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

[Ying Han <yinghan@google.com>]

On Fri, Apr 29, 2011 at 3:30 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> * Ying Han <yinghan@google.com> [2011-04-28 20:28:54]:
>
>> On Thu, Apr 28, 2011 at 4:51 PM, Hiroyuki Kamezawa
>> <kamezawa.hiroyuki@gmail.com> wrote:
>> > 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
>> >
>> > ?
>>
>> Johannes has the proposal to separate out reclaims on the memcg
>> internally and externally. And then apply the format
>> [Reason]-[Who reclaim]-[What count?], also i added the 4th item .
>>
>> 1. when the memcg hits its hard_limit
>> > limit_direct_steal
>> > limit_direct_scan
>>
>> 2. when the memcg hits its wmark
>> > wmark_kswapd_steal
>> > wmark_kswapd_scan
>>
>> 3. the global direct reclaim triggers soft_limit pushback
>> > soft_direct_steal
>> > soft_direct_scan
>>
>> 4. hierarchy-triggered direct reclaim
>> > limit_hierarchy_steal
>> > limit_hierarchy_scan
>>
>> 5. the global bg reclaim triggers soft_limit pushback
>> > soft_kswapd_steal
>> > soft_kswapd_scan
>>
>
> I like these names, but these are more developer friendly than end
> user friendly.

Thank you for reviewing. One thing that I can think of to help is
better documentation. :)

--Ying

Thank you
>
> --
>        Three Cheers,
>        Balbir
>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>