Re: [PATCH] mm: fix up the vmscan stat in vmstat

[Ying Han <yinghan@google.com>]

On Thu, Apr 12, 2012 at 12:05 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Thu, Apr 12, 2012 at 11:03:02AM -0700, Ying Han wrote:
>> It is always confusing on stat "pgsteal" where it counts both direct
>> reclaim as well as background reclaim. However, we have "kswapd_steal"
>> which also counts background reclaim value.
>>
>> This patch fixes it and also makes it match the existng "pgscan_" stats.
>>
>> Test:
>> pgsteal_kswapd_dma32 447623
>> pgsteal_kswapd_normal 42272677
>> pgsteal_kswapd_movable 0
>> pgsteal_direct_dma32 2801
>> pgsteal_direct_normal 44353270
>> pgsteal_direct_movable 0
>>
>> Signed-off-by: Ying Han <yinghan@google.com>
>> ---
>>  include/linux/vm_event_item.h |    5 +++--
>>  mm/vmscan.c                   |   11 ++++++++---
>>  mm/vmstat.c                   |    4 ++--
>>  3 files changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
>> index 03b90cdc..06f8e38 100644
>> --- a/include/linux/vm_event_item.h
>> +++ b/include/linux/vm_event_item.h
>> @@ -26,13 +26,14 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>>               PGFREE, PGACTIVATE, PGDEACTIVATE,
>>               PGFAULT, PGMAJFAULT,
>>               FOR_ALL_ZONES(PGREFILL),
>> -             FOR_ALL_ZONES(PGSTEAL),
>> +             FOR_ALL_ZONES(PGSTEAL_KSWAPD),
>> +             FOR_ALL_ZONES(PGSTEAL_DIRECT),
>>               FOR_ALL_ZONES(PGSCAN_KSWAPD),
>>               FOR_ALL_ZONES(PGSCAN_DIRECT),
>>  #ifdef CONFIG_NUMA
>>               PGSCAN_ZONE_RECLAIM_FAILED,
>>  #endif
>> -             PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL,
>> +             PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
>>               KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
>>               KSWAPD_SKIP_CONGESTION_WAIT,
>>               PAGEOUTRUN, ALLOCSTALL, PGROTATED,
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 33c332b..078c9fd 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1568,9 +1568,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
>>       reclaim_stat->recent_scanned[0] += nr_anon;
>>       reclaim_stat->recent_scanned[1] += nr_file;
>>
>> -     if (current_is_kswapd())
>> -             __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
>> -     __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
>> +     if (global_reclaim(sc)) {
>> +             if (current_is_kswapd())
>> +                     __count_zone_vm_events(PGSTEAL_KSWAPD, zone,
>> +                                            nr_reclaimed);
>> +             else
>> +                     __count_zone_vm_events(PGSTEAL_DIRECT, zone,
>> +                                            nr_reclaimed);
>> +     }
>
> Hey, you changed more than the changelog said!  Why no longer count
> memcg hard limit-triggered activity?

To make it consistent with "PGSCAN_*" stats, as in the commit log..
Although i could be more specific. :(

I think it is good to keep those stats to be global reclaim, and memcg
hardlimit-triggered should go to memory.vmscan_stat as you presented.

--Ying
>
> Agreed with everything else, though.

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