From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 83FF16B0011 for ; Fri, 27 May 2011 00:33:39 -0400 (EDT) Received: from kpbe14.cbf.corp.google.com (kpbe14.cbf.corp.google.com [172.25.105.78]) by smtp-out.google.com with ESMTP id p4R4XYtd005826 for ; Thu, 26 May 2011 21:33:35 -0700 Received: from qwi2 (qwi2.prod.google.com [10.241.195.2]) by kpbe14.cbf.corp.google.com with ESMTP id p4R4XXjO011902 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Thu, 26 May 2011 21:33:33 -0700 Received: by qwi2 with SMTP id 2so1094883qwi.22 for ; Thu, 26 May 2011 21:33:33 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20110527111639.22e3e257.kamezawa.hiroyu@jp.fujitsu.com> References: <20110526141047.dc828124.kamezawa.hiroyu@jp.fujitsu.com> <20110527111639.22e3e257.kamezawa.hiroyu@jp.fujitsu.com> Date: Thu, 26 May 2011 21:33:32 -0700 Message-ID: Subject: Re: [RFC][PATCH v3 0/10] memcg async reclaim From: Ying Han Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" On Thu, May 26, 2011 at 7:16 PM, KAMEZAWA Hiroyuki wrote: > On Thu, 26 May 2011 18:49:26 -0700 > Ying Han wrote: > >> On Wed, May 25, 2011 at 10:10 PM, KAMEZAWA Hiroyuki >> wrote: >> > >> > It's now merge window...I just dump my patch queue to hear other's ide= a. >> > I wonder I should wait until dirty_ratio for memcg is queued to mmotm.= .. >> > I'll be busy with LinuxCon Japan etc...in the next week. >> > >> > This patch is onto mmotm-May-11 + some patches queued in mmotm, as num= a_stat. >> > >> > This is a patch for memcg to keep margin to the limit in background. >> > By keeping some margin to the limit in background, application can >> > avoid foreground memory reclaim at charge() and this will help latency= . >> > >> > Main changes from v2 is. >> > =A0- use SCHED_IDLE. >> > =A0- removed most of heuristic codes. Now, code is very simple. >> > >> > By using SCHED_IDLE, async memory reclaim can only consume 0.3%? of cp= u >> > if the system is truely busy but can use much CPU if the cpu is idle. >> > Because my purpose is for reducing latency without affecting other run= ning >> > applications, SCHED_IDLE fits this work. >> > >> > If application need to stop by some I/O or event, background memory re= claim >> > will cull memory while the system is idle. >> > >> > Perforemce: >> > =A0Running an httpd (apache) under 300M limit. And access 600MB workin= g set >> > =A0with normalized distribution access by apatch-bench. >> > =A0apatch bench's concurrency was 4 and did 40960 accesses. >> > >> > Without async reclaim: >> > Connection Times (ms) >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0min =A0mean[+/-sd] median =A0 max >> > Connect: =A0 =A0 =A0 =A00 =A0 =A00 =A0 0.0 =A0 =A0 =A00 =A0 =A0 =A0 2 >> > Processing: =A0 =A030 =A0 37 =A028.3 =A0 =A0 32 =A0 =A01793 >> > Waiting: =A0 =A0 =A0 28 =A0 35 =A025.5 =A0 =A0 31 =A0 =A01792 >> > Total: =A0 =A0 =A0 =A0 30 =A0 37 =A028.4 =A0 =A0 32 =A0 =A01793 >> > >> > Percentage of the requests served within a certain time (ms) >> > =A050% =A0 =A0 32 >> > =A066% =A0 =A0 32 >> > =A075% =A0 =A0 33 >> > =A080% =A0 =A0 34 >> > =A090% =A0 =A0 39 >> > =A095% =A0 =A0 60 >> > =A098% =A0 =A0100 >> > =A099% =A0 =A0133 >> > =A0100% =A0 1793 (longest request) >> > >> > With async reclaim: >> > Connection Times (ms) >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0min =A0mean[+/-sd] median =A0 max >> > Connect: =A0 =A0 =A0 =A00 =A0 =A00 =A0 0.0 =A0 =A0 =A00 =A0 =A0 =A0 2 >> > Processing: =A0 =A030 =A0 35 =A012.3 =A0 =A0 32 =A0 =A0 678 >> > Waiting: =A0 =A0 =A0 28 =A0 34 =A012.0 =A0 =A0 31 =A0 =A0 658 >> > Total: =A0 =A0 =A0 =A0 30 =A0 35 =A012.3 =A0 =A0 32 =A0 =A0 678 >> > >> > Percentage of the requests served within a certain time (ms) >> > =A050% =A0 =A0 32 >> > =A066% =A0 =A0 32 >> > =A075% =A0 =A0 33 >> > =A080% =A0 =A0 34 >> > =A090% =A0 =A0 39 >> > =A095% =A0 =A0 49 >> > =A098% =A0 =A0 71 >> > =A099% =A0 =A0 86 >> > =A0100% =A0 =A0678 (longest request) >> > >> > >> > It seems latency is stabilized by hiding memory reclaim. >> > >> > The score for memory reclaim was following. >> > See patch 10 for meaning of each member. >> > >> > =3D=3D without async reclaim =3D=3D >> > recent_scan_success_ratio 44 >> > limit_scan_pages 388463 >> > limit_freed_pages 162238 >> > limit_elapsed_ns 13852159231 >> > soft_scan_pages 0 >> > soft_freed_pages 0 >> > soft_elapsed_ns 0 >> > margin_scan_pages 0 >> > margin_freed_pages 0 >> > margin_elapsed_ns 0 >> > >> > =3D=3D with async reclaim =3D=3D >> > recent_scan_success_ratio 6 >> > limit_scan_pages 0 >> > limit_freed_pages 0 >> > limit_elapsed_ns 0 >> > soft_scan_pages 0 >> > soft_freed_pages 0 >> > soft_elapsed_ns 0 >> > margin_scan_pages 1295556 >> > margin_freed_pages 122450 >> > margin_elapsed_ns 644881521 >> > >> > >> > For this case, SCHED_IDLE workqueue can reclaim enough memory to the h= ttpd. >> > >> > I may need to dig why scan_success_ratio is far different in the both = case. >> > I guess the difference of epalsed_ns is because several threads enter >> > memory reclaim when async reclaim doesn't run. But may not... >> > >> >> >> Hmm.. I noticed a very strange behavior on a simple test w/ the patch se= t. >> >> Test: >> I created a 4g memcg and start doing cat. Then the memcg being OOM >> killed as soon as it reaches its hard_limit. We shouldn't hit OOM even >> w/o async-reclaim. >> >> Again, I will read through the patch. But like to post the test result f= irst. >> >> $ echo $$ >/dev/cgroup/memory/A/tasks >> $ cat /dev/cgroup/memory/A/memory.limit_in_bytes >> 4294967296 >> >> $ time cat /export/hdc3/dd_A/tf0 > /dev/zero >> Killed >> > > I did the same kind of test without any problem...but ok, I'll do more te= st > later. > > > >> real =A00m53.565s >> user =A00m0.061s >> sys =A0 0m4.814s >> >> Here is the OOM log: >> >> May 26 18:43:00 =A0kernel: [ =A0963.489112] cat invoked oom-killer: >> gfp_mask=3D0xd0, order=3D0, oom_adj=3D0, oom_score_adj=3D0 >> May 26 18:43:00 =A0kernel: [ =A0963.489121] Pid: 9425, comm: cat Tainted= : >> G =A0 =A0 =A0 =A0W =A0 2.6.39-mcg-DEV #131 >> May 26 18:43:00 =A0kernel: [ =A0963.489123] Call Trace: >> May 26 18:43:00 =A0kernel: [ =A0963.489134] =A0[] >> dump_header+0x82/0x1af >> May 26 18:43:00 =A0kernel: [ =A0963.489137] =A0[] ? >> spin_lock+0xe/0x10 >> May 26 18:43:00 =A0kernel: [ =A0963.489140] =A0[] ? >> find_lock_task_mm+0x2d/0x67 >> May 26 18:43:00 =A0kernel: [ =A0963.489143] =A0[] >> oom_kill_process+0x50/0x27b >> May 26 18:43:00 =A0kernel: [ =A0963.489155] =A0[] >> mem_cgroup_out_of_memory+0x9a/0xe4 >> May 26 18:43:00 =A0kernel: [ =A0963.489160] =A0[] >> mem_cgroup_handle_oom+0x134/0x1fe >> May 26 