On Mon, 23 May 2011 15:38:31 -0700 Ying Han <yinghan@xxxxxxxxxx> wrote: > Hi Kame: > > I applied and tested the patchset on top of mmotm-2011-05-12-15-52. I > admit that I didn't look the patch closely yet, which I plan to do > next. Now i have few quick questions based on the testing result: > > Test: > 1) create a 2g memcg and enable async_control > $ mkdir /dev/cgroup/memory/A > $ echo 2g >/dev/cgroup/memory/A/memory.limit_in_bytes > $ echo 1 >/dev/cgroup/memory/A/memory.async_control > > 2) read a 20g file in the memcg > $ echo $$ >/dev/cgroup/memory/A/tasks > $ time cat /export/hdc3/dd_A/tf0 > /dev/zero > > real 4m26.677s > user 0m0.222s > sys 0m28.481s > > Here are the questions: > > 1. I monitored the "top" while the test is running. The amount of > cputime the kworkers take worries me, and the following top output > stays pretty consistent while the "cat" is running/ > memcg-async's kworker is kworker/u:x .....because of UNBOUND_WQ. Then, kworker you see is for other purpose....Hmm, from trace log, most of them are for "draining" per-cpu memcg cache. I'll prepare a patch. > Tasks: 152 total, 2 running, 150 sleeping, 0 stopped, 0 zombie > Cpu(s): 0.1%us, 1.2%sy, 0.0%ni, 87.6%id, 10.6%wa, 0.0%hi, 0.5%si, 0.0%st > Mem: 32963480k total, 2694728k used, 30268752k free, 3888k buffers > Swap: 0k total, 0k used, 0k free, 2316500k cached > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 389 root 20 0 0 0 0 R 45 0.0 1:36.24 > kworker/3:1 > 23127 root 20 0 0 0 0 S 44 0.0 0:13.44 > kworker/4:2 > 393 root 20 0 0 0 0 S 43 0.0 2:02.28 > kworker/7:1 > 32 root 20 0 0 0 0 S 42 0.0 1:54.02 > kworker/6:0 > 1230 root 20 0 0 0 0 S 42 0.0 1:22.01 > kworker/2:2 > 23130 root 20 0 0 0 0 S 31 0.0 0:04.04 > kworker/0:2 > 391 root 20 0 0 0 0 S 22 0.0 1:45.79 > kworker/5:1 > 23109 root 20 0 3104 228 180 D 10 0.0 0:08.56 cat > > I attached the tracing output of the kworkers while they are running > by doing the following: > > $ mount -t debugfs nodev /sys/kernel/debug/ > $ echo workqueue:workqueue_queue_work > /sys/kernel/debug/tracing/set_event > $ cat /sys/kernel/debug/tracing/trace_pipe > out.txt > > 2. I can not justify the cputime on the kworkers. I am looking for the > patch which we exports the time before and after workitem on memcg > basis. I recall we have that in previous post, sorry I missed that > patch somehere. > > # cat /cgroup/memory/A/memory.stat > .... > direct_elapsed_ns 0 > wmark_elapsed_ns 103566424 > direct_scanned 0 > wmark_scanned 29303 > direct_freed 0 > wmark_freed 29290 > I didn't include this for this version because you and others working on memory.stat file. I wanted to avoid to add new mess ;) I'll include it again in v3. > 3. Here is the outout of memory.stat after the test, the last one is > the memory.failcnt. As far as I remember, the failcnt is far higher > than the result i got on previous testing (per-memcg-per-kswapd > patch). This is all clean file pages which shouldn't be hard to > reclaim. > > cache 2147151872 > rss 94208 > mapped_file 0 > pgpgin 5242945 > pgpgout 4718715 > pgfault 274 > pgmajfault 0 > 1050041 > > Please let me know if the current version isn't ready for testing, and > I will wait :) > This version has tweaked to be less cpu hogging than previous one. So, hit_limit increases. I'll drop some tweakes I added in v2 for starting from a simple one. I'll post v3 in this week. But if dirty_ratio is ready, I think it should be merged 1st. But it's merge window.... 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>