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Subject[RFC][PATCH] Ingo's smptimers patch experiment
Hi Ingo,

I ported your smptimers patch to 2.5.3 and experimented with
it a little bit. Basically I am curious about why we
we need to call run_all_timers() (which runs timers for all
CPUs) through the timer bh if locking fails in run_local_timers().
I experimented with a per-cpu tasklet to run only that CPU's
timers and it seems to work. I tested UP and SMP kernels in a
4way x86 box with LTP and chat benchmark.

Is there something that I am missing here ? A subtle race or
something that may result in losing firing of timers, perhaps ?

My experimental patch is included below.

Thanks
Dipankar
--
Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.

smptimers-2.5.3-2.patch
-----------------------

diff -urN linux-2.5.3/arch/i386/kernel/apic.c linux-2.5.3-smptimers/arch/i386/kernel/apic.c
--- linux-2.5.3/arch/i386/kernel/apic.c Tue Jan 29 02:42:04 2002
+++ linux-2.5.3-smptimers/arch/i386/kernel/apic.c Wed Feb 6 14:39:01 2002
@@ -1060,7 +1060,9 @@
irq_enter(cpu, 0);
smp_local_timer_interrupt(&regs);
irq_exit(cpu, 0);
-
+#if CONFIG_SMP
+ run_local_timers();
+#endif
if (softirq_pending(cpu))
do_softirq();
}
diff -urN linux-2.5.3/arch/i386/mm/fault.c linux-2.5.3-smptimers/arch/i386/mm/fault.c
--- linux-2.5.3/arch/i386/mm/fault.c Tue Jan 8 02:25:17 2002
+++ linux-2.5.3-smptimers/arch/i386/mm/fault.c Wed Feb 6 14:39:01 2002
@@ -94,16 +94,12 @@
goto bad_area;
}

-extern spinlock_t timerlist_lock;
-
/*
* Unlock any spinlocks which will prevent us from getting the
- * message out (timerlist_lock is acquired through the
- * console unblank code)
+ * message out
*/
void bust_spinlocks(int yes)
{
- spin_lock_init(&timerlist_lock);
if (yes) {
oops_in_progress = 1;
#ifdef CONFIG_SMP
diff -urN linux-2.5.3/arch/sparc/kernel/irq.c linux-2.5.3-smptimers/arch/sparc/kernel/irq.c
--- linux-2.5.3/arch/sparc/kernel/irq.c Mon Jan 14 23:40:43 2002
+++ linux-2.5.3-smptimers/arch/sparc/kernel/irq.c Wed Feb 6 14:39:01 2002
@@ -73,7 +73,7 @@
prom_halt();
}

-void (*init_timers)(void (*)(int, void *,struct pt_regs *)) =
+void (*sparc_init_timers)(void (*)(int, void *,struct pt_regs *)) =
(void (*)(void (*)(int, void *,struct pt_regs *))) irq_panic;

/*
diff -urN linux-2.5.3/arch/sparc/kernel/sun4c_irq.c linux-2.5.3-smptimers/arch/sparc/kernel/sun4c_irq.c
--- linux-2.5.3/arch/sparc/kernel/sun4c_irq.c Fri Apr 27 10:47:26 2001
+++ linux-2.5.3-smptimers/arch/sparc/kernel/sun4c_irq.c Wed Feb 6 14:39:01 2002
@@ -143,7 +143,7 @@
/* Errm.. not sure how to do this.. */
}

-static void __init sun4c_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
+static void __init sun4c_sparc_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
{
int irq;

@@ -221,7 +221,7 @@
BTFIXUPSET_CALL(clear_profile_irq, sun4c_clear_profile_irq, BTFIXUPCALL_NOP);
BTFIXUPSET_CALL(load_profile_irq, sun4c_load_profile_irq, BTFIXUPCALL_NOP);
BTFIXUPSET_CALL(__irq_itoa, sun4m_irq_itoa, BTFIXUPCALL_NORM);
- init_timers = sun4c_init_timers;
+ sparc_init_timers = sun4c_sparc_init_timers;
#ifdef CONFIG_SMP
BTFIXUPSET_CALL(set_cpu_int, sun4c_nop, BTFIXUPCALL_NOP);
BTFIXUPSET_CALL(clear_cpu_int, sun4c_nop, BTFIXUPCALL_NOP);
diff -urN linux-2.5.3/arch/sparc/kernel/sun4d_irq.c linux-2.5.3-smptimers/arch/sparc/kernel/sun4d_irq.c
--- linux-2.5.3/arch/sparc/kernel/sun4d_irq.c Mon Jan 14 23:40:44 2002
+++ linux-2.5.3-smptimers/arch/sparc/kernel/sun4d_irq.c Wed Feb 6 14:39:01 2002
@@ -436,7 +436,7 @@
bw_set_prof_limit(cpu, limit);
}

