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Message-ID: <BANLkTi=+XoxHca6accmpj9B-HFrmMTtxFA@mail.gmail.com> Date: Thu, 26 May 2011 21:49:13 -0700 From: Ying Han <yinghan@...gle.com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.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>, "balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com> Subject: Re: [RFC][PATCH v3 0/10] memcg async reclaim On Thu, May 26, 2011 at 9:34 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote: > On Thu, 26 May 2011 21:33:32 -0700 > Ying Han <yinghan@...gle.com> wrote: > >> On Thu, May 26, 2011 at 7:16 PM, KAMEZAWA Hiroyuki >> <kamezawa.hiroyu@...fujitsu.com> wrote: >> > On Thu, 26 May 2011 18:49:26 -0700 >> > Ying Han <yinghan@...gle.com> wrote: >> > >> >> On Wed, May 25, 2011 at 10:10 PM, KAMEZAWA Hiroyuki >> >> <kamezawa.hiroyu@...fujitsu.com> wrote: >> >> > >> >> > It's now merge window...I just dump my patch queue to hear other's idea. >> >> > 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 numa_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. >> >> > - use SCHED_IDLE. >> >> > - removed most of heuristic codes. Now, code is very simple. >> >> > >> >> > By using SCHED_IDLE, async memory reclaim can only consume 0.3%? of cpu >> >> > 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 running >> >> > applications, SCHED_IDLE fits this work. >> >> > >> >> > If application need to stop by some I/O or event, background memory reclaim >> >> > will cull memory while the system is idle. >> >> > >> >> > Perforemce: >> >> > Running an httpd (apache) under 300M limit. And access 600MB working set >> >> > with normalized distribution access by apatch-bench. >> >> > apatch bench's concurrency was 4 and did 40960 accesses. >> >> > >> >> > Without async reclaim: >> >> > Connection Times (ms) >> >> > min mean[+/-sd] median max >> >> > Connect: 0 0 0.0 0 2 >> >> > Processing: 30 37 28.3 32 1793 >> >> > Waiting: 28 35 25.5 31 1792 >> >> > Total: 30 37 28.4 32 1793 >> >> > >> >> > Percentage of the requests served within a certain time (ms) >> >> > 50% 32 >> >> > 66% 32 >> >> > 75% 33 >> >> > 80% 34 >> >> > 90% 39 >> >> > 95% 60 >> >> > 98% 100 >> >> > 99% 133 >> >> > 100% 1793 (longest request) >> >> > >> >> > With async reclaim: >> >> > Connection Times (ms) >> >> > min mean[+/-sd] median max >> >> > Connect: 0 0 0.0 0 2 >> >> > Processing: 30 35 12.3 32 678 >> >> > Waiting: 28 34 12.0 31 658 >> >> > Total: 30 35 12.3 32 678 >> >> > >> >> > Percentage of the requests served within a certain time (ms) >> >> > 50% 32 >> >> > 66% 32 >> >> > 75% 33 >> >> > 80% 34 >> >> > 90% 39 >> >> > 95% 49 >> >> > 98% 71 >> >> > 99% 86 >> >> > 100% 678 (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. >> >> > >> >> > == without async reclaim == >> >> > 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 >> >> > >> >> > == with async reclaim == >> >> > 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 httpd. >> >> > >> >> > 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 set. >> >> >> >> 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 first. >> >> >> >> $ 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 test >> > later. >> > >> > >> > >> >> real 0m53.565s >> >> user 0m0.061s >> >> sys 0m4.814s >> >> >> >> Here is the OOM log: >> >> >> >> May 26 18:43:00 kernel: [ 963.489112] cat invoked oom-killer: >> >> gfp_mask=0xd0, order=0, oom_adj=0, oom_score_adj=0 >> >> May 26 18:43:00 kernel: [ 963.489121] Pid: 9425, comm: cat Tainted: >> >> G W 2.6.39-mcg-DEV #131 >> >> May 26 18:43:00 kernel: [ 963.489123] Call Trace: >> >> May 26 18:43:00 kernel: [ 