
+ --current->preempt_count; \
+ barrier(); \
+ } while (0)
+
+ #define preempt_enable() \
+ do { \
+ --current->preempt_count; \
+ barrier(); \
+ if (unlikely(current->preempt_count < current->need_resched)) \
+ preempt_schedule(); \
+ } while (0)
+
+ #define spin_lock(lock) \
+ do { \
+ preempt_disable(); \
+ _raw_spin_lock(lock); \
+ } while(0)
+
+ #define spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
+ 1 : ({preempt_enable(); 0;});})
+ #define spin_unlock(lock) \
+ do { \
+ _raw_spin_unlock(lock); \
+ preempt_enable(); \
+ } while (0)
+
+ #define read_lock(lock) ({preempt_disable(); _raw_read_lock(lock);})
+ #define read_unlock(lock) ({_raw_read_unlock(lock); preempt_enable();})
+ #define write_lock(lock) ({preempt_disable(); _raw_write_lock(lock);})
+ #define write_unlock(lock) ({_raw_write_unlock(lock); preempt_enable();})
+ #define write_trylock(lock) ({preempt_disable();_raw_write_trylock(lock) ? \
+ 1 : ({preempt_enable(); 0;});})
+
+ #else
+
+ #define preempt_get_count() (0)
+ #define preempt_disable() do { } while (0)
+ #define preempt_enable_no_resched() do {} while(0)
+ #define preempt_enable() do { } while (0)
+
+ #define spin_lock(lock) _raw_spin_lock(lock)
+ #define spin_trylock(lock) _raw_spin_trylock(lock)
+ #define spin_unlock(lock) _raw_spin_unlock(lock)
+
+ #define read_lock(lock) _raw_read_lock(lock)
+ #define read_unlock(lock) _raw_read_unlock(lock)
+ #define write_lock(lock) _raw_write_lock(lock)
+ #define write_unlock(lock) _raw_write_unlock(lock)
+ #define write_trylock(lock) _raw_write_trylock(lock)
+ #endif

/* "lock on reference count zero" */
#ifndef ATOMIC_DEC_AND_LOCK
*** ./include/linux/fs_struct.h Fri Jul 13 18:10:44 2001
--- ../linux-2.4.19-pre8-ac3p/./include/linux/fs_struct.h Tue May 14 15:09:18 2002
***************
*** 20,25 ****
--- 20,34 ----
extern void exit_fs(struct task_struct *);
extern void set_fs_altroot(void);

+ struct fs_struct *copy_fs_struct(struct fs_struct *old);
+ void put_fs_struct(struct fs_struct *fs);
+
+ #endif
+ #endif
+
+ #if !defined(_LINUX_FS_STRUCT_H_INLINES) && defined(_TASK_STRUCT_DEFINED)
+ #define _LINUX_FS_STRUCT_H_INLINES
+ #ifdef __KERNEL__
/*
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
* It can block. Requires the big lock held.
***************
*** 65,73 ****
mntput(old_pwdmnt);
}
}
-
- struct fs_struct *copy_fs_struct(struct fs_struct *old);
- void put_fs_struct(struct fs_struct *fs);
-
#endif
#endif
--- 74,78 ----
*** ./include/linux/brlock.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/linux/brlock.h Tue May 14 15:20:27 2002
***************
*** 173,183 ****
}

#else
! # define br_read_lock(idx) ((void)(idx))
! # define br_read_unlock(idx) ((void)(idx))
! # define br_write_lock(idx) ((void)(idx))
! # define br_write_unlock(idx) ((void)(idx))
! #endif

/*
* Now enumerate all of the possible sw/hw IRQ protected
--- 173,183 ----
}

#else
! # define br_read_lock(idx) ({ (void)(idx); preempt_disable(); })
! # define br_read_unlock(idx) ({ (void)(idx); preempt_enable(); })
! # define br_write_lock(idx) ({ (void)(idx); preempt_disable(); })
! # define br_write_unlock(idx) ({ (void)(idx); preempt_enable(); })
! #endif /* CONFIG_SMP */

/*
* Now enumerate all of the possible sw/hw IRQ protected
*** ./include/asm-i386/hardirq.h Thu Nov 22 14:46:19 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/hardirq.h Tue May 14 15:20:25 2002
***************
*** 36,41 ****
--- 36,43 ----

#define synchronize_irq() barrier()

+ #define release_irqlock(cpu) do { } while (0)
+
#else

#include <asm/atomic.h>
*** ./include/asm-i386/softirq.h Tue May 14 14:55:55 2002
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/softirq.h Tue May 14 15:20:25 2002
***************
*** 5,13 ****
#include <asm/hardirq.h>

#define __cpu_bh_enable(cpu) \
! do { barrier(); local_bh_count(cpu)--; } while (0)
#define cpu_bh_disable(cpu) \
! do { local_bh_count(cpu)++; barrier(); } while (0)

#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())
--- 5,13 ----
#include <asm/hardirq.h>

#define __cpu_bh_enable(cpu) \
! do { barrier(); local_bh_count(cpu)--; preempt_enable(); } while (0)
#define cpu_bh_disable(cpu) \
! do { preempt_disable(); local_bh_count(cpu)++; barrier(); } while (0)

#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())
***************
*** 22,28 ****
* If you change the offsets in irq_stat then you have to
* update this code as well.
*/
! #define local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
\
--- 22,28 ----
* If you change the offsets in irq_stat then you have to
* update this code as well.
*/
! #define _local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
\
***************
*** 44,48 ****
--- 44,50 ----
: "r" (ptr), "i" (do_softirq) \
/* no registers clobbered */ ); \
} while (0)
+
+ #define local_bh_enable() do { _local_bh_enable(); preempt_enable(); } while (0)