-static void __init sun4d_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
+static void __init sun4d_sparc_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
{
int irq;
extern struct prom_cpuinfo linux_cpus[NR_CPUS];
@@ -547,7 +547,7 @@
BTFIXUPSET_CALL(clear_profile_irq, sun4d_clear_profile_irq, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(load_profile_irq, sun4d_load_profile_irq, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(__irq_itoa, sun4d_irq_itoa, BTFIXUPCALL_NORM);
- init_timers = sun4d_init_timers;
+ sparc_init_timers = sun4d_sparc_init_timers;
#ifdef CONFIG_SMP
BTFIXUPSET_CALL(set_cpu_int, sun4d_set_cpu_int, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(clear_cpu_int, sun4d_clear_ipi, BTFIXUPCALL_NOP);
diff -urN linux-2.5.3/arch/sparc/kernel/sun4m_irq.c linux-2.5.3-smptimers/arch/sparc/kernel/sun4m_irq.c
--- linux-2.5.3/arch/sparc/kernel/sun4m_irq.c Fri Apr 27 10:47:26 2001
+++ linux-2.5.3-smptimers/arch/sparc/kernel/sun4m_irq.c Wed Feb 6 14:39:01 2002
@@ -223,7 +223,7 @@
return buff;
}

-static void __init sun4m_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
+static void __init sun4m_sparc_init_timers(void (*counter_fn)(int, void *, struct pt_regs *))
{
int reg_count, irq, cpu;
struct linux_prom_registers cnt_regs[PROMREG_MAX];
@@ -374,7 +374,7 @@
BTFIXUPSET_CALL(clear_profile_irq, sun4m_clear_profile_irq, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(load_profile_irq, sun4m_load_profile_irq, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(__irq_itoa, sun4m_irq_itoa, BTFIXUPCALL_NORM);
- init_timers = sun4m_init_timers;
+ sparc_init_timers = sun4m_sparc_init_timers;
#ifdef CONFIG_SMP
BTFIXUPSET_CALL(set_cpu_int, sun4m_send_ipi, BTFIXUPCALL_NORM);
BTFIXUPSET_CALL(clear_cpu_int, sun4m_clear_ipi, BTFIXUPCALL_NORM);
diff -urN linux-2.5.3/arch/sparc/kernel/time.c linux-2.5.3-smptimers/arch/sparc/kernel/time.c
--- linux-2.5.3/arch/sparc/kernel/time.c Thu Jan 24 04:58:39 2002
+++ linux-2.5.3-smptimers/arch/sparc/kernel/time.c Wed Feb 6 14:39:01 2002
@@ -379,7 +379,7 @@
else
clock_probe();

- init_timers(timer_interrupt);
+ sparc_init_timers(timer_interrupt);

#ifdef CONFIG_SUN4
if(idprom->id_machtype == (SM_SUN4 | SM_4_330)) {
diff -urN linux-2.5.3/arch/sparc64/kernel/irq.c linux-2.5.3-smptimers/arch/sparc64/kernel/irq.c
--- linux-2.5.3/arch/sparc64/kernel/irq.c Mon Jan 14 23:40:44 2002
+++ linux-2.5.3-smptimers/arch/sparc64/kernel/irq.c Wed Feb 6 14:39:01 2002
@@ -1027,7 +1027,7 @@
}

/* This is gets the master TICK_INT timer going. */
-void init_timers(void (*cfunc)(int, void *, struct pt_regs *),
+void sparc_init_timers(void (*cfunc)(int, void *, struct pt_regs *),
unsigned long *clock)
{
unsigned long pstate;
diff -urN linux-2.5.3/arch/sparc64/kernel/time.c linux-2.5.3-smptimers/arch/sparc64/kernel/time.c
--- linux-2.5.3/arch/sparc64/kernel/time.c Thu Jan 24 04:58:39 2002
+++ linux-2.5.3-smptimers/arch/sparc64/kernel/time.c Wed Feb 6 20:50:27 2002
@@ -595,7 +595,7 @@
__restore_flags(flags);
}

-extern void init_timers(void (*func)(int, void *, struct pt_regs *),
+extern void sparc_init_timers(void (*func)(int, void *, struct pt_regs *),
unsigned long *);

void __init time_init(void)
@@ -606,7 +606,7 @@
*/
unsigned long clock;