963.489134] [<ffffffff810e3512>] >> >> dump_header+0x82/0x1af >> >> May 26 18:43:00 kernel: [ 963.489137] [<ffffffff810e33ca>] ? >> >> spin_lock+0xe/0x10 >> >> May 26 18:43:00 kernel: [ 963.489140] [<ffffffff810e33f9>] ? >> >> find_lock_task_mm+0x2d/0x67 >> >> May 26 18:43:00 kernel: [ 963.489143] [<ffffffff810e38dd>] >> >> oom_kill_process+0x50/0x27b >> >> May 26 18:43:00 kernel: [ 963.489155] [<ffffffff810e3dc6>] >> >> mem_cgroup_out_of_memory+0x9a/0xe4 >> >> May 26 18:43:00 kernel: [ 963.489160] [<ffffffff811153aa>] >> >> mem_cgroup_handle_oom+0x134/0x1fe >> >> May 26 18:43:00 kernel: [ 963.489163] [<ffffffff81114a72>] ? >> >> __mem_cgroup_insert_exceeded+0x83/0x83 >> >> May 26 18:43:00 kernel: [ 963.489176] [<ffffffff811166e9>] >> >> __mem_cgroup_try_charge.clone.3+0x368/0x43a >> >> May 26 18:43:00 kernel: [ 963.489179] [<ffffffff81117586>] >> >> mem_cgroup_cache_charge+0x95/0x123 >> >> May 26 18:43:00 kernel: [ 963.489183] [<ffffffff810e16d8>] >> >> add_to_page_cache_locked+0x42/0x114 >> >> May 26 18:43:00 kernel: [ 963.489185] [<ffffffff810e17db>] >> >> add_to_page_cache_lru+0x31/0x5f >> >> May 26 18:43:00 kernel: [ 963.489189] [<ffffffff81145636>] >> >> mpage_readpages+0xb6/0x132 >> >> May 26 18:43:00 kernel: [ 963.489194] [<ffffffff8119992f>] ? >> >> noalloc_get_block_write+0x24/0x24 >> >> May 26 18:43:00 kernel: [ 963.489197] [<ffffffff8119992f>] ? >> >> noalloc_get_block_write+0x24/0x24 >> >> May 26 18:43:00 kernel: [ 963.489201] [<ffffffff81036742>] ? >> >> __switch_to+0x160/0x212 >> >> May 26 18:43:00 kernel: [ 963.489205] [<ffffffff811978b2>] >> >> ext4_readpages+0x1d/0x1f >> >> May 26 18:43:00 kernel: [ 963.489209] [<ffffffff810e8d4b>] >> >> __do_page_cache_readahead+0x144/0x1e3 >> >> May 26 18:43:00 kernel: [ 963.489212] [<ffffffff810e8e0b>] >> >> ra_submit+0x21/0x25 >> >> May 26 18:43:00 kernel: [ 963.489215] [<ffffffff810e9075>] >> >> ondemand_readahead+0x18c/0x19f >> >> May 26 18:43:00 kernel: [ 963.489218] [<ffffffff810e9105>] >> >> page_cache_async_readahead+0x7d/0x86 >> >> May 26 18:43:00 kernel: [ 963.489221] [<ffffffff810e2b7e>] >> >> generic_file_aio_read+0x2d8/0x5fe >> >> May 26 18:43:00 kernel: [ 963.489225] [<ffffffff81119626>] >> >> do_sync_read+0xcb/0x108 >> >> May 26 18:43:00 kernel: [ 963.489230] [<ffffffff811f168a>] ? >> >> fsnotify_perm+0x66/0x72 >> >> May 26 18:43:00 kernel: [ 963.489233] [<ffffffff811f16f7>] ? >> >> security_file_permission+0x2e/0x33 >> >> May 26 18:43:00 kernel: [ 963.489236] [<ffffffff8111a0c8>] >> >> vfs_read+0xab/0x107 >> >> May 26 18:43:00 kernel: [ 963.489239] [<ffffffff8111a1e4>] sys_read+0x4a/0x6e >> >> May 26 18:43:00 kernel: [ 963.489244] [<ffffffff8140f469>] >> >> sysenter_dispatch+0x7/0x27 >> >> May 26 18:43:00 kernel: [ 963.489248] Task in /A killed as a result >> >> of limit of /A >> >> May 26 18:43:00 kernel: [ 963.489251] memory: usage 4194304kB, limit >> >> 4194304kB, failcnt 26 >> >> May 26 18:43:00 kernel: [ 963.489253] memory+swap: usage 0kB, limit >> >> 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 >> > > If you applied my patches collectly, async_control can be seen if > swap controller is configured because of BUG in patch. I noticed the BUG at the very beginning, so all my tests are having the fix. > > I could cat 20G file under 4G limit without any problem with boot option > swapaccount=0. no problem if async_control == 0 ? $ cat /dev/cgroup/memory/D/memory.async_control 1 I have the .config # CONFIG_CGROUP_MEM_RES_CTLR_SWAP is not set Not sure if that makes difference. I will test next to turn that on. --Ying > > > > 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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