Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
> On Mon, 7 Aug 2017 13:40:34 +0800 "Huang, Ying" <ying.huang@xxxxxxxxx> wrote:
>
>> From: Huang Ying <ying.huang@xxxxxxxxx>
>>
>> The statistics for total readahead pages and total readahead hits are
>> recorded and exported via the following sysfs interface.
>>
>> /sys/kernel/mm/swap/ra_hits
>> /sys/kernel/mm/swap/ra_total
>>
>> With them, the efficiency of the swap readahead could be measured, so
>> that the swap readahead algorithm and parameters could be tuned
>> accordingly.
>>
>> ...
>>
>> --- a/include/linux/vm_event_item.h
>> +++ b/include/linux/vm_event_item.h
>> @@ -106,6 +106,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>> VMACACHE_FIND_HITS,
>> VMACACHE_FULL_FLUSHES,
>> #endif
>> + SWAP_RA,
>> + SWAP_RA_HIT,
>> NR_VM_EVENT_ITEMS
>> };
>
> swap_state.o isn't even compiled if CONFIG_SWAP=n so there doesn't seem
> much point in displaying these?
Oh, Yes! Thanks for pointing this out.
Best Regards,
Huang, Ying
> --- a/include/linux/vm_event_item.h~mm-swap-add-swap-readahead-hit-statistics-fix
> +++ a/include/linux/vm_event_item.h
> @@ -106,8 +106,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
> VMACACHE_FIND_HITS,
> VMACACHE_FULL_FLUSHES,
> #endif
> +#ifdef CONFIG_SWAP
> SWAP_RA,
> SWAP_RA_HIT,
> +#endif
> NR_VM_EVENT_ITEMS
> };
>
> --- a/mm/vmstat.c~mm-swap-add-swap-readahead-hit-statistics-fix
> +++ a/mm/vmstat.c
> @@ -1098,9 +1098,10 @@ const char * const vmstat_text[] = {
> "vmacache_find_hits",
> "vmacache_full_flushes",
> #endif
> -
> +#ifdef CONFIG_SWAP
> "swap_ra",
> "swap_ra_hit",
> +#endif
> #endif /* CONFIG_VM_EVENTS_COUNTERS */
> };
> #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
> _
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