- init_timers(timer_interrupt, &clock);
+ sparc_init_timers(timer_interrupt, &clock);
timer_ticks_per_usec_quotient = ((1UL<<32) / (clock / 1000020));
}

diff -urN linux-2.5.3/drivers/net/eepro100.c linux-2.5.3-smptimers/drivers/net/eepro100.c
--- linux-2.5.3/drivers/net/eepro100.c Tue Jan 8 23:04:50 2002
+++ linux-2.5.3-smptimers/drivers/net/eepro100.c Wed Feb 6 14:39:01 2002
@@ -1123,9 +1123,6 @@
/* We must continue to monitor the media. */
sp->timer.expires = RUN_AT(2*HZ); /* 2.0 sec. */
add_timer(&sp->timer);
-#if defined(timer_exit)
- timer_exit(&sp->timer);
-#endif
}

static void speedo_show_state(struct net_device *dev)
diff -urN linux-2.5.3/include/asm-sparc/irq.h linux-2.5.3-smptimers/include/asm-sparc/irq.h
--- linux-2.5.3/include/asm-sparc/irq.h Tue Aug 29 09:50:03 2000
+++ linux-2.5.3-smptimers/include/asm-sparc/irq.h Wed Feb 6 14:39:01 2002
@@ -45,7 +45,7 @@
#define clear_profile_irq(cpu) BTFIXUP_CALL(clear_profile_irq)(cpu)
#define load_profile_irq(cpu,limit) BTFIXUP_CALL(load_profile_irq)(cpu,limit)

-extern void (*init_timers)(void (*lvl10_irq)(int, void *, struct pt_regs *));
+extern void (*sparc_init_timers)(void (*lvl10_irq)(int, void *, struct pt_regs *));
extern void claim_ticker14(void (*irq_handler)(int, void *, struct pt_regs *),
int irq,
unsigned int timeout);
diff -urN linux-2.5.3/include/asm-sparc64/irq.h linux-2.5.3-smptimers/include/asm-sparc64/irq.h
--- linux-2.5.3/include/asm-sparc64/irq.h Thu Jan 24 04:58:40 2002
+++ linux-2.5.3-smptimers/include/asm-sparc64/irq.h Wed Feb 6 14:39:01 2002
@@ -113,7 +113,7 @@
extern void disable_irq(unsigned int);
#define disable_irq_nosync disable_irq
extern void enable_irq(unsigned int);
-extern void init_timers(void (*lvl10_irq)(int, void *, struct pt_regs *),
+extern void sparc_init_timers(void (*lvl10_irq)(int, void *, struct pt_regs *),
unsigned long *);
extern unsigned int build_irq(int pil, int inofixup, unsigned long iclr, unsigned long imap);
extern unsigned int sbus_build_irq(void *sbus, unsigned int ino);
diff -urN linux-2.5.3/include/linux/smp.h linux-2.5.3-smptimers/include/linux/smp.h
--- linux-2.5.3/include/linux/smp.h Wed Jan 30 11:11:12 2002
+++ linux-2.5.3-smptimers/include/linux/smp.h Wed Feb 6 19:01:32 2002
@@ -76,7 +76,8 @@
/*
* These macros fold the SMP functionality into a single CPU system
*/
-
+
+#define NR_CPUS 1
#define smp_num_cpus 1
#define smp_processor_id() 0
#define hard_smp_processor_id() 0
diff -urN linux-2.5.3/include/linux/timer.h linux-2.5.3-smptimers/include/linux/timer.h
--- linux-2.5.3/include/linux/timer.h Wed Jan 30 11:11:11 2002
+++ linux-2.5.3-smptimers/include/linux/timer.h Wed Feb 6 19:01:32 2002
@@ -1,9 +1,6 @@
#ifndef _LINUX_TIMER_H
#define _LINUX_TIMER_H

