linux-kernel - [patch 0/2] A few simplifications for softdirty memory tracker code

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Message-Id: <20140425081030.185969086@openvz.org>
Date:	Fri, 25 Apr 2014 12:10:30 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	linux-kernel@...r.kernel.org
Cc:	linux-mm@...ck.org, torvalds@...ux-foundation.org, mgorman@...e.de,
	hpa@...or.com, mingo@...nel.org, steven@...inklabs.net,
	riel@...hat.com, david.vrabel@...rix.com,
	akpm@...ux-foundation.org, peterz@...radead.org,
	xemul@...allels.com, gorcunov@...nvz.org
Subject: [patch 0/2] A few simplifications for softdirty memory tracker code

Hi, here are a few simplifications for softdirty memory tracker code, in
particular we dropped off x86-32 support since it seems noone needed it
here on x86 platform.

As Andrew requested I've rebased patches on top of current linux-next repo.

Also at first I wanted to rip off _PAGE_PSE bit which we use in swap ptes
to track dirty status of swapped pages and reuse _PAGE_BIT_SOFT_DIRTY
instead. It's still possible but requires additional shrinking of
maximal swap size and I don't know if it's acceptible or not. Currently
we have

#ifdef CONFIG_NUMA_BALANCING
/* Automatic NUMA balancing needs to be distinguishable from swap entries */
#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 2)
#else
#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
#endif

If I reuse _PAGE_BIT_SOFT_DIRTY I'll have to increase this shift up
to bit 11, which, again, I think is too much, right?

Comments are highly appreciated!

	Cyrill
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