From: William Lee Irwin III <wli@holomorphy.com>
To: Kanoj Sarcar <kanojsarcar@yahoo.com>
Cc: linux-mm@kvack.org
Subject: Re: smp_rmb in mm/memory.c in 2.6.10
Date: Thu, 13 Jan 2005 12:39:54 -0800 [thread overview]
Message-ID: <20050113203954.GA6101@holomorphy.com> (raw)
In-Reply-To: <20050113202642.68138.qmail@web14325.mail.yahoo.com>
On Thu, Jan 13, 2005 at 12:26:42PM -0800, Kanoj Sarcar wrote:
> The second question is that even though truncate_count
> is declared atomic (ie probably volatile on most
> architectures), that does not make gcc guarantee
> anything in terms of ordering, right?
> Finally, does anyone really believe that a smp_rmb()
> is required in step 2? My logic is that nopage() is
> guaranteed to grab/release (spin)locks etc as part of
> its processing, and that would force the snapshots of
> truncate_count to be properly ordered.
spin_unlock() does not imply a memory barrier. e.g. on ia32 it's
not even an atomic operation.
-- wli
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next prev parent reply other threads:[~2005-01-13 20:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-13 20:26 Kanoj Sarcar
2005-01-13 20:39 ` William Lee Irwin III [this message]
2005-01-13 21:02 ` Kanoj Sarcar
2005-01-13 21:06 ` Andi Kleen
2005-01-13 21:29 ` Kanoj Sarcar
2005-01-13 21:59 ` Anton Blanchard
2005-01-13 23:22 ` Kanoj Sarcar
2005-01-14 20:37 ` Hugh Dickins
2005-01-14 21:14 ` Kanoj Sarcar
2005-01-14 21:38 ` Andrea Arcangeli
2005-01-14 22:09 ` Hugh Dickins
2005-01-14 22:34 ` Andrea Arcangeli
2005-01-14 21:25 ` Andrea Arcangeli
2005-01-14 21:32 ` Andrea Arcangeli
2005-01-14 22:22 ` Kanoj Sarcar
2005-01-14 22:47 ` Hugh Dickins
2005-01-14 22:51 ` Andrea Arcangeli
2005-01-14 23:14 ` Kanoj Sarcar
2005-01-14 23:26 ` Andrea Arcangeli
2005-01-14 22:36 ` Hugh Dickins
2005-01-14 23:01 ` Andrea Arcangeli
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