-#include <linux/config.h>
-#include <linux/list.h>
-
/*
* In Linux 2.4, static timers have been removed from the kernel.
* Timers may be dynamically created and destroyed, and should be initialized
@@ -13,22 +10,80 @@
* timeouts. You can use this field to distinguish between the different
* invocations.
*/
+
+#include <linux/config.h>
+#include <linux/smp.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/cache.h>
+
+/*
+ * Event timer code
+ */
+#define TVN_BITS 6
+#define TVR_BITS 8
+#define TVN_SIZE (1 << TVN_BITS)
+#define TVR_SIZE (1 << TVR_BITS)
+#define TVN_MASK (TVN_SIZE - 1)
+#define TVR_MASK (TVR_SIZE - 1)
+
+typedef struct tvec_s {
+ int index;
+ struct list_head vec[TVN_SIZE];
+} tvec_t;
+
+typedef struct tvec_root_s {
+ int index;
+ struct list_head vec[TVR_SIZE];
+} tvec_root_t;
+
+#define NOOF_TVECS 5
+
+typedef struct timer_list timer_t;
+
+struct tvec_t_base_s {
+ spinlock_t lock;
+ unsigned long timer_jiffies;
+ volatile timer_t * volatile running_timer;
+ tvec_root_t tv1;
+ tvec_t tv2;
+ tvec_t tv3;
+ tvec_t tv4;
+ tvec_t tv5;
+} ____cacheline_aligned_in_smp;
+
+typedef struct tvec_t_base_s tvec_base_t;
+
+/*
+ * This is the new and improved way of handling timers.
+ *
+ * The "data" field is in case you want to use the same
+ * timeout function for several timeouts. You can use this
+ * to distinguish between the different invocations.
+ */
struct timer_list {
struct list_head list;
unsigned long expires;
unsigned long data;
void (*function)(unsigned long);
+ tvec_base_t *base;
};

-extern void add_timer(struct timer_list * timer);
-extern int del_timer(struct timer_list * timer);
+extern void add_timer(timer_t * timer);
+extern int del_timer(timer_t * timer);

#ifdef CONFIG_SMP
-extern int del_timer_sync(struct timer_list * timer);
+extern int del_timer_sync(timer_t * timer);
extern void sync_timers(void);
+#define timer_enter(base, t) do { base->running_timer = t; mb(); } while (0)
+#define timer_exit(base) do { base->running_timer = NULL; } while (0)
+#define timer_is_running(base,t) (base->running_timer == t)
+#define timer_synchronize(base,t) while (timer_is_running(base,t)) barrier()
#else
#define del_timer_sync(t) del_timer(t)
#define sync_timers() do { } while (0)
+#define timer_enter(base,t) do { } while (0)
+#define timer_exit(base) do { } while (0)
#endif

/*
@@ -38,17 +93,33 @@
* If the timer is known to be not pending (ie, in the handler), mod_timer
* is less efficient than a->expires = b; add_timer(a).
*/
-int mod_timer(struct timer_list *timer, unsigned long expires);
+int mod_timer(timer_t *timer, unsigned long expires);

extern void it_real_fn(unsigned long);

-static inline void init_timer(struct timer_list * timer)
+extern void init_timers(void);
+extern void run_local_timers(void);
+
+extern tvec_base_t tvec_bases[NR_CPUS];
+
+static inline void init_timer(timer_t * timer)
{
timer->list.next = timer->list.prev = NULL;
+ timer->base = tvec_bases + 0;
}

-static inline int timer_pending (const struct timer_list * timer)
+#define TIMER_DEBUG 0
+#if TIMER_DEBUG
+# define CHECK_BASE(base) \
+ if (base && ((base < tvec_bases) || (base >= tvec_bases + NR_CPUS))) \
+ BUG()
+#else
+# define CHECK_BASE(base)
+#endif
+
+static inline int timer_pending(const timer_t * timer)
{
+ CHECK_BASE(timer->base);
return timer->list.next != NULL;
}

diff -urN linux-2.5.3/kernel/ksyms.c linux-2.5.3-smptimers/kernel/ksyms.c
--- linux-2.5.3/kernel/ksyms.c Wed Jan 30 00:17:10 2002
+++ linux-2.5.3-smptimers/kernel/ksyms.c Wed Feb 6 14:39:01 2002
@@ -383,6 +383,7 @@
EXPORT_SYMBOL(del_timer_sync);
#endif
EXPORT_SYMBOL(mod_timer);
+EXPORT_SYMBOL(tvec_bases);
EXPORT_SYMBOL(tq_timer);
EXPORT_SYMBOL(tq_immediate);

diff -urN linux-2.5.3/kernel/sched.c linux-2.5.3-smptimers/kernel/sched.c
--- linux-2.5.3/kernel/sched.c Tue Jan 29 04:42:47 2002
+++ linux-2.5.3-smptimers/kernel/sched.c Wed Feb 6 14:39:01 2002
@@ -1322,7 +1322,7 @@
__restore_flags(flags);
}