#endif /* __ASM_SOFTIRQ_H */
*** ./include/asm-i386/spinlock.h Tue May 14 14:55:55 2002
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/spinlock.h Tue May 14 15:20:25 2002
***************
*** 77,83 ****
:"=m" (lock->lock) : : "memory"


! static inline void spin_unlock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
if (lock->magic != SPINLOCK_MAGIC)
--- 77,83 ----
:"=m" (lock->lock) : : "memory"


! static inline void _raw_spin_unlock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
if (lock->magic != SPINLOCK_MAGIC)
***************
*** 97,103 ****
:"=q" (oldval), "=m" (lock->lock) \
:"0" (oldval) : "memory"

! static inline void spin_unlock(spinlock_t *lock)
{
char oldval = 1;
#if SPINLOCK_DEBUG
--- 97,103 ----
:"=q" (oldval), "=m" (lock->lock) \
:"0" (oldval) : "memory"

! static inline void _raw_spin_unlock(spinlock_t *lock)
{
char oldval = 1;
#if SPINLOCK_DEBUG
***************
*** 113,119 ****

#endif

! static inline int spin_trylock(spinlock_t *lock)
{
char oldval;
__asm__ __volatile__(
--- 113,119 ----

#endif

! static inline int _raw_spin_trylock(spinlock_t *lock)
{
char oldval;
__asm__ __volatile__(
***************
*** 123,129 ****
return oldval > 0;
}

! static inline void spin_lock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
__label__ here;
--- 123,129 ----
return oldval > 0;
}

! static inline void _raw_spin_lock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
__label__ here;
***************
*** 179,185 ****
*/
/* the spinlock helpers are in arch/i386/kernel/semaphore.c */

! static inline void read_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
--- 179,185 ----
*/
/* the spinlock helpers are in arch/i386/kernel/semaphore.c */

! static inline void _raw_read_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
***************
*** 188,194 ****
__build_read_lock(rw, "__read_lock_failed");
}

! static inline void write_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
--- 188,194 ----
__build_read_lock(rw, "__read_lock_failed");
}

! static inline void _raw_write_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
***************
*** 197,206 ****
__build_write_lock(rw, "__write_lock_failed");
}

! #define read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
! #define write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")

! static inline int write_trylock(rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;
if (atomic_sub_and_test(RW_LOCK_BIAS, count))
--- 197,206 ----
__build_write_lock(rw, "__write_lock_failed");
}

! #define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
! #define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")

! static inline int _raw_write_trylock(rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;
if (atomic_sub_and_test(RW_LOCK_BIAS, count))
*** ./include/asm-i386/smplock.h Tue May 14 14:55:55 2002
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/smplock.h Tue May 14 18:09:08 2002
***************
*** 11,17 ****
--- 11,25 ----
extern spinlock_cacheline_t kernel_flag_cacheline;
#define kernel_flag kernel_flag_cacheline.lock

+ #ifdef CONFIG_SMP
#define kernel_locked() spin_is_locked(&kernel_flag)
+ #else
+ #ifdef CONFIG_PREEMPT
+ #define kernel_locked() preempt_get_count()
+ #else
+ #define kernel_locked() 1
+ #endif
+ #endif

/*
* Release global kernel lock and global interrupt lock
***************
*** 43,48 ****
--- 51,61 ----
*/
static __inline__ void lock_kernel(void)
{
+ #ifdef CONFIG_PREEMPT
+ if (current->lock_depth == -1)
+ spin_lock(&kernel_flag);
+ ++current->lock_depth;
+ #else
#if 1
if (!++current->lock_depth)
spin_lock(&kernel_flag);
***************
*** 54,59 ****
--- 67,73 ----
"\n9:"
:"=m" (__dummy_lock(&kernel_flag)),
"=m" (current->lock_depth));
+ #endif
#endif
}

*** ./include/asm-i386/hw_irq.h Thu Nov 22 14:46:18 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/hw_irq.h Tue May 14 15:20:25 2002
***************
*** 95,100 ****
--- 95,112 ----
#define __STR(x) #x
#define STR(x) __STR(x)

+ #define GET_CURRENT \
+ "movl %esp, %ebx\n\t" \
+ "andl $-8192, %ebx\n\t"
+
+ #ifdef CONFIG_PREEMPT
+ #define BUMP_LOCK_COUNT \
+ GET_CURRENT \
+ "incl 4(%ebx)\n\t"
+ #else
+ #define BUMP_LOCK_COUNT
+ #endif
+
#define SAVE_ALL \
"cld\n\t" \
"pushl %es\n\t" \
***************
*** 108,121 ****
"pushl %ebx\n\t" \
"movl $" STR(__KERNEL_DS) ",%edx\n\t" \
"movl %edx,%ds\n\t" \
! "movl %edx,%es\n\t"

#define IRQ_NAME2(nr) nr##_interrupt(void)
#define IRQ_NAME(nr) IRQ_NAME2(IRQ##nr)
-
- #define GET_CURRENT \
- "movl %esp, %ebx\n\t" \
- "andl $-8192, %ebx\n\t"

/*
* SMP has a few special interrupts for IPI messages
--- 120,130 ----
"pushl %ebx\n\t" \
"movl $" STR(__KERNEL_DS) ",%edx\n\t" \
"movl %edx,%ds\n\t" \
! "movl %edx,%es\n\t" \
! BUMP_LOCK_COUNT

#define IRQ_NAME2(nr) nr##_interrupt(void)
#define IRQ_NAME(nr) IRQ_NAME2(IRQ##nr)

/*
* SMP has a few special interrupts for IPI messages
*** ./include/asm-i386/highmem.h Tue May 14 14:55:55 2002
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/highmem.h Tue May 14 15:20:25 2002
***************
*** 88,93 ****
--- 88,94 ----
enum fixed_addresses idx;
unsigned long vaddr;

+ preempt_disable();
if (page < highmem_start_page)
return page_address(page);

***************
*** 109,116 ****
unsigned long vaddr = (unsigned long) kvaddr;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();

