linux-kernel - Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys

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Message-Id: <1201110066.6341.65.camel@lappy>
Date:	Wed, 23 Jan 2008 18:41:06 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Anton Salikhmetov <salikhmetov@...il.com>, linux-mm@...ck.org,
	jakob@...hought.net, linux-kernel@...r.kernel.org,
	valdis.kletnieks@...edu, riel@...hat.com, ksm@...dk,
	staubach@...hat.com, jesper.juhl@...il.com,
	akpm@...ux-foundation.org, protasnb@...il.com, miklos@...redi.hu,
	r.e.wolff@...wizard.nl, hidave.darkstar@...il.com,
	hch@...radead.org
Subject: Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in
	sys_msync()


On Wed, 2008-01-23 at 09:05 -0800, Linus Torvalds wrote:

> So here's even a patch to get you started. Do this:
> 
> 	git revert 204ec841fbea3e5138168edbc3a76d46747cc987
> 
> and then use this appended patch on top of that as a starting point for 
> something that compiles and *possibly* works.
> 
> And no, I do *not* guarantee that this is right either! I have not tested 
> it or thought about it a lot, and S390 tends to be odd about some of these 
> things. In particular, I actually suspect that we should possibly do this 
> the same way we do
> 
> 	ptep_clear_flush_young()
> 
> except we would do "ptep_clear_flush_wrprotect()". So even though this is 
> a revert plus a simple patch to make it compile again (we've changed how 
> we do dirty bits), I think a patch like this needs testing and other 
> people like Nick and Peter to ack it.
> 
> Nick? Peter? Testing? Other comments?

It would need some addition piece to not call msync_interval() for
MS_SYNC, and remove the balance_dirty_pages_ratelimited_nr() stuff.

But yeah, this pte walker is much better. 

As for s390, I think they only differ on the dirty bit, and we should
not be touching that.

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