-extern void init_timervecs(void);
+extern void init_timers(void);
extern void timer_bh(void);
extern void tqueue_bh(void);
extern void immediate_bh(void);
@@ -1361,8 +1361,7 @@
rq->idle = current;
wake_up_process(current);

- init_timervecs();
- init_bh(TIMER_BH, timer_bh);
+ init_timers();
init_bh(TQUEUE_BH, tqueue_bh);
init_bh(IMMEDIATE_BH, immediate_bh);

diff -urN linux-2.5.3/kernel/timer.c linux-2.5.3-smptimers/kernel/timer.c
--- linux-2.5.3/kernel/timer.c Wed Jan 16 04:03:55 2002
+++ linux-2.5.3-smptimers/kernel/timer.c Wed Feb 6 20:25:08 2002
@@ -13,10 +13,15 @@
* serialize accesses to xtime/lost_ticks).
* Copyright (C) 1998 Andrea Arcangeli
* 1999-03-10 Improved NTP compatibility by Ulrich Windl
+ * 2000-10-05 Implemented scalable SMP per-CPU timer handling.
+ * Copyright (C) 2000 Ingo Molnar
+ * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
*/

#include <linux/config.h>
+
#include <linux/mm.h>
+#include <linux/init.h>
#include <linux/timex.h>
#include <linux/delay.h>
#include <linux/smp_lock.h>
@@ -73,83 +78,56 @@
unsigned long prof_len;
unsigned long prof_shift;

-/*
- * Event timer code
- */
-#define TVN_BITS 6
-#define TVR_BITS 8
-#define TVN_SIZE (1 << TVN_BITS)
-#define TVR_SIZE (1 << TVR_BITS)
-#define TVN_MASK (TVN_SIZE - 1)
-#define TVR_MASK (TVR_SIZE - 1)
-
-struct timer_vec {
- int index;
- struct list_head vec[TVN_SIZE];
-};
-
-struct timer_vec_root {
- int index;
- struct list_head vec[TVR_SIZE];
-};
-
-static struct timer_vec tv5;
-static struct timer_vec tv4;
-static struct timer_vec tv3;
-static struct timer_vec tv2;
-static struct timer_vec_root tv1;
-
-static struct timer_vec * const tvecs[] = {
- (struct timer_vec *)&tv1, &tv2, &tv3, &tv4, &tv5
-};
+tvec_base_t tvec_bases[NR_CPUS] __cacheline_aligned;

-#define NOOF_TVECS (sizeof(tvecs) / sizeof(tvecs[0]))
+/* To be changed to a per-CPU type with Rusty's patch */
+struct timer_tlet {
+ struct tasklet_struct tasklet;
+} ____cacheline_aligned_in_smp;

-void init_timervecs (void)
-{
- int i;
+static struct timer_tlet timer_tlets[NR_CPUS] __cacheline_aligned;

- for (i = 0; i < TVN_SIZE; i++) {
- INIT_LIST_HEAD(tv5.vec + i);
- INIT_LIST_HEAD(tv4.vec + i);
- INIT_LIST_HEAD(tv3.vec + i);
- INIT_LIST_HEAD(tv2.vec + i);
- }
- for (i = 0; i < TVR_SIZE; i++)
- INIT_LIST_HEAD(tv1.vec + i);
-}
+/* jiffies at the most recent update of wall time */
+unsigned long wall_jiffies;

-static unsigned long timer_jiffies;
+/*
+ * This spinlock protect us from races in SMP while playing with xtime. -arca
+ */
+rwlock_t xtime_lock = RW_LOCK_UNLOCKED;

-static inline void internal_add_timer(struct timer_list *timer)
+/*
+ * This is the 'global' timer BH. This gets called only if one of
+ * the local timer interrupts couldnt run timers.
+ */
+static inline void internal_add_timer(tvec_base_t *base, timer_t *timer)
{
/*
* must be cli-ed when calling this
*/
unsigned long expires = timer->expires;
- unsigned long idx = expires - timer_jiffies;
+ unsigned long idx = expires - base->timer_jiffies;
struct list_head * vec;

if (idx < TVR_SIZE) {
int i = expires & TVR_MASK;
- vec = tv1.vec + i;
+ vec = base->tv1.vec + i;
} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
int i = (expires >> TVR_BITS) & TVN_MASK;
- vec = tv2.vec + i;
+ vec = base->tv2.vec + i;
} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
- vec = tv3.vec + i;
+ vec = base->tv3.vec + i;
} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
- vec = tv4.vec + i;
+ vec = base->tv4.vec + i;
} else if ((signed long) idx < 0) {
/* can happen if you add a timer with expires == jiffies,
* or you set a timer to go off in the past
*/
- vec = tv1.vec + tv1.index;
+ vec = base->tv1.vec + base->tv1.index;
} else if (idx <= 0xffffffffUL) {
int i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
- vec = tv5.vec + i;
+ vec = base->tv5.vec + i;
} else {
/* Can only get here on architectures with 64-bit jiffies */
INIT_LIST_HEAD(&timer->list);
@@ -161,37 +139,27 @@
list_add(&timer->list, vec->prev);
}

