Messages in this thread | | | Date | Thu, 24 Mar 2011 15:32:51 +0900 | Subject | Re: [PATCH 1/5] vmscan: remove all_unreclaimable check from direct reclaim path completely | From | Minchan Kim <> |
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On Thu, Mar 24, 2011 at 3:16 PM, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: > Hi > >> Thanks for your effort, Kosaki. >> But I still doubt this patch is good. >> >> This patch makes early oom killing in hibernation as it skip >> all_unreclaimable check. >> Normally, hibernation needs many memory so page_reclaim pressure >> would be big in small memory system. So I don't like early give up. > > Wait. When occur big pressure? hibernation reclaim pressure > (sc->nr_to_recliam) depend on physical memory size. therefore > a pressure seems to don't depend on the size.
It depends on physical memory size and /sys/power/image_size. If you want to tune image size bigger, reclaim pressure would be big.
> > >> Do you think my patch has a problem? Personally, I think it's very >> simple and clear. :) > > To be honest, I dislike following parts. It's madness on madness. > > static bool zone_reclaimable(struct zone *zone) > { > if (zone->all_unreclaimable) > return false; > > return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; > } > > > The function require a reviewer know > > o pages_scanned and all_unreclaimable are racy
Yes. That part should be written down of comment.
> o at hibernation, zone->all_unreclaimable can be false negative, > but can't be false positive.
The comment of all_unreclaimable already does explain it well, I think.
> > And, a function comment of all_unreclaimable() says > > /* > * As hibernation is going on, kswapd is freezed so that it can't mark > * the zone into all_unreclaimable. It can't handle OOM during hibernation. > * So let's check zone's unreclaimable in direct reclaim as well as kswapd. > */ > > But, now it is no longer copy of kswapd algorithm.
The comment don't say it should be a copy of kswapd.
> > If you strongly prefer this idea even if you hear above explanation, > please consider to add much and much comments. I can't say > current your patch is enough readable/reviewable.
My patch isn't a formal patch for merge but just a concept to show. If you agree the idea, of course, I will add more concrete comment when I send formal patch.
Before, I would like to get a your agreement. :) If you solve my concern(early give up in hibernation) in your patch, I don't insist on my patch, either.
Thanks for the comment, Kosaki.
> > Thanks. > > >
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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