! if (vaddr < FIXADDR_START) // FIXME
return;

if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
out_of_line_bug();
--- 110,119 ----
unsigned long vaddr = (unsigned long) kvaddr;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();

! if (vaddr < FIXADDR_START) { // FIXME
! preempt_enable();
return;
+ }

if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
out_of_line_bug();
***************
*** 122,127 ****
--- 125,132 ----
pte_clear(kmap_pte-idx);
__flush_tlb_one(vaddr);
#endif
+
+ preempt_enable();
}

#endif /* __KERNEL__ */
*** ./include/asm-i386/pgalloc.h Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/pgalloc.h Tue May 14 15:20:25 2002
***************
*** 75,94 ****
{
unsigned long *ret;

if ((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)(*ret);
ret[0] = 0;
pgtable_cache_size--;
! } else
ret = (unsigned long *)get_pgd_slow();
return (pgd_t *)ret;
}

static inline void free_pgd_fast(pgd_t *pgd)
{
*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
}

static inline void free_pgd_slow(pgd_t *pgd)
--- 75,100 ----
{
unsigned long *ret;

+ preempt_disable();
if ((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)(*ret);
ret[0] = 0;
pgtable_cache_size--;
! preempt_enable();
! } else {
! preempt_enable();
ret = (unsigned long *)get_pgd_slow();
+ }
return (pgd_t *)ret;
}

static inline void free_pgd_fast(pgd_t *pgd)
{
+ preempt_disable();
*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
+ preempt_enable();
}

static inline void free_pgd_slow(pgd_t *pgd)
***************
*** 119,129 ****
--- 125,137 ----
{
unsigned long *ret;

+ preempt_disable();
if ((ret = (unsigned long *)pte_quicklist) != NULL) {
pte_quicklist = (unsigned long *)(*ret);
ret[0] = ret[1];
pgtable_cache_size--;
}
+ preempt_enable();
return (pte_t *)ret;
}

***************
*** 135,146 ****
--- 143,156 ----
extern int pgt_cache_water[];
static inline void pte_free_fast(pte_t *pte)
{
+ preempt_disable();
if (pgtable_cache_size < pgt_cache_water[1]) {
*(unsigned long *)pte = (unsigned long) pte_quicklist;
pte_quicklist = (unsigned long *) pte;
pgtable_cache_size++;
} else
pte_free_slow(pte);
+ preempt_enable();
}

#define pte_free(pte) pte_free_fast(pte)
*** ./include/asm-i386/i387.h Thu Nov 22 14:48:58 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-i386/i387.h Tue May 14 18:09:08 2002
***************
*** 12,17 ****
--- 12,18 ----
#define __ASM_I386_I387_H

#include <linux/sched.h>
+ #include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>
#include <asm/user.h>
***************
*** 24,30 ****
extern void restore_fpu( struct task_struct *tsk );

extern void kernel_fpu_begin(void);
! #define kernel_fpu_end() stts()


#define unlazy_fpu( tsk ) do { \
--- 25,31 ----
extern void restore_fpu( struct task_struct *tsk );

extern void kernel_fpu_begin(void);
! #define kernel_fpu_end() do { stts(); preempt_enable(); } while(0)


#define unlazy_fpu( tsk ) do { \
*** ./include/asm-arm/dma.h Sun Aug 12 14:14:00 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-arm/dma.h Tue May 14 15:09:18 2002
***************
*** 5,10 ****
--- 5,11 ----

#include <linux/config.h>
#include <linux/spinlock.h>
+ #include <linux/sched.h>
#include <asm/system.h>
#include <asm/memory.h>
#include <asm/scatterlist.h>
*** ./include/asm-arm/hardirq.h Thu Oct 11 12:04:57 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-arm/hardirq.h Tue May 14 15:09:18 2002
***************
*** 34,39 ****
--- 34,40 ----
#define irq_exit(cpu,irq) (local_irq_count(cpu)--)

#define synchronize_irq() do { } while (0)
+ #define release_irqlock(cpu) do { } while (0)

#else
#error SMP not supported
*** ./include/asm-arm/smplock.h Sun Aug 12 14:14:00 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-arm/smplock.h Tue May 14 15:09:18 2002
***************
*** 3,14 ****
--- 3,19 ----
*
* Default SMP lock implementation
*/
+ #include <linux/config.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>

extern spinlock_t kernel_flag;

+ #ifdef CONFIG_PREEMPT
+ #define kernel_locked() preempt_get_count()
+ #else
#define kernel_locked() spin_is_locked(&kernel_flag)
+ #endif

/*
* Release global kernel lock and global interrupt lock
***************
*** 40,47 ****
--- 45,58 ----
*/
static inline void lock_kernel(void)
{
+ #ifdef CONFIG_PREEMPT
+ if (current->lock_depth == -1)
+ spin_lock(&kernel_flag);
+ ++current->lock_depth;
+ #else
if (!++current->lock_depth)
spin_lock(&kernel_flag);
+ #endif
}

static inline void unlock_kernel(void)
*** ./include/asm-arm/softirq.h Sat Sep 8 15:02:31 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-arm/softirq.h Tue May 14 15:09:18 2002
***************
*** 5,24 ****
#include <asm/hardirq.h>

#define __cpu_bh_enable(cpu) \
! do { barrier(); local_bh_count(cpu)--; } while (0)
#define cpu_bh_disable(cpu) \
! do { local_bh_count(cpu)++; barrier(); } while (0)

#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())

#define in_softirq() (local_bh_count(smp_processor_id()) != 0)

! #define local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
if (!--*ptr && ptr[-2]) \
__asm__("bl%? __do_softirq": : : "lr");/* out of line */\
} while (0)

