linux-kernel - Re: [RFC][PATCH v3 1/6] mm: Don't unmap gup()ed page

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Message-Id: <200904151922.04508.nickpiggin@yahoo.com.au>
Date:	Wed, 15 Apr 2009 19:22:03 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...l.org>,
	Andrew Morton <akpm@...l.org>, Jeff Moyer <jmoyer@...hat.com>,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	Hugh Dickins <hugh@...itas.com>
Subject: Re: [RFC][PATCH v3 1/6] mm: Don't unmap gup()ed page

On Wednesday 15 April 2009 18:22:32 Nick Piggin wrote:
> On Wednesday 15 April 2009 18:05:54 KOSAKI Motohiro wrote:
> > Hi
> > 
> > > On Wednesday 15 April 2009 00:32:52 Andrea Arcangeli wrote:
> > > > On Wed, Apr 15, 2009 at 12:26:34AM +1000, Nick Piggin wrote:
> > > > > Andrea: I didn't veto that set_bit change of yours as such. I just
> > > > 
> > > > I know you didn't ;)
> > > > 
> > > > > noted there could be more atomic operations. Actually I would
> > > > > welcome more comparison between our two approaches, but they seem
> > > > 
> > > > Agree about the welcome of comparison, it'd be nice to measure it the
> > > > enterprise workloads that showed the gup_fast gain in the first place.
> > > 
> > > I think we should be able to ask IBM to run some tests, provided
> > > they still have machines available to do so. Although I don't want
> > > to waste their time so we need to have something that has got past
> > > initial code review and has a chance of being merged.
> > > 
> > > If we get that far, then I can ask them to run tests definitely.
> > 
> > Oh, it seem very charming idea.
> > Nick, I hope to help your patch's rollup. It makes good comparision, I think.
> > Is there my doable thing?
> 
> Well, I guess review and testing. There are few possibilities for
> reducing the cases where we have to de-cow (or increasing the
> cases where we can WP-on-fork), which I'd like to experiment with,
> but I don't know how much it will help...

Oh, I forgot, it needs to be updated for hugepages as well, I'd say.
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