Re: [V4][PATCH 6/6] x86, nmi: print out NMI stats in /proc/interrupts

[Don Zickus]

On Tue, Sep 13, 2011 at 04:58:29PM -0400, Don Zickus wrote:
> This is a cheap hack to add the stats to the middle of /proc/interrupts.
> It is more of a conversation starter than anything as I am not sure
> the right letters and place to put this stuff.
> 
> The benefit of these stats is a better breakdown of which list the NMIs
> get handled in either a normal handler, unknown, or external.  It also
> list the number of unknown NMIs swallowed to help check for false
> positives or not.  Another benefit is the ability to actually see which
> NMI handlers are currently registered in the system.

I wanted to trying modifying this patch to add a /proc/nmi instead.
In there I was thinking about putting per-NMI-handler stats.  However, I
don't know how to dynamically allocate per-cpu memory (basically every
time someone registers a handler, allocate a per-cpu chunk to track its
stats).  Is this overkill?  Anyone have any ideas on how to do that?

Cheers,
Don

> 
> The output of 'cat /proc/interrupts/ will look like this:
> 
> <snip>
>  58:        275          0        864          0   PCI-MSI-edge      eth0
> NMI:       4161       4155        158       4194   Non-maskable interrupts
> SWA:          0          0          0          0   Unknown NMIs swallowed
>   0:       4161       4155        158       4194   NMI  PMI, arch_bt
> UNK:          0          0          0          0   NMI
> EXT:          0          0          0          0   NMI
> LOC:      12653      13304      13974      12926   Local timer interrupts
> SPU:          0          0          0          0   Spurious interrupts
> PMI:          6          6          5          6   Performance monitoring interrupts
> IWI:          0          0          0          0   IRQ work interrupts
> RES:       1839       1897       1821       1854   Rescheduling interrupts
> CAL:        524       2714        392        331   Function call interrupts
> TLB:        217        146        593        576   TLB shootdowns
> TRM:          0          0          0          0   Thermal event interrupts
> THR:          0          0          0          0   Threshold APIC interrupts
> MCE:          0          0          0          0   Machine check exceptions
> MCP:          1          1          1          1   Machine check polls
> ERR:          0
> MIS:          0
> 
> Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/nmi.h |    2 +
>  arch/x86/kernel/irq.c      |    2 +
>  arch/x86/kernel/nmi.c      |   47 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 51 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
> index fc74547..a4f1945 100644
> --- a/arch/x86/include/asm/nmi.h
> +++ b/arch/x86/include/asm/nmi.h
> @@ -24,6 +24,8 @@ void arch_trigger_all_cpu_backtrace(void);
>  
>  #define NMI_FLAG_FIRST	1
>  
> +void arch_show_nmi(struct seq_file *p, int prec);
> +
>  enum {
>  	NMI_LOCAL=0,
>  	NMI_UNKNOWN,
> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> index 6c0802e..44d1cac 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -16,6 +16,7 @@
>  #include <asm/idle.h>
>  #include <asm/mce.h>
>  #include <asm/hw_irq.h>
> +#include <asm/nmi.h>
>  
>  atomic_t irq_err_count;
>  
> @@ -55,6 +56,7 @@ int arch_show_interrupts(struct seq_file *p, int prec)
>  	for_each_online_cpu(j)
>  		seq_printf(p, "%10u ", irq_stats(j)->__nmi_count);
>  	seq_printf(p, "  Non-maskable interrupts\n");
> +	arch_show_nmi(p, prec);
>  #ifdef CONFIG_X86_LOCAL_APIC
>  	seq_printf(p, "%*s: ", prec, "LOC");
>  	for_each_online_cpu(j)
> diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
> index 326886c..bfcb4b8 100644
> --- a/arch/x86/kernel/nmi.c
> +++ b/arch/x86/kernel/nmi.c
> @@ -424,3 +424,50 @@ void restart_nmi(void)
>  {
>  	ignore_nmis--;
>  }
> +
> +void arch_show_nmi(struct seq_file *p, int prec)
> +{
> +	int j;
> +	struct nmiaction *action;
> +
> +	seq_printf(p, "%*s: ", prec, "SWA");
> +        for_each_online_cpu(j)
> +                seq_printf(p, "%10u ", per_cpu(nmi_stats.swallow, j));
> +        seq_printf(p, "  Unknown NMIs swallowed\n");
> +
> +	seq_printf(p, "%*s: ", prec, "  0");
> +        for_each_online_cpu(j)
> +                seq_printf(p, "%10u ", per_cpu(nmi_stats.normal, j));
> +        seq_printf(p, "  NMI");
> +	action = (nmi_to_desc(NMI_LOCAL))->head;
> +	if (action) {
> +		seq_printf(p, "\t%s", action->name);
> +		while ((action = action->next) != NULL)
> +			seq_printf(p, ", %s", action->name);
> +	}
> +	seq_putc(p, '\n');
> +
> +	seq_printf(p, "%*s: ", prec, "UNK");
> +        for_each_online_cpu(j)
> +                seq_printf(p, "%10u ", per_cpu(nmi_stats.unknown, j));
> +        seq_printf(p, "  NMI");
> +	action = (nmi_to_desc(NMI_UNKNOWN))->head;
> +	if (action) {
> +		seq_printf(p, "\t%s", action->name);
> +		while ((action = action->next) != NULL)
> +			seq_printf(p, ", %s", action->name);
> +	}
> +	seq_putc(p, '\n');
> +
> +	seq_printf(p, "%*s: ", prec, "EXT");
> +        for_each_online_cpu(j)
> +                seq_printf(p, "%10u ", per_cpu(nmi_stats.external, j));
> +        seq_printf(p, "  NMI");
> +	action = (nmi_to_desc(NMI_EXTERNAL))->head;
> +	if (action) {
> +		seq_printf(p, "\t%s", action->name);
> +		while ((action = action->next) != NULL)
> +			seq_printf(p, ", %s", action->name);
> +	}
> +	seq_putc(p, '\n');
> +}
> -- 
> 1.7.6
> 
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