From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: "Kyungmin Park" <kmpark@infradead.org>
Cc: "Linux Filesystem Mailing List" <linux-fsdevel@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: Question about synchronous write on SSD
Date: Tue, 19 Feb 2008 09:16:08 +0100 [thread overview]
Message-ID: <20080219091608.1da174c1@crazy> (raw)
In-Reply-To: <9c9fda240802182148m6fd632pa7988530c5387245@mail.gmail.com>
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Hi,
Le Tue, 19 Feb 2008 14:48:18 +0900,
"Kyungmin Park" <kmpark@infradead.org> a écrit :
> + /* Write synchronous */
> + bio->bi_rw |= (1 << BIO_RW_SYNC);
Adding BIO_RW_SYNC doesn't make generic_make_request() synchronous as
in "generic_make_request() returns only after write completion".
BIO_RW_SYNC only asks the I/O layer to unplug immediatly. But
generic_make_request() still returns before the completion of the I/O,
and the completion is notified asynchronously.
See:
http://lxr.free-electrons.com/source/include/linux/bio.h#139
Sincerly,
Thomas
--
Thomas Petazzoni, Free Electrons
Free Embedded Linux Training Materials
on http://free-electrons.com/training
(More than 1500 pages!)
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next prev parent reply other threads:[~2008-02-19 8:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-19 5:48 Question about synchronous write on SSD Kyungmin Park
2008-02-19 8:16 ` Thomas Petazzoni [this message]
2008-02-19 9:39 ` Kyungmin Park
2008-02-19 9:43 ` Jens Axboe
2008-02-19 9:55 ` Kyungmin Park
2008-02-19 10:00 ` Jens Axboe
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