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From: raghu.prabhu13@gmail.com (Raghavendra D Prabhu)
To: kernelnewbies@lists.kernelnewbies.org
Subject: which local FS supports concurrent direct IO write?
Date: Sat, 14 Jan 2012 17:15:20 +0530	[thread overview]
Message-ID: <20120114114520.GB4192@Xye> (raw)
In-Reply-To: <CAFLer83ddZ=D5nHFyLbUvPRo9ijpnBZvPYHL8u4RHdwuHTGMHw@mail.gmail.com>

Hi Zheng,

* On Fri, Jan 13, 2012 at 04:41:16PM -0500, Zheng Da <zhengda1936@gmail.com> wrote:
>Hello,
>
>I'm looking for a FS in Linux that supports concurrent direct IO write.
>ext4 supports concurrent direct IO read if we mount it with dioread_nolock,
>but doesn't support concurrent writes. XFS doesn't support concurrent
>direct IO at all. It locks the inode exclusive if it's direct IO. I tried
>btrfs, and it seems it doesn't support concurrent direct IO either though I
>haven't looked into its code.
>Is there a local FS that support concurrent direct IO write? It seems NFS
>supports it (
>http://kevinclosson.wordpress.com/2011/08/12/file-systems-for-a-database-choose-one-that-couples-direct-io-and-concurrent-io-whats-this-have-to-do-with-nfs-harken-back-5-2-years-to-find-out/),
>but I'm looking for local FS.
>
>Thanks,
>Da

>_______________________________________________
>Kernelnewbies mailing list
>Kernelnewbies at kernelnewbies.org
>http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

XFS locks inode exclusive only if it is an unaligned Direct 
IO, which is apparently done to prevent race conditions -- 
refer to this  http://oss.sgi.com/archives/xfs/2011-01/msg00157.html 
Also the behavior of Ext4 under dioread_nolock is supported 
by XFS by default and in a much better way. Also Ext4 is the only 
one which uses DIO_LOCKING while doing direct io.



Regards,
-- 
Raghavendra Prabhu
GPG Id : 0xD72BE977
Fingerprint: B93F EBCB 8E05 7039 CD3C A4B8 A616 DCA1 D72B E977
www: wnohang.net
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  reply	other threads:[~2012-01-14 11:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-13 21:41 which local FS supports concurrent direct IO write? Zheng Da
2012-01-14 11:45 ` Raghavendra D Prabhu [this message]
2012-01-15 20:17   ` Zheng Da
2012-01-15 21:22     ` Raghavendra D Prabhu
2012-01-15 21:48       ` Zheng Da

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