On Thu, 26 May 2011 18:49:26 -0700 Ying Han <yinghan@xxxxxxxxxx> wrote: > On Wed, May 25, 2011 at 10:10 PM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@xxxxxxxxxxxxxx> 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. > > Â- use SCHED_IDLE. > > Â- 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: > > ÂRunning an httpd (apache) under 300M limit. And access 600MB working set > > Âwith normalized distribution access by apatch-bench. > > Âapatch bench's concurrency was 4 and did 40960 accesses. > > > > Without async reclaim: > > Connection Times (ms) > >       Âmin Âmean[+/-sd] median  max > > Connect:    Â0  Â0  0.0   Â0    2 > > Processing:  Â30  37 Â28.3   32  Â1793 > > Waiting:    28  35 Â25.5   31  Â1792 > > Total:     30  37 Â28.4   32  Â1793 > > > > Percentage of the requests served within a certain time (ms) > > Â50%   32 > > Â66%   32 > > Â75%   33 > > Â80%   34 > > Â90%   39 > > Â95%   60 > > Â98%  Â100 > > Â99%  Â133 > > Â100%  1793 (longest request) > > > > With async reclaim: > > Connection Times (ms) > >       Âmin Âmean[+/-sd] median  max > > Connect:    Â0  Â0  0.0   Â0    2 > > Processing:  Â30  35 Â12.3   32   678 > > Waiting:    28  34 Â12.0   31   658 > > Total:     30  35 Â12.3   32   678 > > > > Percentage of the requests served within a certain time (ms) > > Â50%   32 > > Â66%   32 > > Â75%   33 > > Â80%   34 > > Â90%   39 > > Â95%   49 > > Â98%   71 > > Â99%   86 > > Â100%  Â678 (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 > > real 0m53.565s > user 0m0.061s > sys 0m4.814s > Hmm, what I see is == root@bluextal kamezawa]# ls -l test/1G -rw-rw-r--. 1 kamezawa kamezawa 1053261824 May 13 13:58 test/1G [root@bluextal kamezawa]# mkdir /cgroup/memory/A [root@bluextal kamezawa]# echo 0 > /cgroup/memory/A/tasks [root@bluextal kamezawa]# echo 300M > /cgroup/memory/A/memory.limit_in_bytes [root@bluextal kamezawa]# echo 1 > /cgroup/memory/A/memory.async_control [root@bluextal kamezawa]# cat test/1G > /dev/null [root@bluextal kamezawa]# cat /cgroup/memory/A/memory.reclaim_stat recent_scan_success_ratio 83 limit_scan_pages 82 limit_freed_pages 49 limit_elapsed_ns 242507 soft_scan_pages 0 soft_freed_pages 0 soft_elapsed_ns 0 margin_scan_pages 218630 margin_freed_pages 181598 margin_elapsed_ns 117466604 [root@bluextal kamezawa]# == I'll turn off swapaccount and try again. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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@xxxxxxxxx";> email@xxxxxxxxx </a>