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SubjectRe: [PATCH 00/11] x86: cpumask: some more cpumask cleanups - flush_tlb_*
Ingo Molnar wrote:
...
>> ====== Stack (-l 500)
>> 1 - allyesconfig-128
>> 2 - allyesconfig-4k
>>
>> .1. .2. ..final..
>> 0 +1032 1032 . flush_tlb_page
>> 0 +1024 1024 . kvm_reload_remote_mmus
>> 0 +1024 1024 . kvm_flush_remote_tlbs
>> 0 +1024 1024 . flush_tlb_mm
>> 0 +1024 1024 . flush_tlb_current_task
>
> Quite good! Can we fix those TLB flush cpumask uses too?

Here is one proposal. I don't like increasing PER_CPU area but eventually we
should be able to per_cpu_alloc the cpumasks so they only take up enough room
as needed. Also, it was unclear whether one scratch cpumask work suffice for
all three flush_tlb_* functions or a separate one for each was needed. I
went for the safe route and used one for each function.

An alternate approach might be to add a scratch cpumask to the smp_flush_state
struct. It already has one fixed cpumask_t (flush_cpumask) so this whole
struct should per_cpu_alloc'd. (And since it's cacheline_aligned, then a
per_cpu_alloc_aligned() will probably be needed?)

(btw, only 64-bit shown here, 32-bit needs similar changes.)

Thanks,
Mike

---
Subject: cpumask: remove cpumask_t from stack for flush_tlb_xxx
Remove the scratch cpumask_t from the stack for the flush_tlb_*
functions. Since we're disabling preemption, we can use a
one-per-cpu scratch cpumask. "Un-const" the cpumask pointer arg
in native_flush_tlb_others as one of the flush_others functions
(uv) changed the cpumask. I believe this is safe.

Signed-off-by: Mike Travis <travis@sgi.com>
---
arch/x86/include/asm/paravirt.h | 8 ++---
arch/x86/include/asm/tlbflush.h | 4 +-
arch/x86/include/asm/uv/uv_bau.h | 3 +-
arch/x86/kernel/tlb_64.c | 53 +++++++++++++++++++++------------------
arch/x86/kernel/tlb_uv.c | 12 ++++----
5 files changed, 43 insertions(+), 37 deletions(-)
--- linux-2.6-for-ingo.orig/arch/x86/include/asm/paravirt.h
+++ linux-2.6-for-ingo/arch/x86/include/asm/paravirt.h
@@ -244,7 +244,7 @@ struct pv_mmu_ops {
void (*flush_tlb_user)(void);
void (*flush_tlb_kernel)(void);
void (*flush_tlb_single)(unsigned long addr);
- void (*flush_tlb_others)(const cpumask_t *cpus, struct mm_struct *mm,
+ void (*flush_tlb_others)(struct cpumask *cpus, struct mm_struct *mm,
unsigned long va);

/* Hooks for allocating and freeing a pagetable top-level */
@@ -984,10 +984,10 @@ static inline void __flush_tlb_single(un
PVOP_VCALL1(pv_mmu_ops.flush_tlb_single, addr);
}

-static inline void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
- unsigned long va)
+static inline void flush_tlb_others(struct cpumask *cpumask,
+ struct mm_struct *mm, unsigned long va)
{
- PVOP_VCALL3(pv_mmu_ops.flush_tlb_others, &cpumask, mm, va);
+ PVOP_VCALL3(pv_mmu_ops.flush_tlb_others, cpumask, mm, va);
}

static inline int paravirt_pgd_alloc(struct mm_struct *mm)
--- linux-2.6-for-ingo.orig/arch/x86/include/asm/tlbflush.h
+++ linux-2.6-for-ingo/arch/x86/include/asm/tlbflush.h
@@ -142,7 +142,7 @@ static inline void flush_tlb_range(struc
flush_tlb_mm(vma->vm_mm);
}

