On Mon, 7 Aug 2017 13:40:34 +0800 "Huang, Ying" <ying.hu...@intel.com> wrote:
> From: Huang Ying <ying.hu...@intel.com>
>
> 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?
---
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 */
_
