Re: [PATCH 2/2] Add stats to monitor soft_limit reclaim

[Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>]

2011/4/29 Ying Han <yinghan@google.com>:
> On Thu, Apr 28, 2011 at 3:37 PM, Ying Han <yinghan@google.com> wrote:
>> This patch extend the soft_limit reclaim stats to both global background
>> reclaim and global direct reclaim.
>>
>> We have a thread discussing the naming of some of the stats. Both
>> KAMEZAWA and Johannes posted the proposals. The following stats are based
>> on what i had before that thread. I will make the corresponding change on
>> the next post when we make decision.
>>
>> $cat /dev/cgroup/memory/A/memory.stat
>> kswapd_soft_steal 1053626
>> kswapd_soft_scan 1053693
>> direct_soft_steal 1481810
>> direct_soft_scan 1481996
>>
>> Signed-off-by: Ying Han <yinghan@google.com>
>> ---
>>  Documentation/cgroups/memory.txt |   10 ++++-
>>  mm/memcontrol.c                  |   68 ++++++++++++++++++++++++++++----------
>>  2 files changed, 58 insertions(+), 20 deletions(-)
>>
>> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
>> index 0c40dab..fedc107 100644
>> --- a/Documentation/cgroups/memory.txt
>> +++ b/Documentation/cgroups/memory.txt
>> @@ -387,8 +387,14 @@ pgpgout            - # of pages paged out (equivalent to # of uncharging events).
>>  swap           - # of bytes of swap usage
>>  pgfault                - # of page faults.
>>  pgmajfault     - # of major page faults.
>> -soft_steal     - # of pages reclaimed from global hierarchical reclaim
>> -soft_scan      - # of pages scanned from global hierarchical reclaim
>> +soft_kswapd_steal- # of pages reclaimed in global hierarchical reclaim from
>> +               background reclaim
>> +soft_kswapd_scan - # of pages scanned in global hierarchical reclaim from
>> +               background reclaim
>> +soft_direct_steal- # of pages reclaimed in global hierarchical reclaim from
>> +               direct reclaim
>> +soft_direct_scan- # of pages scanned in global hierarchical reclaim from
>> +               direct reclaim

Thank you for CC.

I don't have strong opinion but once we add interfaces to mainline,
it's hard to rename them. So, it's better to make a list of what name
we'll need in future.

Now, your naming has a format as [Reason]-[Who reclaim]-[What count?]
soft_kswapd_steal
soft_kswapd_scan
soft_direct_steal
soft_direct_scan

Ok, we can make a name for wmark and limit reclaim as

limit_direct_steal/scan
wmark_bg_steal/scan

Then, assume we finally do round-robin scan of memcg regardless of softlimit by
removing global LRU, what name do we have ? Hmm,

kernel_kswapd_scan/steal
kernel_direct_scan/steal

?

BTW, your changelog has different name of counters. please fix.

And I'm sorry I'll not be very active for a while.

Thanks,
-Kame

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