#endif /* __ASM_SOFTIRQ_H */
--- 5,26 ----
#include <asm/hardirq.h>

#define __cpu_bh_enable(cpu) \
! do { barrier(); local_bh_count(cpu)--; preempt_enable(); } while (0)
#define cpu_bh_disable(cpu) \
! do { preempt_disable(); local_bh_count(cpu)++; barrier(); } while (0)

#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())

#define in_softirq() (local_bh_count(smp_processor_id()) != 0)

! #define _local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
if (!--*ptr && ptr[-2]) \
__asm__("bl%? __do_softirq": : : "lr");/* out of line */\
} while (0)
+
+ #define local_bh_enable() do { _local_bh_enable(); preempt_enable(); } while (0)

#endif /* __ASM_SOFTIRQ_H */
*** ./include/asm-arm/pgalloc.h Sun Aug 12 14:14:00 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-arm/pgalloc.h Tue May 14 15:09:18 2002
***************
*** 57,96 ****
--- 57,104 ----
{
unsigned long *ret;

+ preempt_disable();
if ((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)__pgd_next(ret);
ret[1] = ret[2];
clean_dcache_entry(ret + 1);
pgtable_cache_size--;
}
+ preempt_enable();
return (pgd_t *)ret;
}

static inline void free_pgd_fast(pgd_t *pgd)
{
+ preempt_disable();
__pgd_next(pgd) = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
+ preempt_enable();
}

static inline pte_t *pte_alloc_one_fast(struct mm_struct *mm, unsigned long address)
{
unsigned long *ret;

+ preempt_disable();
if((ret = pte_quicklist) != NULL) {
pte_quicklist = (unsigned long *)__pte_next(ret);
ret[0] = 0;
clean_dcache_entry(ret);
pgtable_cache_size--;
}
+ preempt_enable();
return (pte_t *)ret;
}

static inline void free_pte_fast(pte_t *pte)
{
+ preempt_disable();
__pte_next(pte) = (unsigned long) pte_quicklist;
pte_quicklist = (unsigned long *) pte;
pgtable_cache_size++;
+ preempt_enable();
}

#else /* CONFIG_NO_PGT_CACHE */
*** ./include/asm-sh/hardirq.h Sat Sep 8 15:29:09 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-sh/hardirq.h Tue May 14 15:09:18 2002
***************
*** 34,39 ****
--- 34,41 ----

#define synchronize_irq() barrier()

+ #define release_irqlock(cpu) do { } while (0)
+
#else

#error Super-H SMP is not available
*** ./include/asm-sh/smplock.h Sat Sep 8 15:29:09 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-sh/smplock.h Tue May 14 15:09:18 2002
***************
*** 9,23 ****

#include <linux/config.h>

! #ifndef CONFIG_SMP
!
#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
! #define release_kernel_lock(task, cpu, depth) ((depth) = 1)
! #define reacquire_kernel_lock(task, cpu, depth) do { } while(0)

#else
! #error "We do not support SMP on SH"
! #endif /* CONFIG_SMP */

#endif /* __ASM_SH_SMPLOCK_H */
--- 9,96 ----

#include <linux/config.h>

! #if !defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT)
! /*
! * Should never happen, since linux/smp_lock.h catches this case;
! * but in case this file is included directly with neither SMP nor
! * PREEMPT configuration, provide same dummys as linux/smp_lock.h
! */
#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
! #define release_kernel_lock(task, cpu) do { } while(0)
! #define reacquire_kernel_lock(task) do { } while(0)
! #define kernel_locked() 1
!
! #else /* CONFIG_SMP || CONFIG_PREEMPT */
!
! #if CONFIG_SMP
! #error "We do not support SMP on SH yet"
! #endif
! /*
! * Default SMP lock implementation (i.e. the i386 version)
! */
!
! #include <linux/interrupt.h>
! #include <linux/spinlock.h>
!
! extern spinlock_t kernel_flag;
! #define lock_bkl() spin_lock(&kernel_flag)
! #define unlock_bkl() spin_unlock(&kernel_flag)

+ #ifdef CONFIG_SMP
+ #define kernel_locked() spin_is_locked(&kernel_flag)
+ #elif CONFIG_PREEMPT
+ #define kernel_locked() preempt_get_count()
+ #else /* neither */
+ #define kernel_locked() 1
+ #endif
+
+ /*
+ * Release global kernel lock and global interrupt lock
+ */
+ #define release_kernel_lock(task, cpu) \
+ do { \
+ if (task->lock_depth >= 0) \
+ spin_unlock(&kernel_flag); \
+ release_irqlock(cpu); \
+ __sti(); \
+ } while (0)
+
+ /*
+ * Re-acquire the kernel lock
+ */
+ #define reacquire_kernel_lock(task) \
+ do { \
+ if (task->lock_depth >= 0) \
+ spin_lock(&kernel_flag); \
+ } while (0)
+
+ /*
+ * Getting the big kernel lock.
+ *
+ * This cannot happen asynchronously,
+ * so we only need to worry about other
+ * CPU's.
+ */
+ static __inline__ void lock_kernel(void)
+ {
+ #ifdef CONFIG_PREEMPT
+ if (current->lock_depth == -1)
+ spin_lock(&kernel_flag);
+ ++current->lock_depth;
#else
! if (!++current->lock_depth)
! spin_lock(&kernel_flag);
! #endif
! }
!
! static __inline__ void unlock_kernel(void)
! {
! if (current->lock_depth < 0)
! BUG();
! if (--current->lock_depth < 0)
! spin_unlock(&kernel_flag);
! }
! #endif /* CONFIG_SMP || CONFIG_PREEMPT */

#endif /* __ASM_SH_SMPLOCK_H */
*** ./include/asm-sh/softirq.h Sat Sep 8 15:29:09 2001
--- ../linux-2.4.19-pre8-ac3p/./include/asm-sh/softirq.h Tue May 14 15:09:18 2002
***************
*** 6,11 ****
--- 6,12 ----

