On Tue, May 24, 2011 at 5:41 PM, KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote: >>> I'm sorry I missed this thread long time. >> >> No problem. It would be better than not review. > > thx. > > >>> In this case, I think we should call drain_all_pages(). then following >>> patch is better. >> >> Strictly speaking, this problem isn't related to drain_all_pages. >> This problem caused by lru empty but I admit it could work well if >> your patch applied. >> So yours could help, too. >> >>> However I also think your patch is valuable. because while the task is >>> sleeping in wait_iff_congested(), an another task may free some pages. >>> thus, rebalance path should try to get free pages. iow, you makes sense. >> >> Yes. >> Off-topic. >> I would like to move cond_resched below get_page_from_freelist in >> __alloc_pages_direct_reclaim. Otherwise, it is likely we can be stolen >> pages to other processes. >> One more benefit is that if it's apparently OOM path(ie, >> did_some_progress = 0), we can reduce OOM kill latency due to remove >> unnecessary cond_resched. > > I agree. Can you please mind to send a patch? I had but at that time, Andrew had a concern. I will resend it when I have a time. Let's discuss, again. > > >>> So, I'd like to propose to merge both your and my patch. >> >> Recently, there was discussion on drain_all_pages with Wu. >> He saw much overhead in 8-core system, AFAIR. >> I Cced Wu. >> >> How about checking per-cpu before calling drain_all_pages() than >> unconditional calling? >> if (per_cpu_ptr(zone->pageset, smp_processor_id()) >> Â Â drain_all_pages(); >> >> Of course, It can miss other CPU free pages. But above routine assume >> local cpu direct reclaim is successful but it failed by per-cpu. So I >> think it works. > > Can you please tell me previous discussion url or mail subject? > I mean, if it is costly and performance degression risk, we don't have to > take my idea. Yes. You could see it by https://lkml.org/lkml/2011/4/30/81. > > Thanks. > > >> >> Thanks for good suggestion and Reviewed-by, KOSAKI. > > > -- Kind regards, Minchan Kim -- 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