-void native_flush_tlb_others(const cpumask_t *cpumask, struct mm_struct *mm,
+void native_flush_tlb_others(struct cpumask *cpumask, struct mm_struct *mm,
unsigned long va);

#define TLBSTATE_OK 1
@@ -166,7 +166,7 @@ static inline void reset_lazy_tlbstate(v
#endif /* SMP */

#ifndef CONFIG_PARAVIRT
-#define flush_tlb_others(mask, mm, va) native_flush_tlb_others(&mask, mm, va)
+#define flush_tlb_others(mask, mm, va) native_flush_tlb_others(mask, mm, va)
#endif

static inline void flush_tlb_kernel_range(unsigned long start,
--- linux-2.6-for-ingo.orig/arch/x86/include/asm/uv/uv_bau.h
+++ linux-2.6-for-ingo/arch/x86/include/asm/uv/uv_bau.h
@@ -325,7 +325,8 @@ static inline void bau_cpubits_clear(str
#define cpubit_isset(cpu, bau_local_cpumask) \
test_bit((cpu), (bau_local_cpumask).bits)

-extern int uv_flush_tlb_others(cpumask_t *, struct mm_struct *, unsigned long);
+extern int uv_flush_tlb_others(struct cpumask *, struct mm_struct *,
+ unsigned long);
extern void uv_bau_message_intr1(void);
extern void uv_bau_timeout_intr1(void);

--- linux-2.6-for-ingo.orig/arch/x86/kernel/tlb_64.c
+++ linux-2.6-for-ingo/arch/x86/kernel/tlb_64.c
@@ -157,14 +157,13 @@ out:
inc_irq_stat(irq_tlb_count);
}

-void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
+void native_flush_tlb_others(struct cpumask *cpumask, struct mm_struct *mm,
unsigned long va)
{
int sender;
union smp_flush_state *f;
- cpumask_t cpumask = *cpumaskp;

- if (is_uv_system() && uv_flush_tlb_others(&cpumask, mm, va))
+ if (is_uv_system() && uv_flush_tlb_others(cpumask, mm, va))
return;

/* Caller has disabled preemption */
@@ -180,7 +179,7 @@ void native_flush_tlb_others(const cpuma

f->flush_mm = mm;
f->flush_va = va;
- cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask);
+ cpumask_or(&f->flush_cpumask, cpumask, &f->flush_cpumask);

/*
* Make the above memory operations globally visible before
@@ -191,9 +190,9 @@ void native_flush_tlb_others(const cpuma
* We have to send the IPI only to
* CPUs affected.
*/
- send_IPI_mask(&cpumask, INVALIDATE_TLB_VECTOR_START + sender);
+ send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender);

- while (!cpus_empty(f->flush_cpumask))
+ while (!cpumask_empty(&f->flush_cpumask))
cpu_relax();

f->flush_mm = NULL;
@@ -212,28 +211,32 @@ static int __cpuinit init_smp_flush(void
}
core_initcall(init_smp_flush);

+static DEFINE_PER_CPU(cpumask_t, flush_tlb_task_cpumask);
+
void flush_tlb_current_task(void)
{
struct mm_struct *mm = current->mm;
- cpumask_t cpu_mask;
+ struct cpumask *cpu_mask;

- preempt_disable();
- cpu_mask = mm->cpu_vm_mask;
- cpu_clear(smp_processor_id(), cpu_mask);
+ cpu_mask = &get_cpu_var(flush_tlb_task_cpumask);
+ cpumask_copy(cpu_mask, &mm->cpu_vm_mask);
+ cpumask_clear_cpu(smp_processor_id(), cpu_mask);

local_flush_tlb();
- if (!cpus_empty(cpu_mask))
+ if (!cpumask_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
- preempt_enable();
+ put_cpu_var(flush_tlb_task_cpumask);
}

+static DEFINE_PER_CPU(cpumask_t, flush_tlb_mm_cpumask);
+
void flush_tlb_mm(struct mm_struct *mm)
{
- cpumask_t cpu_mask;
+ struct cpumask * cpu_mask;