#define local_bh_disable() \
do { \
+ preempt_disable(); \
local_bh_count(smp_processor_id())++; \
barrier(); \
} while (0)
***************
*** 14,19 ****
--- 15,21 ----
do { \
barrier(); \
local_bh_count(smp_processor_id())--; \
+ preempt_enable(); \
} while (0)

#define local_bh_enable() \
***************
*** 23,28 ****
--- 25,31 ----
&& softirq_pending(smp_processor_id())) { \
do_softirq(); \
} \
+ preempt_enable(); \
} while (0)

#define in_softirq() (local_bh_count(smp_processor_id()) != 0)
*** ./net/socket.c Tue May 14 14:59:20 2002
--- ../linux-2.4.19-pre8-ac3p/./net/socket.c Tue May 14 15:09:18 2002
***************
*** 132,138 ****

static struct net_proto_family *net_families[NPROTO];

! #ifdef CONFIG_SMP
static atomic_t net_family_lockct = ATOMIC_INIT(0);
static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED;

--- 132,138 ----

static struct net_proto_family *net_families[NPROTO];

! #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
static atomic_t net_family_lockct = ATOMIC_INIT(0);
static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED;

*** ./net/sunrpc/pmap_clnt.c Tue May 14 14:56:02 2002
--- ../linux-2.4.19-pre8-ac3p/./net/sunrpc/pmap_clnt.c Tue May 14 15:09:18 2002
***************
*** 12,17 ****
--- 12,18 ----
#include <linux/config.h>
#include <linux/types.h>
#include <linux/socket.h>
+ #include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/uio.h>
*** ./MAINTAINERS Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./MAINTAINERS Tue May 14 15:09:17 2002
***************
*** 1317,1322 ****
--- 1317,1330 ----
M: mostrows@styx.uwaterloo.ca
S: Maintained

+ PREEMPTIBLE KERNEL
+ P: Robert M. Love
+ M: rml@tech9.net
+ L: linux-kernel@vger.kernel.org
+ L: kpreempt-tech@lists.sourceforge.net
+ W: http://tech9.net/rml/linux
+ S: Supported
+
PROMISE DC4030 CACHING DISK CONTROLLER DRIVER
P: Peter Denison
M: promise@pnd-pc.demon.co.uk
*** ./drivers/sound/sound_core.c Sun Sep 30 15:26:08 2001
--- ../linux-2.4.19-pre8-ac3p/./drivers/sound/sound_core.c Tue May 14 15:09:17 2002
***************
*** 37,42 ****
--- 37,43 ----
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
+ #include <linux/sched.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
*** ./drivers/ieee1394/csr.c Tue May 14 14:55:42 2002
--- ../linux-2.4.19-pre8-ac3p/./drivers/ieee1394/csr.c Tue May 14 15:09:17 2002
***************
*** 10,15 ****
--- 10,16 ----
*/

#include <linux/string.h>
+ #include <linux/sched.h>

#include "ieee1394_types.h"
#include "hosts.h"
*** ./arch/i386/config.in Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/i386/config.in Tue May 14 15:09:17 2002
***************
*** 199,204 ****
--- 199,205 ----
bool 'Math emulation' CONFIG_MATH_EMULATION
bool 'MTRR (Memory Type Range Register) support' CONFIG_MTRR
bool 'Symmetric multi-processing support' CONFIG_SMP
+ bool 'Preemptible Kernel' CONFIG_PREEMPT
if [ "$CONFIG_SMP" != "y" ]; then
bool 'Local APIC support on uniprocessors' CONFIG_X86_UP_APIC
dep_bool 'IO-APIC support on uniprocessors' CONFIG_X86_UP_IOAPIC $CONFIG_X86_UP_APIC
***************
*** 212,220 ****
bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
fi

! if [ "$CONFIG_SMP" = "y" -a "$CONFIG_X86_CMPXCHG" = "y" ]; then
! define_bool CONFIG_HAVE_DEC_LOCK y
fi
endmenu

mainmenu_option next_comment
--- 213,224 ----
bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
fi

! if [ "$CONFIG_SMP" = "y" -o "$CONFIG_PREEMPT" = "y" ]; then
! if [ "$CONFIG_X86_CMPXCHG" = "y" ]; then
! define_bool CONFIG_HAVE_DEC_LOCK y
! fi
fi
+
endmenu

mainmenu_option next_comment
*** ./arch/i386/lib/dec_and_lock.c Fri Jul 7 21:20:16 2000
--- ../linux-2.4.19-pre8-ac3p/./arch/i386/lib/dec_and_lock.c Tue May 14 15:09:17 2002
***************
*** 8,13 ****
--- 8,14 ----
*/

#include <linux/spinlock.h>
+ #include <linux/sched.h>
#include <asm/atomic.h>

int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
*** ./arch/i386/kernel/entry.S Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/i386/kernel/entry.S Tue May 14 15:09:17 2002
***************
*** 71,77 ****
* these are offsets into the task-struct.
*/
state = 0
! flags = 4
sigpending = 8
addr_limit = 12
exec_domain = 16
--- 71,77 ----
* these are offsets into the task-struct.
*/
state = 0
! preempt_count = 4
sigpending = 8
addr_limit = 12
exec_domain = 16
***************
*** 79,86 ****
--- 79,106 ----
tsk_ptrace = 24
cpu = 32

+ /* These are offsets into the irq_stat structure
+ * There is one per cpu and it is aligned to 32
+ * byte boundry (we put that here as a shift count)
+ */
+ irq_array_shift = CONFIG_X86_L1_CACHE_SHIFT
+
+ irq_stat_local_irq_count = 4
+ irq_stat_local_bh_count = 8
+
ENOSYS = 38

