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From: Daniel Micay <danielmicay@gmail.com>
To: Pavel Machek <pavel@ucw.cz>, Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	linux-api@vger.kernel.org, Hugh Dickins <hughd@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Jason Evans <je@fb.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Shaohua Li <shli@kernel.org>, Michal Hocko <mhocko@suse.cz>,
	yalin.wang2010@gmail.com
Subject: Re: [PATCH v2 00/13] MADV_FREE support
Date: Sat, 5 Dec 2015 10:51:58 -0500	[thread overview]
Message-ID: <5663081E.4010205@gmail.com> (raw)
In-Reply-To: <20151205111042.GA11598@amd>

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On 05/12/15 06:10 AM, Pavel Machek wrote:
> On Wed 2015-11-04 10:25:54, Minchan Kim wrote:
>> MADV_FREE is on linux-next so long time. The reason was two, I think.
>>
>> 1. MADV_FREE code on reclaim path was really mess.
> 
> Could you explain what MADV_FREE does?
> 
> Comment in code says 'free the page only when there's memory
> pressure'. So I mark my caches MADV_FREE, no memory pressure, I can
> keep using it? And if there's memory pressure, what happens? I get
> zeros? SIGSEGV?

You get zeroes. It's not designed for that use case right now. It's for
malloc implementations to use internally. There would need to be a new
feature like MADV_FREE_UNDO for it to be usable for caches and it may
make more sense for that to be a separate feature entirely, i.e. have a
different flag for marking too (not sure) since it wouldn't need to
worry about whether stuff is touched.


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      reply	other threads:[~2015-12-05 15:52 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-04  1:25 [PATCH v2 00/13] MADV_FREE support Minchan Kim
2015-11-04  1:25 ` [PATCH v2 01/13] mm: support madvise(MADV_FREE) Minchan Kim
2015-11-04  2:16   ` Sergey Senozhatsky
2015-11-04 23:39     ` Minchan Kim
2015-11-05  3:41       ` Sergey Senozhatsky
2015-11-04  2:29   ` Sergey Senozhatsky
2015-11-04 23:40     ` Minchan Kim
2015-11-04  3:41   ` Andy Lutomirski
2015-11-04  5:50     ` Daniel Micay
2015-11-04  5:53       ` Daniel Micay
2015-11-04  6:04         ` Daniel Micay
2015-11-04 18:23       ` Andy Lutomirski
2015-11-04 22:05         ` Daniel Micay
2015-11-05 18:17           ` Shaohua Li
2015-11-05 20:13             ` Daniel Micay
2015-11-05 20:14               ` Daniel Micay
2015-11-05  0:13     ` Minchan Kim
2015-11-05  0:42       ` Andy Lutomirski
2015-11-05  0:56         ` Minchan Kim
2015-11-05  1:29           ` Andy Lutomirski
2015-11-05  1:48             ` Minchan Kim
2015-11-04 20:00   ` Shaohua Li
2015-11-04 21:16     ` Daniel Micay
2015-11-04 21:29       ` Daniel Micay
2015-11-04 21:43     ` Andy Lutomirski
2015-11-05  1:33     ` Minchan Kim
2015-11-05  1:37       ` Minchan Kim
2015-12-01 22:30     ` John Stultz
2015-11-04  1:25 ` [PATCH v2 02/13] mm: define MADV_FREE for some arches Minchan Kim
2015-11-04  1:25 ` [PATCH v2 03/13] arch: uapi: asm: mman.h: Let MADV_FREE have same value for all architectures Minchan Kim
2015-11-04  1:25 ` [PATCH v2 04/13] mm: free swp_entry in madvise_free Minchan Kim
2015-11-04  1:25 ` [PATCH v2 05/13] mm: move lazily freed pages to inactive list Minchan Kim
2015-11-04  1:26 ` [PATCH v2 06/13] mm: clear PG_dirty to mark page freeable Minchan Kim
2015-11-04  1:26 ` [PATCH v2 07/13] mm: mark stable page dirty in KSM Minchan Kim
2015-11-04  1:26 ` [PATCH v2 08/13] x86: add pmd_[dirty|mkclean] for THP Minchan Kim
2015-11-04  1:26 ` [PATCH v2 09/13] sparc: " Minchan Kim
2015-11-04  1:26 ` [PATCH v2 10/13] powerpc: " Minchan Kim
2015-11-04  1:26 ` [PATCH v2 11/13] arm: add pmd_mkclean " Minchan Kim
2015-11-04  1:26 ` [PATCH v2 12/13] arm64: " Minchan Kim
2015-11-04  1:26 ` [PATCH v2 13/13] mm: don't split THP page when syscall is called Minchan Kim
2015-12-05 11:10 ` [PATCH v2 00/13] MADV_FREE support Pavel Machek
2015-12-05 15:51   ` Daniel Micay [this message]

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