From: Arnd Bergmann <arnd@arndb.de>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org,
linux-kernel@vger.kernel.org,
Kyungmin Park <kyungmin.park@samsung.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>, Michal Nazarewicz <mina86@mina86.com>,
Minchan Kim <minchan@kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [RFC/PATCH 0/5] Contiguous Memory Allocator and get_user_pages()
Date: Tue, 5 Mar 2013 08:50:26 +0000 [thread overview]
Message-ID: <201303050850.26615.arnd@arndb.de> (raw)
In-Reply-To: <1362466679-17111-1-git-send-email-m.szyprowski@samsung.com>
On Tuesday 05 March 2013, Marek Szyprowski wrote:
> To solving this issue requires preventing locking of the pages, which
> are placed in CMA regions, for a long time. Our idea is to migrate
> anonymous page content before locking the page in get_user_pages(). This
> cannot be done automatically, as get_user_pages() interface is used very
> often for various operations, which usually last for a short period of
> time (like for example exec syscall). We have added a new flag
> indicating that the given get_user_space() call will grab pages for a
> long time, thus it is suitable to use the migration workaround in such
> cases.
Can you explain the tradeoff here? I would have expected that the default
should be to migrate pages out, and annotate the instances that we know
are performance critical and short-lived. That would at least appear
more reliable to me.
Arnd
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next prev parent reply other threads:[~2013-03-05 8:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-05 6:57 Marek Szyprowski
2013-03-05 6:57 ` [RFC/PATCH 1/5] mm: introduce migrate_replace_page() for migrating page to the given target Marek Szyprowski
2013-03-05 6:57 ` [RFC/PATCH 2/5] mm: get_user_pages: use static inline Marek Szyprowski
2013-03-05 6:57 ` [RFC/PATCH 3/5] mm: get_user_pages: use NON-MOVABLE pages when FOLL_DURABLE flag is set Marek Szyprowski
2013-03-06 2:02 ` Yasuaki Ishimatsu
2013-03-06 9:30 ` Lin Feng
2013-03-06 10:53 ` Lin Feng
2013-05-06 7:19 ` Tang Chen
2013-05-07 10:47 ` Marek Szyprowski
2013-05-08 5:33 ` Tang Chen
2013-03-05 6:57 ` [RFC/PATCH 4/5] mm: get_user_pages: migrate out CMA " Marek Szyprowski
2013-03-06 2:41 ` Yasuaki Ishimatsu
2013-03-05 6:57 ` [RFC/PATCH 5/5] media: vb2: use FOLL_DURABLE and __get_user_pages() to avoid CMA migration issues Marek Szyprowski
2013-03-05 8:50 ` Arnd Bergmann [this message]
2013-03-05 13:47 ` [RFC/PATCH 0/5] Contiguous Memory Allocator and get_user_pages() Marek Szyprowski
2013-03-05 19:59 ` Arnd Bergmann
2013-03-05 22:42 ` Daniel Vetter
2013-03-06 1:34 ` Yasuaki Ishimatsu
2013-03-06 8:47 ` Minchan Kim
2013-03-06 10:48 ` Marek Szyprowski
2013-03-06 11:57 ` Daniel Vetter
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