- preempt_disable();
- cpu_mask = mm->cpu_vm_mask;
- cpu_clear(smp_processor_id(), cpu_mask);
+ cpu_mask = &get_cpu_var(flush_tlb_mm_cpumask);
+ cpumask_copy(cpu_mask, &mm->cpu_vm_mask);
+ cpumask_clear_cpu(smp_processor_id(), cpu_mask);

if (current->active_mm == mm) {
if (current->mm)
@@ -241,20 +244,22 @@ void flush_tlb_mm(struct mm_struct *mm)
else
leave_mm(smp_processor_id());
}
- if (!cpus_empty(cpu_mask))
+ if (!cpumask_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);

- preempt_enable();
+ put_cpu_var(flush_tlb_mm_cpumask);
}

+static DEFINE_PER_CPU(cpumask_t, flush_tlb_page_cpumask);
+
void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
{
struct mm_struct *mm = vma->vm_mm;
- cpumask_t cpu_mask;
+ struct cpumask *cpu_mask;

- preempt_disable();
- cpu_mask = mm->cpu_vm_mask;
- cpu_clear(smp_processor_id(), cpu_mask);
+ cpu_mask = &get_cpu_var(flush_tlb_page_cpumask);
+ cpumask_copy(cpu_mask, &mm->cpu_vm_mask);
+ cpumask_clear_cpu(smp_processor_id(), cpu_mask);

if (current->active_mm == mm) {
if (current->mm)
@@ -263,10 +268,10 @@ void flush_tlb_page(struct vm_area_struc
leave_mm(smp_processor_id());
}

- if (!cpus_empty(cpu_mask))
+ if (!cpumask_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, va);

- preempt_enable();
+ put_cpu_var(flush_tlb_page_cpumask);
}

static void do_flush_tlb_all(void *info)
--- linux-2.6-for-ingo.orig/arch/x86/kernel/tlb_uv.c
+++ linux-2.6-for-ingo/arch/x86/kernel/tlb_uv.c
@@ -216,7 +216,7 @@ static int uv_wait_completion(struct bau
* unchanged.
*/
int uv_flush_send_and_wait(int cpu, int this_blade, struct bau_desc *bau_desc,
- cpumask_t *cpumaskp)
+ struct cpumask *cpumaskp)
{
int completion_status = 0;
int right_shift;
@@ -263,13 +263,13 @@ int uv_flush_send_and_wait(int cpu, int
* Success, so clear the remote cpu's from the mask so we don't
* use the IPI method of shootdown on them.
*/
- for_each_cpu_mask(bit, *cpumaskp) {
+ for_each_cpu(bit, cpumaskp) {
blade = uv_cpu_to_blade_id(bit);
if (blade == this_blade)
continue;
- cpu_clear(bit, *cpumaskp);
+ cpumask_clear_cpu(bit, cpumaskp);
}
- if (!cpus_empty(*cpumaskp))
+ if (!cpumask_empty(cpumaskp))
return 0;
return 1;
}
@@ -296,7 +296,7 @@ int uv_flush_send_and_wait(int cpu, int
* Returns 1 if all remote flushing was done.
* Returns 0 if some remote flushing remains to be done.
*/
-int uv_flush_tlb_others(cpumask_t *cpumaskp, struct mm_struct *mm,
+int uv_flush_tlb_others(struct cpumask *cpumaskp, struct mm_struct *mm,
unsigned long va)
{
int i;
@@ -315,7 +315,7 @@ int uv_flush_tlb_others(cpumask_t *cpuma
bau_nodes_clear(&bau_desc->distribution, UV_DISTRIBUTION_SIZE);

i = 0;
- for_each_cpu_mask(bit, *cpumaskp) {
+ for_each_cpu(bit, cpumaskp) {
blade = uv_cpu_to_blade_id(bit);
BUG_ON(blade > (UV_DISTRIBUTION_SIZE - 1));
if (blade == this_blade) {

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