On Tue, 21 Dec 2010 23:27:25 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote: > Completely disabling the oom killer for a memcg is problematic if > userspace is unable to address the condition itself, usually because > userspace is unresponsive. This scenario creates a memcg livelock: > tasks are continuously trying to allocate memory and nothing is getting > killed, so memory freeing is impossible since reclaim has failed, and > all work stalls with no remedy in sight. Userspace was buggy, surely. If userspace has elected to disable the oom-killer then it should ensure that it can cope with the ensuing result. One approach might be to run a mlockall()ed watchdog which monitors the worker tasks via shared memory. Another approach would be to run that watchdog in a different memcg, without mlockall(). There are surely plenty of other ways of doing it. > This patch adds an oom killer delay so that a memcg may be configured to > wait at least a pre-defined number of milliseconds before calling the > oom killer. If the oom condition persists for this number of > milliseconds, the oom killer will be called the next time the memory > controller attempts to charge a page (and memory.oom_control is set to > 0). This allows userspace to have a short period of time to respond to > the condition before timing out and deferring to the kernel to kill a > task. > > Admins may set the oom killer timeout using the new interface: > > # echo 60000 > memory.oom_delay > > This will defer oom killing to the kernel only after 60 seconds has > elapsed. When setting memory.oom_delay, all pending timeouts are > restarted. > eww, ick ick ick. Minutea: - changelog and docs forgot to mention that oom_delay=0 disables. - it's called oom_kill_delay in the kernel and oom_delay in userspace. - oom_delay_millisecs would be a better name for the pseudo file. - Also, ick. -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>