On 01/15/2018 03:46 PM, Michal Hocko wrote: > On Mon 15-01-18 15:30:59, Andrey Ryabinin wrote: >> >> >> On 01/12/2018 03:24 PM, Michal Hocko wrote: >>> On Fri 12-01-18 00:59:38, Andrey Ryabinin wrote: >>>> On 01/11/2018 07:29 PM, Michal Hocko wrote: >>> [...] >>>>> I do not think so. Consider that this reclaim races with other >>>>> reclaimers. Now you are reclaiming a large chunk so you might end up >>>>> reclaiming more than necessary. SWAP_CLUSTER_MAX would reduce the over >>>>> reclaim to be negligible. >>>>> >>>> >>>> I did consider this. And I think, I already explained that sort of race in previous email. >>>> Whether "Task B" is really a task in cgroup or it's actually a bunch of reclaimers, >>>> doesn't matter. That doesn't change anything. >>> >>> I would _really_ prefer two patches here. The first one removing the >>> hard coded reclaim count. That thing is just dubious at best. If you >>> _really_ think that the higher reclaim target is meaningfull then make >>> it a separate patch. I am not conviced but I will not nack it it either. >>> But it will make our life much easier if my over reclaim concern is >>> right and we will need to revert it. Conceptually those two changes are >>> independent anywa. >>> >> >> Ok, fair point. But what about livelock than? Don't you think that we should >> go back to something like in V1 patch to prevent it? > > I am not sure what do you mean by the livelock here. > Livelock is when tasks in cgroup constantly allocate reclaimable memory at high rate, and user asked to set too low unreachable limit e.g. 'echo 4096 > memory.limit_in_bytes'. We will loop indefinitely in mem_cgroup_resize_limit(), because try_to_free_mem_cgroup_pages() != 0 (as long as cgroup tasks generate new reclaimable pages fast enough). -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
