* KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2011-04-25 18:25:29]: > > This patch is based on Ying Han's one....at its origin, but I changed too much ;) > Then, start this as new thread. > > (*) This work is not related to the topic "rewriting global LRU using memcg" > discussion, at all. This kind of hi/low watermark has been planned since > memcg was born. > > At first, per-memcg background reclaim is used for > - helping memory reclaim and avoid direct reclaim. > - set a not-hard limit of memory usage. > > For example, assume a memcg has its hard-limit as 500M bytes. > Then, set high-watermark as 400M. Here, memory usage can exceed 400M up to 500M > but memory usage will be reduced automatically to 400M as time goes by. > > This is useful when a user want to limit memory usage to 400M but don't want to > see big performance regression by hitting limit when memory usage spike happens. > > 1) == hard limit = 400M == > [root@rhel6-test hilow]# time cp ./tmpfile xxx > real 0m7.353s > user 0m0.009s > sys 0m3.280s > What do the stats look like (graphed during this period?) > 2) == hard limit 500M/ hi_watermark = 400M == > [root@rhel6-test hilow]# time cp ./tmpfile xxx > > real 0m6.421s > user 0m0.059s > sys 0m2.707s > What do the stats look like (graphed during this period?) for comparison. Does the usage extend beyond 400 very often? > Above is a brief result on VM and needs more study. But my impression is positive. > I'd like to use bigger real machine in the next time. > > Here is a short list of updates from Ying Han's one. > > 1. use workqueue and visit memcg in round robin. > 2. only allow setting hi watermark. low-watermark is automatically determined. > This is good for avoiding bad cpu usage by background reclaim. > 3. totally rewrite algorithm of shrink_mem_cgroup for round-robin. > 4. fixed get_scan_count() , this was problematic. > 5. added some statistics, which I think necessary. > 6. added documenation > > Then, the algorithm is not a cut-n-paste from kswapd. I thought kswapd should be > updated...and 'priority' in vmscan.c seems to be an enemy of memcg ;) > Thanks for looking into this. -- Three Cheers, Balbir -- 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>