From: Mel Gorman <mgorman@suse.de>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Michal Nazarewicz <mina86@mina86.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 2/2] mm: support MIGRATE_DISCARD
Date: Wed, 5 Sep 2012 11:56:11 +0100 [thread overview]
Message-ID: <20120905105611.GI11266@suse.de> (raw)
In-Reply-To: <1346832673-12512-2-git-send-email-minchan@kernel.org>
On Wed, Sep 05, 2012 at 05:11:13PM +0900, Minchan Kim wrote:
> This patch introudes MIGRATE_DISCARD mode in migration.
> It drops *clean cache pages* instead of migration so that
> migration latency could be reduced by avoiding (memcpy + page remapping).
> It's useful for CMA because latency of migration is very important rather
> than eviction of background processes's workingset. In addition, it needs
> less free pages for migration targets so it could avoid memory reclaiming
> to get free pages, which is another factor increase latency.
>
Bah, this was released while I was reviewing the older version. I did
not read this one as closely but I see the enum problems have gone away
at least. I'd still prefer if CMA had an additional helper to discard
some pages with shrink_page_list() and migrate the remaining pages with
migrate_pages(). That would remove the need to add a MIGRATE_DISCARD
migrate mode at all.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Michal Nazarewicz <mina86@mina86.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 2/2] mm: support MIGRATE_DISCARD
Date: Wed, 5 Sep 2012 11:56:11 +0100 [thread overview]
Message-ID: <20120905105611.GI11266@suse.de> (raw)
In-Reply-To: <1346832673-12512-2-git-send-email-minchan@kernel.org>
On Wed, Sep 05, 2012 at 05:11:13PM +0900, Minchan Kim wrote:
> This patch introudes MIGRATE_DISCARD mode in migration.
> It drops *clean cache pages* instead of migration so that
> migration latency could be reduced by avoiding (memcpy + page remapping).
> It's useful for CMA because latency of migration is very important rather
> than eviction of background processes's workingset. In addition, it needs
> less free pages for migration targets so it could avoid memory reclaiming
> to get free pages, which is another factor increase latency.
>
Bah, this was released while I was reviewing the older version. I did
not read this one as closely but I see the enum problems have gone away
at least. I'd still prefer if CMA had an additional helper to discard
some pages with shrink_page_list() and migrate the remaining pages with
migrate_pages(). That would remove the need to add a MIGRATE_DISCARD
migrate mode at all.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2012-09-05 10:56 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 8:11 [PATCH 1/2] mm: change enum migrate_mode with bitwise type Minchan Kim
2012-09-05 8:11 ` Minchan Kim
2012-09-05 8:11 ` [PATCH 2/2] mm: support MIGRATE_DISCARD Minchan Kim
2012-09-05 8:11 ` Minchan Kim
2012-09-05 10:56 ` Mel Gorman [this message]
2012-09-05 10:56 ` Mel Gorman
2012-09-06 5:31 ` Minchan Kim
2012-09-06 5:31 ` Minchan Kim
2012-09-06 8:29 ` Mel Gorman
2012-09-06 8:29 ` Mel Gorman
2012-09-06 9:03 ` Mel Gorman
2012-09-06 9:03 ` Mel Gorman
2012-09-07 0:57 ` Kyungmin Park
2012-09-07 0:57 ` Kyungmin Park
2012-09-07 2:26 ` Minchan Kim
2012-09-07 2:26 ` Minchan Kim
2012-09-07 8:10 ` Mel Gorman
2012-09-07 8:10 ` Mel Gorman
2012-09-07 2:24 ` Minchan Kim
2012-09-07 2:24 ` Minchan Kim
2012-09-07 5:57 ` Kyungmin Park
2012-09-07 5:57 ` Kyungmin Park
2012-09-07 7:31 ` Kyungmin Park
2012-09-07 7:31 ` Kyungmin Park
2012-09-07 8:17 ` Minchan Kim
2012-09-07 8:17 ` Minchan Kim
2012-09-07 8:57 ` Kyungmin Park
2012-09-07 8:57 ` Kyungmin Park
2012-09-07 8:21 ` Mel Gorman
2012-09-07 8:21 ` Mel Gorman
2012-09-07 9:32 ` Mel Gorman
2012-09-07 9:32 ` Mel Gorman
2012-09-08 0:16 ` Minchan Kim
2012-09-08 0:16 ` Minchan Kim
2012-09-05 12:43 ` Michal Nazarewicz
2012-09-05 12:43 ` Michal Nazarewicz
2012-12-21 13:04 ` lihanhui
2012-12-21 13:04 ` lihanhui
2012-09-05 12:41 ` [PATCH 1/2] mm: change enum migrate_mode with bitwise type Michal Nazarewicz
2012-09-05 12:41 ` Michal Nazarewicz
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