Re: [PATCH 8/8] mm/vmstat: add NRSWP{IN,OUT} counters

[Baoquan He <baoquan.he@linux.dev>]

On 06/01/26 at 01:34pm, Christoph Hellwig wrote:
> Count how many swap I/Os we cause.  Due to batching this can be
> different than the currently counter number of pages written/read,
                     ~~~~~~~ current, typo?
> and tracking this information is useful to see how efficient the
> batching is.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/vm_event_item.h | 4 ++++
>  mm/page_io.c                  | 2 ++
>  mm/vmstat.c                   | 6 +++++-
>  3 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index 03fe95f5a020..2628ccda076a 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -175,6 +175,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>  		KSTACK_REST,
>  #endif
>  #endif /* CONFIG_DEBUG_STACK_USAGE */
> +#ifdef CONFIG_SWAP
> +		NRSWPIN,
> +		NRSWPOUT,
> +#endif /* CONFIG_SWAP */

Putting them together with 'SWAP_RA ... SWPOUT_ZERO' could impact the
ongoing program/script?

>  		NR_VM_EVENT_ITEMS
>  };
>  
> diff --git a/mm/page_io.c b/mm/page_io.c
> index cdac55d0a2e9..c020e8ebf966 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -695,6 +695,7 @@ void swap_write_submit(struct swap_io_ctx *ctx)
>  {
>  	if (!ctx->sio)
>  		return;
> +	count_vm_events(NRSWPOUT, 1);
>  	ctx->sis->ops->submit_write(ctx);
>  	ctx->sio = NULL;
>  	ctx->sis = NULL;
> @@ -704,6 +705,7 @@ void swap_read_submit(struct swap_io_ctx *ctx)
>  {
>  	if (!ctx->sio)
>  		return;
> +	count_vm_events(NRSWPIN, 1);
>  	ctx->sis->ops->submit_read(ctx);
>  	ctx->sio = NULL;
>  	ctx->sis = NULL;
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index f534972f517d..9559f3c95735 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1488,7 +1488,11 @@ const char * const vmstat_text[] = {
>  #if THREAD_SIZE > 65536
>  	[I(KSTACK_REST)]			= "kstack_rest",
>  #endif
> -#endif
> +#endif /* CONFIG_DEBUG_STACK_USAGE */
> +#ifdef CONFIG_SWAP
> +	[I(NRSWPIN)]				= "nrswpin",
> +	[I(NRSWPOUT)]				= "nrswpout",
> +#endif /* CONFIG_SWAP */
>  #undef I
>  #endif /* CONFIG_VM_EVENT_COUNTERS */
>  };
> -- 
> 2.53.0
>