Re: [PATCH 3/3] mm, mem-hotplug: update pcp->stat_threshold when memory hotplug occur

From: KOSAKI Motohiro
Date: Tue Apr 12 2011 - 06:34:21 EST

> > No good stat_threshold might makes performance hurt.
> Yes. That's I want it.
> My intention is that if you write down log fully, it can help much
> newbies to understand the patch in future and it would be very clear
> Andrew to merge it.
> What I want is following as.
> ==
> Currently, memory hotplug doesn't updates pcp->stat_threashold.
> Then, It ends up making the wrong stat_threshold and percpu_driftmark.
> It could make confusing zoneinfo or overhead by frequent draining.
> Even when memory is low and kswapd is awake, it can mismatch between
> the number of real free pages and vmstat NR_FREE_PAGES so that it can
> result in the livelock. Please look at aa4548403 for more.
> This patch solves the issue.
> ==

Now, wakeup_kswapd() are using zone_watermark_ok_safe(). (ie avoid to use
per-cpu stat jiffies). Then, I don't think we have livelock chance.
Am I missing something?

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