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    SubjectRe: [PATCH -mm -v4 1/5] mm, swap: Add swap readahead hit statistics
    On Mon,  7 Aug 2017 13:40:34 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:

    > From: Huang Ying <ying.huang@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 */
    _
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      Last update: 2017-08-09 23:51    [W:5.611 / U:0.020 seconds]
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