-/* Initialize both explicitly - let's try to have them in the same cache line */
-spinlock_t timerlist_lock = SPIN_LOCK_UNLOCKED;
-
-#ifdef CONFIG_SMP
-volatile struct timer_list * volatile running_timer;
-#define timer_enter(t) do { running_timer = t; mb(); } while (0)
-#define timer_exit() do { running_timer = NULL; } while (0)
-#define timer_is_running(t) (running_timer == t)
-#define timer_synchronize(t) while (timer_is_running(t)) barrier()
-#else
-#define timer_enter(t) do { } while (0)
-#define timer_exit() do { } while (0)
-#endif
-
-void add_timer(struct timer_list *timer)
+void add_timer(timer_t *timer)
{
+ tvec_base_t * base = tvec_bases + smp_processor_id();
unsigned long flags;

- spin_lock_irqsave(&timerlist_lock, flags);
+ CHECK_BASE(base);
+ CHECK_BASE(timer->base);
+ spin_lock_irqsave(&base->lock, flags);
if (timer_pending(timer))
goto bug;
- internal_add_timer(timer);
- spin_unlock_irqrestore(&timerlist_lock, flags);
+ internal_add_timer(base, timer);
+ timer->base = base;
+ spin_unlock_irqrestore(&base->lock, flags);
return;
bug:
- spin_unlock_irqrestore(&timerlist_lock, flags);
+ spin_unlock_irqrestore(&base->lock, flags);
printk("bug: kernel timer added twice at %p.\n",
__builtin_return_address(0));
}

-static inline int detach_timer (struct timer_list *timer)
+static inline int detach_timer(timer_t *timer)
{
if (!timer_pending(timer))
return 0;
@@ -199,28 +167,81 @@
return 1;
}

-int mod_timer(struct timer_list *timer, unsigned long expires)
+/*
+ * mod_timer() has subtle locking semantics because parallel
+ * calls to it must happen serialized.
+ */
+int mod_timer(timer_t *timer, unsigned long expires)
{
- int ret;
+ tvec_base_t *old_base, *new_base;
unsigned long flags;
+ int ret;
+
+ new_base = tvec_bases + smp_processor_id();
+ CHECK_BASE(new_base);
+
+ __save_flags(flags);
+ __cli();
+repeat:
+ old_base = timer->base;
+ CHECK_BASE(old_base);
+
+ /*
+ * Prevent deadlocks via ordering by old_base < new_base.
+ */
+ if (old_base && (new_base != old_base)) {
+ if (old_base < new_base) {
+ spin_lock(&new_base->lock);
+ spin_lock(&old_base->lock);
+ } else {
+ spin_lock(&old_base->lock);
+ spin_lock(&new_base->lock);
+ }
+ /*
+ * Subtle, we rely on timer->base being always
+ * valid and being updated atomically.
+ */
+ if (timer->base != old_base) {
+ spin_unlock(&new_base->lock);
+ spin_unlock(&old_base->lock);
+ goto repeat;
+ }
+ } else
+ spin_lock(&new_base->lock);

- spin_lock_irqsave(&timerlist_lock, flags);
timer->expires = expires;
ret = detach_timer(timer);
- internal_add_timer(timer);
- spin_unlock_irqrestore(&timerlist_lock, flags);
+ internal_add_timer(new_base, timer);
+ timer->base = new_base;
+
+
+ if (old_base && (new_base != old_base))
+ spin_unlock(&old_base->lock);
+ spin_unlock_irqrestore(&new_base->lock, flags);
+
return ret;
}

-int del_timer(struct timer_list * timer)
+int del_timer(timer_t * timer)
{
- int ret;
unsigned long flags;
+ tvec_base_t * base;
+ int ret;

- spin_lock_irqsave(&timerlist_lock, flags);
+ CHECK_BASE(timer->base);
+ if (!timer->base)
+ return 0;
+repeat:
+ base = timer->base;
+ spin_lock_irqsave(&base->lock, flags);
+ if (base != timer->base) {
+ spin_unlock_irqrestore(&base->lock, flags);
+ goto repeat;
+ }
ret = detach_timer(timer);
timer->list.next = timer->list.prev = NULL;
- spin_unlock_irqrestore(&timerlist_lock, flags);
+ spin_unlock_irqrestore(&base->lock, flags);
+
return ret;
}

