From: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
To: Hugh Dickins <hugh@veritas.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: PageLRU can be non-atomic bit operation
Date: Mon, 23 Apr 2007 21:34:07 +0900 [thread overview]
Message-ID: <6.0.0.20.2.20070423210926.045668d0@172.19.0.2> (raw)
In-Reply-To: <Pine.LNX.4.64.0704231202390.29015@blonde.wat.veritas.com>
>No. The PG_lru flag bit is just one bit amongst many others:
>what of concurrent operations changing other bits in that same
>unsigned long e.g. trying to lock the page by setting PG_locked?
>There are some places where such micro-optimizations can be made
>(typically while first allocating the page); but in general, no.
In i386 and x86_64, btsl is used to change page flag. In this case, if btsl
without lock prefix
set PG_locked and PG_lru flag concurrently, does only one operation
succeed ?
next prev parent reply other threads:[~2007-04-23 12:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-23 10:54 Hisashi Hifumi
2007-04-23 11:16 ` Hugh Dickins
2007-04-23 12:34 ` Hisashi Hifumi [this message]
2007-04-23 13:42 ` Hugh Dickins
2007-04-24 1:54 ` Hisashi Hifumi
2007-04-24 2:29 ` KAMEZAWA Hiroyuki
2007-04-24 2:47 ` Nick Piggin
2007-04-24 8:12 ` Hisashi Hifumi
2007-04-24 10:13 ` Nick Piggin
2007-04-24 13:40 ` Hugh Dickins
2007-04-24 14:22 ` Andi Kleen
2007-04-25 8:56 ` Fernando Luis Vázquez Cao
2007-04-25 8:59 ` Andi Kleen
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