+ #ifdef CONFIG_SMP
+ #define GET_CPU_INDX movl cpu(%ebx),%eax; \
+ shll $irq_array_shift,%eax
+ #define GET_CURRENT_CPU_INDX GET_CURRENT(%ebx); \
+ GET_CPU_INDX
+ #define CPU_INDX (,%eax)
+ #else
+ #define GET_CPU_INDX
+ #define GET_CURRENT_CPU_INDX GET_CURRENT(%ebx)
+ #define CPU_INDX
+ #endif

#define SAVE_ALL \
cld; \
***************
*** 176,182 ****


ENTRY(ret_from_fork)
! #if CONFIG_SMP
pushl %ebx
call SYMBOL_NAME(schedule_tail)
addl $4, %esp
--- 196,202 ----


ENTRY(ret_from_fork)
! #if CONFIG_SMP || CONFIG_PREEMPT
pushl %ebx
call SYMBOL_NAME(schedule_tail)
addl $4, %esp
***************
*** 249,260 ****
--- 269,298 ----
ALIGN
ENTRY(ret_from_intr)
GET_CURRENT(%ebx)
+ #ifdef CONFIG_PREEMPT
+ cli
+ decl preempt_count(%ebx)
+ #endif
ret_from_exception:
movl EFLAGS(%esp),%eax # mix EFLAGS and CS
movb CS(%esp),%al
testl $(VM_MASK | 3),%eax # return to VM86 mode or non-supervisor?
jne ret_from_sys_call
+ #ifdef CONFIG_PREEMPT
+ cmpl $0,preempt_count(%ebx)
+ jnz restore_all
+ cmpl $0,need_resched(%ebx)
+ jz restore_all
+ movl SYMBOL_NAME(irq_stat)+irq_stat_local_bh_count CPU_INDX,%ecx
+ addl SYMBOL_NAME(irq_stat)+irq_stat_local_irq_count CPU_INDX,%ecx
+ jnz restore_all
+ incl preempt_count(%ebx)
+ sti
+ call SYMBOL_NAME(preempt_schedule)
+ jmp ret_from_intr
+ #else
jmp restore_all
+ #endif

ALIGN
reschedule:
***************
*** 291,296 ****
--- 329,337 ----
GET_CURRENT(%ebx)
call *%edi
addl $8,%esp
+ #ifdef CONFIG_PREEMPT
+ cli
+ #endif
jmp ret_from_exception

ENTRY(coprocessor_error)
***************
*** 310,321 ****
--- 351,368 ----
movl %cr0,%eax
testl $0x4,%eax # EM (math emulation bit)
jne device_not_available_emulate
+ #ifdef CONFIG_PREEMPT
+ cli
+ #endif
call SYMBOL_NAME(math_state_restore)
jmp ret_from_exception
device_not_available_emulate:
pushl $0 # temporary storage for ORIG_EIP
call SYMBOL_NAME(math_emulate)
addl $4,%esp
+ #ifdef CONFIG_PREEMPT
+ cli
+ #endif
jmp ret_from_exception

ENTRY(debug)
*** ./arch/i386/kernel/traps.c Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/i386/kernel/traps.c Tue May 14 15:09:17 2002
***************
*** 756,761 ****
--- 756,763 ----
*
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
+ *
+ * Must be called with kernel preemption disabled.
*/
asmlinkage void math_state_restore(struct pt_regs regs)
{
*** ./arch/i386/kernel/i387.c Fri Feb 23 13:09:08 2001
--- ../linux-2.4.19-pre8-ac3p/./arch/i386/kernel/i387.c Tue May 14 15:09:17 2002
***************
*** 10,15 ****
--- 10,16 ----

#include <linux/config.h>
#include <linux/sched.h>
+ #include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/math_emu.h>
***************
*** 65,70 ****
--- 66,73 ----
{
struct task_struct *tsk = current;

+ preempt_disable();
+
if (tsk->flags & PF_USEDFPU) {
__save_init_fpu(tsk);
return;
*** ./arch/arm/config.in Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/arm/config.in Tue May 14 15:09:17 2002
***************
*** 552,557 ****
--- 552,558 ----
if [ "$CONFIG_ISDN" != "n" ]; then
source drivers/isdn/Config.in
fi
+ dep_bool 'Preemptible Kernel' CONFIG_PREEMPT $CONFIG_CPU_32
endmenu

#
*** ./arch/arm/kernel/entry-armv.S Tue May 14 14:55:40 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/arm/kernel/entry-armv.S Tue May 14 15:09:17 2002
***************
*** 697,702 ****
--- 697,708 ----
add r4, sp, #S_SP
mov r6, lr
stmia r4, {r5, r6, r7, r8, r9} @ save sp_SVC, lr_SVC, pc, cpsr, old_ro
+ #ifdef CONFIG_PREEMPT
+ get_current_task r9
+ ldr r8, [r9, #TSK_PREEMPT]
+ add r8, r8, #1
+ str r8, [r9, #TSK_PREEMPT]
+ #endif
1: get_irqnr_and_base r0, r6, r5, lr
movne r1, sp
@
***************
*** 704,709 ****
--- 710,734 ----
@
adrsvc ne, lr, 1b
bne do_IRQ
+ #ifdef CONFIG_PREEMPT
+ 2: ldr r8, [r9, #TSK_PREEMPT]
+ subs r8, r8, #1
+ bne 3f
+ ldr r7, [r9, #TSK_NEED_RESCHED]
+ teq r7, #0
+ beq 3f
+ ldr r6, .LCirqstat
+ ldr r0, [r6, #IRQSTAT_BH_COUNT]
+ teq r0, #0
+ bne 3f
+ mov r0, #MODE_SVC
+ msr cpsr_c, r0 @ enable interrupts
+ bl SYMBOL_NAME(preempt_schedule)
+ mov r0, #I_BIT | MODE_SVC
+ msr cpsr_c, r0 @ disable interrupts
+ b 2b
+ 3: str r8, [r9, #TSK_PREEMPT]
+ #endif
ldr r0, [sp, #S_PSR] @ irqs are already disabled
msr spsr, r0
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
***************
*** 761,766 ****
--- 786,794 ----
.LCprocfns: .word SYMBOL_NAME(processor)
#endif
.LCfp: .word SYMBOL_NAME(fp_enter)
+ #ifdef CONFIG_PREEMPT
+ .LCirqstat: .word SYMBOL_NAME(irq_stat)
+ #endif

