From: "Stephen C. Tweedie" <sct@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Anders Eriksson <aer-list@mailandnews.com>,
linux-kernel@vger.kernel.org, Stephen Tweedie <sct@redhat.com>
Subject: Re: sync & asyck i/o
Date: Tue, 6 Feb 2001 17:34:37 +0000 [thread overview]
Message-ID: <20010206173437.A19836@redhat.com> (raw)
In-Reply-To: <200102061424.PAA32284@hell.wii.ericsson.net> <E14Q9U2-0005gX-00@the-village.bc.nu>
In-Reply-To: <E14Q9U2-0005gX-00@the-village.bc.nu>; from alan@lxorguk.ukuu.org.uk on Tue, Feb 06, 2001 at 02:52:40PM +0000
Hi,
On Tue, Feb 06, 2001 at 02:52:40PM +0000, Alan Cox wrote:
> > According to the man page for fsync it copies in-core data to disk
> > prior to its return. Does that take async i/o to the media in account?
> > I.e. does it wait for completion of the async i/o to the disk?
>
> Undefined.
> In practice some IDE disks do write merging and small amounts of write
> caching in the drive firmware so you cannot trust it 100%.
It's worth noting that it *is* defined unambiguously in the standards:
fsync waits until all the data is hard on disk. Linux will obey that
if it possibly can: only in cases where the hardware is actively lying
about when the data has hit disk will the guarantee break down.
--Stephen
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next prev parent reply other threads:[~2001-02-06 17:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-06 14:24 sync & asyck i/o Anders Eriksson
2001-02-06 14:52 ` Alan Cox
2001-02-06 17:34 ` Stephen C. Tweedie [this message]
2001-02-06 18:00 ` Ben LaHaise
2001-02-06 18:21 ` Daniel Phillips
2001-02-06 17:51 ` Josh Myer
2001-02-06 17:56 ` Alan Cox
2001-02-06 17:54 ` David Woodhouse
2001-02-06 18:18 ` Stephen C. Tweedie
2001-02-06 19:25 ` Andre Hedrick
2001-02-06 23:21 ` Stephen C. Tweedie
2001-02-07 0:42 ` Andre Hedrick
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