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SubjectRe: [PATCH] x86: Distinguish TLB shootdown interrupts from other functions call interrupts
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Hi Alex,

thank you for the review.

>> sum += irq_stats(cpu)->irq_call_count;
>> - sum += irq_stats(cpu)->irq_tlb_count;
>> + /* irq_tlb_count is already added to irq_call_count */
>
>redundant comments here?

>> @@ -98,6 +98,9 @@ static void flush_tlb_func(void *info)
>> {
>> struct flush_tlb_info *f = info;
>>
>> + /* irq_call_cnt is also incremented; be subtracted on display */
>
>If is it better to move above explanation to irq_call_cnt definition place: harirq.h?

Agreed.

In the patch below, I reduced the redundant comments.

--
As TLB shootdown requests to other CPU cores are now using function call
interrupts, TLB shootdowns entry in /proc/interrupts is always shown as 0.

This behavior change was introduced by commit 52aec3308db8 ("x86/tlb:
replace INVALIDATE_TLB_VECTOR by CALL_FUNCTION_VECTOR").

This patch reverts TLB shootdowns entry in /proc/interrupts to count TLB
shootdowns separately from the other function call interrupts.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alex Shi <alex.shi@intel.com>
---
arch/x86/include/asm/hardirq.h | 2 ++
arch/x86/kernel/irq.c | 4 ++--
arch/x86/mm/tlb.c | 2 ++
3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index d3895db..e34b252 100644
--- a/arch/x86/include/asm/hardirq.h
+++ b/arch/x86/include/asm/hardirq.h
@@ -18,6 +18,8 @@ typedef struct {
#ifdef CONFIG_SMP
unsigned int irq_resched_count;
unsigned int irq_call_count;
+ /* irq_tlb_count is double-counted in irq_call_count, so it must be
+ subtracted from irq_call_count when displaying irq_call_count */
unsigned int irq_tlb_count;
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index d44f782..e4595f1 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -92,7 +92,8 @@ int arch_show_interrupts(struct seq_file *p, int prec)
seq_printf(p, " Rescheduling interrupts\n");
seq_printf(p, "%*s: ", prec, "CAL");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
+ seq_printf(p, "%10u ", irq_stats(j)->irq_call_count -
+ irq_stats(j)->irq_tlb_count);
seq_printf(p, " Function call interrupts\n");
seq_printf(p, "%*s: ", prec, "TLB");
for_each_online_cpu(j)
@@ -147,7 +148,6 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
#ifdef CONFIG_SMP
sum += irq_stats(cpu)->irq_resched_count;
sum += irq_stats(cpu)->irq_call_count;
- sum += irq_stats(cpu)->irq_tlb_count;
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
sum += irq_stats(cpu)->irq_thermal_count;
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 613cd83..2d6d8ed 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -98,6 +98,8 @@ static void flush_tlb_func(void *info)
{
struct flush_tlb_info *f = info;

+ inc_irq_stat(irq_tlb_count);
+
if (f->flush_mm != this_cpu_read(cpu_tlbstate.active_mm))
return;



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