18:43:00 =A0kernel: [ =A0963.489163] =A0[] ? >> __mem_cgroup_insert_exceeded+0x83/0x83 >> May 26 18:43:00 =A0kernel: [ =A0963.489176] =A0[] >> __mem_cgroup_try_charge.clone.3+0x368/0x43a >> May 26 18:43:00 =A0kernel: [ =A0963.489179] =A0[] >> mem_cgroup_cache_charge+0x95/0x123 >> May 26 18:43:00 =A0kernel: [ =A0963.489183] =A0[] >> add_to_page_cache_locked+0x42/0x114 >> May 26 18:43:00 =A0kernel: [ =A0963.489185] =A0[] >> add_to_page_cache_lru+0x31/0x5f >> May 26 18:43:00 =A0kernel: [ =A0963.489189] =A0[] >> mpage_readpages+0xb6/0x132 >> May 26 18:43:00 =A0kernel: [ =A0963.489194] =A0[] ? >> noalloc_get_block_write+0x24/0x24 >> May 26 18:43:00 =A0kernel: [ =A0963.489197] =A0[] ? >> noalloc_get_block_write+0x24/0x24 >> May 26 18:43:00 =A0kernel: [ =A0963.489201] =A0[] ? >> __switch_to+0x160/0x212 >> May 26 18:43:00 =A0kernel: [ =A0963.489205] =A0[] >> ext4_readpages+0x1d/0x1f >> May 26 18:43:00 =A0kernel: [ =A0963.489209] =A0[] >> __do_page_cache_readahead+0x144/0x1e3 >> May 26 18:43:00 =A0kernel: [ =A0963.489212] =A0[] >> ra_submit+0x21/0x25 >> May 26 18:43:00 =A0kernel: [ =A0963.489215] =A0[] >> ondemand_readahead+0x18c/0x19f >> May 26 18:43:00 =A0kernel: [ =A0963.489218] =A0[] >> page_cache_async_readahead+0x7d/0x86 >> May 26 18:43:00 =A0kernel: [ =A0963.489221] =A0[] >> generic_file_aio_read+0x2d8/0x5fe >> May 26 18:43:00 =A0kernel: [ =A0963.489225] =A0[] >> do_sync_read+0xcb/0x108 >> May 26 18:43:00 =A0kernel: [ =A0963.489230] =A0[] ? >> fsnotify_perm+0x66/0x72 >> May 26 18:43:00 =A0kernel: [ =A0963.489233] =A0[] ? >> security_file_permission+0x2e/0x33 >> May 26 18:43:00 =A0kernel: [ =A0963.489236] =A0[] >> vfs_read+0xab/0x107 >> May 26 18:43:00 =A0kernel: [ =A0963.489239] =A0[] sys_= read+0x4a/0x6e >> May 26 18:43:00 =A0kernel: [ =A0963.489244] =A0[] >> sysenter_dispatch+0x7/0x27 >> May 26 18:43:00 =A0kernel: [ =A0963.489248] Task in /A killed as a resul= t >> of limit of /A >> May 26 18:43:00 =A0kernel: [ =A0963.489251] memory: usage 4194304kB, lim= it >> 4194304kB, failcnt 26 >> May 26 18:43:00 =A0kernel: [ =A0963.489253] memory+swap: usage 0kB, limi= t >> 9007199254740991kB, failcnt 0 >> > > Hmm, why memory+swap usage 0kb here... > > In this set, I used mem_cgroup_margin() rather than res_counter_margin(). > Hmm, do you disable swap accounting ? If so, I may miss some. Yes, I disabled the swap accounting in .config: # CONFIG_CGROUP_MEM_RES_CTLR_SWAP is not set Here is how i reproduce it: $ mkdir /dev/cgroup/memory/D $ echo 4g >/dev/cgroup/memory/D/memory.limit_in_bytes $ cat /dev/cgroup/memory/D/memory.limit_in_bytes 4294967296 $ cat /dev/cgroup/memory/D/memory. memory.async_control memory.max_usage_in_bytes memory.soft_limit_in_bytes memory.use_hierarchy memory.failcnt memory.move_charge_at_immigrate memory.stat memory.force_empty memory.oom_control memory.swappiness memory.limit_in_bytes memory.reclaim_stat memory.usage_in_bytes $ cat /dev/cgroup/memory/D/memory.async_control 0 $ echo 1 >/dev/cgroup/memory/D/memory.async_control $ cat /dev/cgroup/memory/D/memory.async_control 1 $ echo $$ >/dev/cgroup/memory/D/tasks $ cat /proc/4358/cgroup 3:memory:/D $ time cat /export/hdc3/dd_A/tf0 > /dev/zero Killed --Ying > > Thanks, > -Kame > > > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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