Re: [resend][PATCH] mm: Restore zone->all_unreclaimable to independence word

From: KOSAKI Motohiro
Date: Thu Jan 14 2010 - 02:14:29 EST

> On Thu, 14 Jan 2010, KOSAKI Motohiro wrote:
> > commit e815af95 (change all_unreclaimable zone member to flags) chage
> > all_unreclaimable member to bit flag. but It have undesireble side
> > effect.
> > free_one_page() is one of most hot path in linux kernel and increasing
> > atomic ops in it can reduce kernel performance a bit.
> >
> > Thus, this patch revert such commit partially. at least
> > all_unreclaimable shouldn't share memory word with other zone flags.
> >
> I still think you need to quantify this; saying you don't have a large
> enough of a machine that will benefit from it isn't really a rationale for
> the lack of any data supporting your claim. We should be basing VM
> changes on data, not on speculation that there's a measurable impact
> here.
> Perhaps you could ask a colleague or another hacker to run a benchmark for
> you so that the changelog is complete?

ok, fair. although I dislike current unnecessary atomic-ops.
I'll pending this patch until get good data.


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