irq_prio_table

***************
*** 801,806 ****
--- 829,840 ----
stmdb r8, {sp, lr}^
alignment_trap r4, r7, __temp_irq
zero_fp
+ get_current_task tsk
+ #ifdef CONFIG_PREEMPT
+ ldr r0, [tsk, #TSK_PREEMPT]
+ add r0, r0, #1
+ str r0, [tsk, #TSK_PREEMPT]
+ #endif
1: get_irqnr_and_base r0, r6, r5, lr
movne r1, sp
adrsvc ne, lr, 1b
***************
*** 808,815 ****
@ routine called with r0 = irq number, r1 = struct pt_regs *
@
bne do_IRQ
mov why, #0
- get_current_task tsk
b ret_to_user

.align 5
--- 842,853 ----
@ routine called with r0 = irq number, r1 = struct pt_regs *
@
bne do_IRQ
+ #ifdef CONFIG_PREEMPT
+ ldr r0, [tsk, #TSK_PREEMPT]
+ sub r0, r0, #1
+ str r0, [tsk, #TSK_PREEMPT]
+ #endif
mov why, #0
b ret_to_user

.align 5
*** ./arch/arm/tools/getconstants.c Thu Oct 11 12:04:57 2001
--- ../linux-2.4.19-pre8-ac3p/./arch/arm/tools/getconstants.c Tue May 14 15:09:17 2002
***************
*** 13,18 ****
--- 13,19 ----

#include <asm/pgtable.h>
#include <asm/uaccess.h>
+ #include <asm/hardirq.h>

/*
* Make sure that the compiler and target are compatible.
***************
*** 38,43 ****
--- 39,49 ----

DEFN("TSS_SAVE", OFF_TSK(thread.save));
DEFN("TSS_FPESAVE", OFF_TSK(thread.fpstate.soft.save));
+
+ #ifdef CONFIG_PREEMPT
+ DEFN("TSK_PREEMPT", OFF_TSK(preempt_count));
+ DEFN("IRQSTAT_BH_COUNT", (unsigned long)&(((irq_cpustat_t *)0)->__local_bh_count));
+ #endif

#ifdef CONFIG_CPU_32
DEFN("TSS_DOMAIN", OFF_TSK(thread.domain));
*** ./arch/sh/config.in Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/sh/config.in Tue May 14 15:09:17 2002
***************
*** 124,129 ****
--- 124,130 ----
hex 'Physical memory start address' CONFIG_MEMORY_START 08000000
hex 'Physical memory size' CONFIG_MEMORY_SIZE 00400000
fi
+ bool 'Preemptible Kernel' CONFIG_PREEMPT
endmenu

if [ "$CONFIG_SH_HP690" = "y" ]; then
*** ./arch/sh/kernel/entry.S Tue May 14 14:55:42 2002
--- ../linux-2.4.19-pre8-ac3p/./arch/sh/kernel/entry.S Tue May 14 15:09:17 2002
***************
*** 60,69 ****
/*
* These are offsets into the task-struct.
*/
! flags = 4
sigpending = 8
need_resched = 20
tsk_ptrace = 24

PT_TRACESYS = 0x00000002
PF_USEDFPU = 0x00100000
--- 60,77 ----
/*
* These are offsets into the task-struct.
*/
! preempt_count = 4
sigpending = 8
need_resched = 20
tsk_ptrace = 24
+ flags = 84
+
+ /*
+ * These offsets are into irq_stat.
+ * (Find irq_cpustat_t in asm-sh/hardirq.h)
+ */
+ local_irq_count = 8
+ local_bh_count = 12

PT_TRACESYS = 0x00000002
PF_USEDFPU = 0x00100000
***************
*** 143,149 ****
mov.l __INV_IMASK, r11; \
stc sr, r10; \
and r11, r10; \
! stc k_g_imask, r11; \
or r11, r10; \
ldc r10, sr

--- 151,157 ----
mov.l __INV_IMASK, r11; \
stc sr, r10; \
and r11, r10; \
! stc k_g_imask, r11; \
or r11, r10; \
ldc r10, sr

***************
*** 304,311 ****
mov.l @(tsk_ptrace,r0), r0 ! Is current PTRACE_SYSCALL'd?
mov #PT_TRACESYS, r1
tst r1, r0
! bt ret_from_syscall
! bra syscall_ret_trace
nop

.align 2
--- 312,319 ----
mov.l @(tsk_ptrace,r0), r0 ! Is current PTRACE_SYSCALL'd?
mov #PT_TRACESYS, r1
tst r1, r0
! bf syscall_ret_trace
! bra ret_from_syscall
nop

.align 2
***************
*** 505,512 ****
.long syscall_ret_trace
__syscall_ret:
.long syscall_ret
- __INV_IMASK:
- .long 0xffffff0f ! ~(IMASK)


.align 2
--- 513,518 ----
***************
*** 518,524 ****
--- 524,607 ----
.align 2
1: .long SYMBOL_NAME(schedule)

