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From: Seth Jennings <spartacus06@gmail.com>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Bob Liu <bob.liu@oracle.com>, Mel Gorman <mgorman@suse.de>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Tomasz Stanislawski <t.stanislaws@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH v3 5/6] zswap: replace tree in zswap with radix tree in zbud
Date: Wed, 9 Oct 2013 12:16:17 -0500	[thread overview]
Message-ID: <20131009171617.GA21057@variantweb.net> (raw)
In-Reply-To: <20131009153022.GB5406@variantweb.net>

On Wed, Oct 09, 2013 at 10:30:22AM -0500, Seth Jennings wrote:
> In my approach, I was also looking at allowing the zbud pools to use
> HIGHMEM pages, since the handle is no longer an address.  This requires
> the pages that are being mapped to be kmapped (atomic) which will
> disable preemption.  This isn't an additional overhead since the
> map/unmap corresponds with a compress/decompress operation at the zswap
> level which uses per-cpu variables that disable preemption already.

On second though, lets not mess with the HIGHMEM page support for now.
Turns out it is tricker than I thought since the unbuddied lists are
linked through the zbud header stored in the page.  But we can still
disable preemption to allow per-cpu tracking of the current mapping and
avoid a lookup (and races) in zbud_unmap().

Seth

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  reply	other threads:[~2013-10-09 17:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-08 13:29 [PATCH v3 0/6] mm: migrate zbud pages Krzysztof Kozlowski
2013-10-08 13:29 ` [PATCH v3 1/6] zbud: use page ref counter for " Krzysztof Kozlowski
2013-10-08 20:43   ` Seth Jennings
2013-10-09  7:08     ` Krzysztof Kozlowski
2013-10-08 13:29 ` [PATCH v3 2/6] zbud: make freechunks a block local variable Krzysztof Kozlowski
2013-10-08 20:46   ` Seth Jennings
2013-10-08 13:29 ` [PATCH v3 3/6] mm: use mapcount for identifying zbud pages Krzysztof Kozlowski
2013-10-08 13:29 ` [PATCH v3 4/6] zbud: memset zbud_header to 0 during init Krzysztof Kozlowski
2013-10-08 20:48   ` Seth Jennings
2013-10-08 13:29 ` [PATCH v3 5/6] zswap: replace tree in zswap with radix tree in zbud Krzysztof Kozlowski
2013-10-09 15:30   ` Seth Jennings
2013-10-09 17:16     ` Seth Jennings [this message]
2013-10-10  7:01       ` Krzysztof Kozlowski
2013-10-08 13:29 ` [PATCH v3 6/6] mm: migrate zbud pages Krzysztof Kozlowski

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