From mboxrd@z Thu Jan 1 00:00:00 1970 From: raghu.prabhu13@gmail.com (Raghavendra D Prabhu) Date: Sat, 14 Jan 2012 17:15:20 +0530 Subject: which local FS supports concurrent direct IO write? In-Reply-To: References: Message-ID: <20120114114520.GB4192@Xye> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Hi Zheng, * On Fri, Jan 13, 2012 at 04:41:16PM -0500, Zheng Da 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 -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 490 bytes Desc: not available Url : http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20120114/da6fb250/attachment.bin