@@ -238,24 +259,34 @@
* (for reference counting).
*/

-int del_timer_sync(struct timer_list * timer)
+int del_timer_sync(timer_t * timer)
{
+ tvec_base_t * base;
int ret = 0;

+ CHECK_BASE(timer->base);
+ if (!timer->base)
+ return 0;
for (;;) {
unsigned long flags;
int running;

- spin_lock_irqsave(&timerlist_lock, flags);
+repeat:
+ base = timer->base;
+ spin_lock_irqsave(&base->lock, flags);
+ if (base != timer->base) {
+ spin_unlock_irqrestore(&base->lock, flags);
+ goto repeat;
+ }
ret += detach_timer(timer);
timer->list.next = timer->list.prev = 0;
- running = timer_is_running(timer);
- spin_unlock_irqrestore(&timerlist_lock, flags);
+ running = timer_is_running(base, timer);
+ spin_unlock_irqrestore(&base->lock, flags);

if (!running)
break;

- timer_synchronize(timer);
+ timer_synchronize(base, timer);
}

return ret;
@@ -263,7 +294,7 @@
#endif


-static inline void cascade_timers(struct timer_vec *tv)
+static void cascade(tvec_base_t *base, tvec_t *tv)
{
/* cascade all the timers from tv up one level */
struct list_head *head, *curr, *next;
@@ -275,54 +306,68 @@
* detach them individually, just clear the list afterwards.
*/
while (curr != head) {
- struct timer_list *tmp;
+ timer_t *tmp;

- tmp = list_entry(curr, struct timer_list, list);
+ tmp = list_entry(curr, timer_t, list);
+ CHECK_BASE(tmp->base);
+ if (tmp->base != base)
+ BUG();
next = curr->next;
list_del(curr); // not needed
- internal_add_timer(tmp);
+ internal_add_timer(base, tmp);
curr = next;
}
INIT_LIST_HEAD(head);
tv->index = (tv->index + 1) & TVN_MASK;
}

-static inline void run_timer_list(void)
+static void __run_timers(tvec_base_t *base)
{
- spin_lock_irq(&timerlist_lock);
- while ((long)(jiffies - timer_jiffies) >= 0) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&base->lock, flags);
+ while ((long)(jiffies - base->timer_jiffies) >= 0) {
struct list_head *head, *curr;
- if (!tv1.index) {
- int n = 1;
- do {
- cascade_timers(tvecs[n]);
- } while (tvecs[n]->index == 1 && ++n < NOOF_TVECS);
+
+ /*
+ * Cascade timers:
+ */
+ if (!base->tv1.index) {
+ cascade(base, &base->tv2);
+ if (base->tv2.index == 1) {
+ cascade(base, &base->tv3);
+ if (base->tv3.index == 1) {
+ cascade(base, &base->tv4);
+ if (base->tv4.index == 1)
+ cascade(base, &base->tv5);
+ }
+ }
}
repeat:
- head = tv1.vec + tv1.index;
+ head = base->tv1.vec + base->tv1.index;
curr = head->next;
if (curr != head) {
- struct timer_list *timer;
void (*fn)(unsigned long);
unsigned long data;
+ timer_t *timer;

- timer = list_entry(curr, struct timer_list, list);
+ timer = list_entry(curr, timer_t, list);
fn = timer->function;
- data= timer->data;
+ data = timer->data;

detach_timer(timer);
timer->list.next = timer->list.prev = NULL;
- timer_enter(timer);
- spin_unlock_irq(&timerlist_lock);
+ timer_enter(base, timer);
+ spin_unlock_irq(&base->lock);
fn(data);
- spin_lock_irq(&timerlist_lock);
- timer_exit();
+ spin_lock_irq(&base->lock);
+ timer_exit(base);
goto repeat;
}
- ++timer_jiffies;
- tv1.index = (tv1.index + 1) & TVR_MASK;
+ ++base->timer_jiffies;
+ base->tv1.index = (base->tv1.index + 1) & TVR_MASK;
}
- spin_unlock_irq(&timerlist_lock);
+ spin_unlock_irqrestore(&base->lock, flags);
}

