linux-kernel - Re: [PATCH] x86: Distinguish TLB shootdown interrupts from other functions call interrupts

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Date:	Fri, 21 Sep 2012 16:08:15 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com>
CC:	x86@...nel.org, yrl.pp-manager.tt@...achi.com,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86: Distinguish TLB shootdown interrupts from other
 functions call interrupts

>> 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.


Acked-by: Alex Shi <alex.shi@...el.com>

> 
> --
> 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@...achi.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Alex Shi <alex.shi@...el.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;
>  
> 
> 



-- 
Thanks
    Alex
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