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Message-Id: <20110620084123.c63d3e12.kamezawa.hiroyu@jp.fujitsu.com> Date: Mon, 20 Jun 2011 08:41:23 +0900 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> To: Ying Han <yinghan@...gle.com> Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>, "bsingharora@...il.com" <bsingharora@...il.com>, Michal Hocko <mhocko@...e.cz>, "hannes@...xchg.org" <hannes@...xchg.org>, Andrew Bresticker <abrestic@...gle.com> Subject: Re: [PATCH 3/7] memcg: add memory.scan_stat On Fri, 17 Jun 2011 15:04:18 -0700 Ying Han <yinghan@...gle.com> wrote: > On Wed, Jun 15, 2011 at 8:53 PM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@...fujitsu.com> wrote: > > From e08990dd9ada13cf236bec1ef44b207436434b8e Mon Sep 17 00:00:00 2001 > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> > > Date: Wed, 15 Jun 2011 14:11:01 +0900 > > Subject: [PATCH 3/7] memcg: add memory.scan_stat > > > > commit log of commit 0ae5e89 " memcg: count the soft_limit reclaim in..." > > says it adds scanning stats to memory.stat file. But it doesn't because > > we considered we needed to make a concensus for such new APIs. > > > > This patch is a trial to add memory.scan_stat. This shows > > - the number of scanned pages > > - the number of recleimed pages > > - the number of elaplsed time (including sleep/pause time) > > for both of direct/soft reclaim and shrinking caused by changing limit > > or force_empty. > > > > The biggest difference with oringinal Ying's one is that this file > > can be reset by some write, as > > > > # echo 0 ...../memory.scan_stat > > > > [kamezawa@...extal ~]$ cat /cgroup/memory/A/memory.scan_stat > > scanned_pages_by_limit 358470 > > freed_pages_by_limit 180795 > > elapsed_ns_by_limit 21629927 > > scanned_pages_by_system 0 > > freed_pages_by_system 0 > > elapsed_ns_by_system 0 > > scanned_pages_by_shrink 76646 > > freed_pages_by_shrink 38355 > > elappsed_ns_by_shrink 31990670 > > total_scanned_pages_by_limit 358470 > > total_freed_pages_by_limit 180795 > > total_elapsed_ns_by_hierarchical 216299275 > > total_scanned_pages_by_system 0 > > total_freed_pages_by_system 0 > > total_elapsed_ns_by_system 0 > > total_scanned_pages_by_shrink 76646 > > total_freed_pages_by_shrink 38355 > > total_elapsed_ns_by_shrink 31990670 > > > > total_xxxx is for hierarchy management. > > > > This will be useful for further memcg developments and need to be > > developped before we do some complicated rework on LRU/softlimit > > management. > > Agreed. Actually we are also looking into adding a per-memcg API for > adding visibility of > page reclaim path. It would be helpful for us to settle w/ the API first. > > I am not a fan of names, but how about > "/dev/cgroup/memory/memory.reclaim_stat" ? > Hm, ok, I have no favorite. > > > > Now, scan/free/elapsed_by_system is incomplete but future works of > > Johannes at el. will fill remaining information and then, we can > > look into problems of isolation between memcgs. > > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> > > --- > > Documentation/cgroups/memory.txt | 33 +++++++++ > > include/linux/memcontrol.h | 16 ++++ > > include/linux/swap.h | 6 - > > mm/memcontrol.c | 135 +++++++++++++++++++++++++++++++++++++-- > > mm/vmscan.c | 27 ++++++- > > 5 files changed, 199 insertions(+), 18 deletions(-) > > > > Index: mmotm-0615/Documentation/cgroups/memory.txt > > =================================================================== > > --- mmotm-0615.orig/Documentation/cgroups/memory.txt > > +++ mmotm-0615/Documentation/cgroups/memory.txt > > @@ -380,7 +380,7 @@ will be charged as a new owner of it. > > > > 5.2 stat file > > > > -memory.stat file includes following statistics > > +5.2.1 memory.stat file includes following statistics > > > > # per-memory cgroup local status > > cache - # of bytes of page cache memory. > > @@ -438,6 +438,37 @@ Note: > > file_mapped is accounted only when the memory cgroup is owner of page > > cache.) > > > > +5.2.2 memory.scan_stat > > + > > +memory.scan_stat includes statistics information for memory scanning and > > +freeing, reclaiming. The statistics shows memory scanning information since > > +memory cgroup creation and can be reset to 0 by writing 0 as > > + > > + #echo 0 > ../memory.scan_stat > > + > > +This file contains following statistics. > > + > > +scanned_pages_by_limit - # of scanned pages at hitting limit. > > +freed_pages_by_limit - # of freed pages at hitting limit. > > How those stats different from Johannes's patch? I feel we should keep > them into this API instead of memory.stat > "pgscan_direct_limit" > "pgreclaim_direct_limit" > It's unclear the unit of number from that name. And, I can't find what it means "direct_limit". Only "limit" is meaningful. > > +elapsed_ns_by_limit - nano sec of elappsed time at LRU scan at > > + hitting limit.(this includes sleep time.) > > > > + > > +scanned_pages_by_system - # of scanned pages by the kernel. > > + (Now, this value means global memory reclaim > > + caused by system memory shortage with a hint > > + of softlimit. "No soft limit" case will be > > + supported in future.) > > +freed_pages_by_system - # of freed pages by the kernel. > > The same for the following which I assume the same meaning with: > "pgscan_direct_hierarchy" > "pgreclaim_direct_hierarchy" > Doesn't make sense. What hierarchy means, here? Above 2 is for showing "amount of scanned/reclaimed memory by system's memory pressure". (But now, it just shows "softlimit" information until Johannes' work comes.) For hierarchy information, I have "total_xxxx_by_xxxx" parameter. > > +elapsed_ns_by_system - nano sec of elappsed time by kernel. > > + > > +scanned_pages_by_shrink - # of scanned pages by shrinking. > > + (i.e. changes of limit, force_empty, etc.) > > +freed_pages_by_shrink - # of freed pages by shirkining. > > So those stats are not included in the ones above? > Yes. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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