spinlock_t tqueue_lock = SPIN_LOCK_UNLOCKED;
@@ -638,40 +683,86 @@
}
}

-/* jiffies at the most recent update of wall time */
-unsigned long wall_jiffies;
+static void run_timer_tasklet(unsigned long data)
+{
+ tvec_base_t *base = tvec_bases + smp_processor_id();
+ if ((long)(jiffies - base->timer_jiffies) >= 0)
+ __run_timers(base);
+}
+
+#ifndef CONFIG_X86
+/* Needed only for non-x86 for the time being *//
+static void run_all_timers(void)
+{
+ int i;
+
+ for (i = 0; i < smp_num_cpus; i++) {
+ tvec_base_t *base = tvec_bases + i;
+ if ((long)(jiffies - base->timer_jiffies) >= 0)
+ __run_timers(base);
+ }
+}
+#endif

/*
- * This spinlock protect us from races in SMP while playing with xtime. -arca
+ * Called by the local, per-CPU timer interrupt on SMP.
+ *
+ * This function has to do all sorts of locking to make legacy
+ * cli()-users and BH-disablers work. If locking doesnt succeed
+ * now then we fall back to TIMER_BH.
*/
-rwlock_t xtime_lock = RW_LOCK_UNLOCKED;
+void run_local_timers(void)
+{
+ int cpu = smp_processor_id();
+ tvec_base_t *base = tvec_bases + cpu;
+
+ if (in_interrupt())
+ goto out_mark;
+
+ local_bh_disable();
+ local_irq_disable();
+ if (!spin_trylock(&global_bh_lock))
+ goto out_enable_mark;
+
+ if (!hardirq_trylock(cpu))
+ goto out_unlock_enable_mark;
+
+ if ((long)(jiffies - base->timer_jiffies) >= 0)
+ __run_timers(base);
+
+ hardirq_endlock(cpu);
+ spin_unlock(&global_bh_lock);
+ local_irq_enable();
+ local_bh_enable();
+ return;
+
+out_unlock_enable_mark:
+ spin_unlock(&global_bh_lock);
+
+out_enable_mark:
+ local_irq_enable();
+ local_bh_enable();

-static inline void update_times(void)
+out_mark:
+ tasklet_hi_schedule(&timer_tlets[cpu].tasklet);
+}
+
+/*
+ * Called by the timer interrupt. xtime_lock must already be taken
+ * by the timer IRQ!
+ */
+static void update_times(void)
{
unsigned long ticks;

- /*
- * update_times() is run from the raw timer_bh handler so we
- * just know that the irqs are locally enabled and so we don't
- * need to save/restore the flags of the local CPU here. -arca
- */
- write_lock_irq(&xtime_lock);
-
ticks = jiffies - wall_jiffies;
if (ticks) {
wall_jiffies += ticks;
update_wall_time(ticks);
}
- write_unlock_irq(&xtime_lock);
calc_load(ticks);
}

-void timer_bh(void)
-{
- update_times();
- run_timer_list();
-}
-
void do_timer(struct pt_regs *regs)
{
(*(unsigned long *)&jiffies)++;
@@ -679,8 +770,18 @@
/* SMP process accounting uses the local APIC timer */

update_process_times(user_mode(regs));
+#ifdef CONFIG_X86
+ tasklet_hi_schedule(&timer_tlets[0].tasklet);
+#endif
#endif
+ /*
+ * Right now only x86-SMP calls run_local_timers() from a
+ * per-CPU interrupt.
+ */
+#ifndef CONFIG_X86
mark_bh(TIMER_BH);
+#endif
+ update_times();
if (TQ_ACTIVE(tq_timer))
mark_bh(TQUEUE_BH);
}
@@ -923,5 +1024,28 @@
return -EINTR;
}
return 0;
+}
+
+void __init init_timers(void)
+{
+ int i, j;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ tvec_base_t *base = tvec_bases + i;
+
+ spin_lock_init(&base->lock);
+ for (j = 0; j < TVN_SIZE; j++) {
+ INIT_LIST_HEAD(base->tv5.vec + j);
+ INIT_LIST_HEAD(base->tv4.vec + j);
+ INIT_LIST_HEAD(base->tv3.vec + j);
+ INIT_LIST_HEAD(base->tv2.vec + j);
+ }
+ for (j = 0; j < TVR_SIZE; j++)
+ INIT_LIST_HEAD(base->tv1.vec + j);
+ tasklet_init(&timer_tlets[i].tasklet, run_timer_tasklet, 0);
+ }
+#ifndef CONFIG_X86
+ init_bh(TIMER_BH, run_all_timers);
+#endif
}

-
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