+ #ifdef CONFIG_PREEMPT
+ !
+ ! Returning from interrupt during kernel mode: check if
+ ! preempt_schedule should be called. If need_resched flag
+ ! is set, preempt_count is zero, and we're not currently
+ ! in an interrupt handler (local irq or bottom half) then
+ ! call preempt_schedule.
+ !
+ ! Increment preempt_count to prevent a nested interrupt
+ ! from reentering preempt_schedule, then decrement after
+ ! and drop through to regular interrupt return which will
+ ! jump back and check again in case such an interrupt did
+ ! come in (and didn't preempt due to preempt_count).
+ !
+ ! NOTE: because we just checked that preempt_count was
+ ! zero before getting to the call, can't we use immediate
+ ! values (1 and 0) rather than inc/dec? Also, rather than
+ ! drop through to ret_from_irq, we already know this thread
+ ! is kernel mode, can't we go direct to ret_from_kirq? In
+ ! fact, with proper interrupt nesting and so forth could
+ ! the loop simply be on the need_resched w/o checking the
+ ! other stuff again? Optimize later...
+ !
+ .align 2
+ ret_from_kirq:
+ ! Nonzero preempt_count prevents scheduling
+ stc k_current, r1
+ mov.l @(preempt_count,r1), r0
+ cmp/eq #0, r0
+ bf restore_all
+ ! Zero need_resched prevents scheduling
+ mov.l @(need_resched,r1), r0
+ cmp/eq #0, r0
+ bt restore_all
+ ! If in_interrupt(), don't schedule
+ mov.l __irq_stat, r1
+ mov.l @(local_irq_count,r1), r0
+ mov.l @(local_bh_count,r1), r1
+ or r1, r0
+ cmp/eq #0, r0
+ bf restore_all
+ ! Allow scheduling using preempt_schedule
+ ! Adjust preempt_count and SR as needed.
+ stc k_current, r1
+ mov.l @(preempt_count,r1), r0 ! Could replace this ...
+ add #1, r0 ! ... and this w/mov #1?
+ mov.l r0, @(preempt_count,r1)
+ STI()
+ mov.l __preempt_schedule, r0
+ jsr @r0
+ nop
+ /* CLI */
+ stc sr, r0
+ or #0xf0, r0
+ ldc r0, sr
+ !
+ stc k_current, r1
+ mov.l @(preempt_count,r1), r0 ! Could replace this ...
+ add #-1, r0 ! ... and this w/mov #0?
+ mov.l r0, @(preempt_count,r1)
+ ! Maybe should bra ret_from_kirq, or loop over need_resched?
+ ! For now, fall through to ret_from_irq again...
+ #endif /* CONFIG_PREEMPT */
+
ret_from_irq:
+ mov #OFF_SR, r0
+ mov.l @(r0,r15), r0 ! get status register
+ shll r0
+ shll r0 ! kernel space?
+ #ifndef CONFIG_PREEMPT
+ bt restore_all ! Yes, it's from kernel, go back soon
+ #else /* CONFIG_PREEMPT */
+ bt ret_from_kirq ! From kernel: maybe preempt_schedule
+ #endif /* CONFIG_PREEMPT */
+ !
+ bra ret_from_syscall
+ nop
+
ret_from_exception:
mov #OFF_SR, r0
mov.l @(r0,r15), r0 ! get status register
***************
*** 564,569 ****
--- 647,659 ----
.long SYMBOL_NAME(do_signal)
__irq_stat:
.long SYMBOL_NAME(irq_stat)
+ #ifdef CONFIG_PREEMPT
+ __preempt_schedule:
+ .long SYMBOL_NAME(preempt_schedule)
+ #endif /* CONFIG_PREEMPT */
+ __INV_IMASK:
+ .long 0xffffff0f ! ~(IMASK)
+

.align 2
restore_all:
***************
*** 679,685 ****
__fpu_prepare_fd:
.long SYMBOL_NAME(fpu_prepare_fd)
__init_task_flags:
! .long SYMBOL_NAME(init_task_union)+4
__PF_USEDFPU:
.long PF_USEDFPU
#endif
--- 769,775 ----
__fpu_prepare_fd:
.long SYMBOL_NAME(fpu_prepare_fd)
__init_task_flags:
! .long SYMBOL_NAME(init_task_union)+flags
__PF_USEDFPU:
.long PF_USEDFPU
#endif
*** ./arch/sh/kernel/irq.c Sat Sep 8 15:29:09 2001
--- ../linux-2.4.19-pre8-ac3p/./arch/sh/kernel/irq.c Tue May 14 15:09:17 2002
***************
*** 229,234 ****
--- 229,242 ----
struct irqaction * action;
unsigned int status;

+ /*
+ * At this point we're now about to actually call handlers,
+ * and interrupts might get reenabled during them... bump
+ * preempt_count to prevent any preemption while the handler
+ * called here is pending...
+ */
+ preempt_disable();
+
/* Get IRQ number */
asm volatile("stc r2_bank, %0\n\t"
"shlr2 %0\n\t"
***************
*** 298,305 ****
--- 306,322 ----
desc->handler->end(irq);
spin_unlock(&desc->lock);

+
if (softirq_pending(cpu))
do_softirq();
+
+ /*
+ * We're done with the handlers, interrupts should be
+ * currently disabled; decrement preempt_count now so
+ * as we return preemption may be allowed...
+ */
+ preempt_enable_no_resched();
+
return 1;
}

*** ./Documentation/Configure.help Tue May 14 14:59:18 2002
--- ../linux-2.4.19-pre8-ac3p/./Documentation/Configure.help Tue May 14 15:09:17 2002
***************
*** 291,296 ****
--- 291,307 ----
If you have a system with several CPUs, you do not need to say Y
here: the local APIC will be used automatically.

+ Preemptible Kernel
+ CONFIG_PREEMPT
+ This option reduces the latency of the kernel when reacting to
+ real-time or interactive events by allowing a low priority process to
+ be preempted even if it is in kernel mode executing a system call.
+ This allows applications to run more reliably even when the system is
+ under load.
+
+ Say Y here if you are building a kernel for a desktop, embedded
+ real-time system. Say N if you are unsure.
+
Kernel math emulation
CONFIG_MATH_EMULATION
Linux can emulate a math coprocessor (used for floating point
\
 
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