lkml.org 
[lkml]   [2011]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH v3 0/10] memcg async reclaim
On Thu, 26 May 2011 21:33:32 -0700
Ying Han <yinghan@google.com> wrote:

> On Thu, May 26, 2011 at 7:16 PM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Thu, 26 May 2011 18:49:26 -0700
> > Ying Han <yinghan@google.com> wrote:
> >
> >> On Wed, May 25, 2011 at 10:10 PM, KAMEZAWA Hiroyuki
> >> <kamezawa.hiroyu@jp.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 could cat 20G file under 4G limit without any problem with boot option
swapaccount=0. no problem if async_control == 0 ?



Thanks,
-Kame



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-05-27 06:43    [W:0.078 / U:3.904 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site