From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 345EC6B004F for ; Thu, 2 Jul 2009 17:22:28 -0400 (EDT) Message-ID: <4A4D26C5.9070606@redhat.com> Date: Thu, 02 Jul 2009 16:29:41 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: [PATCH] bump up nr_to_write in xfs_vm_writepage Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: xfs mailing list Cc: linux-mm@kvack.org, Christoph Hellwig , "MASON,CHRISTOPHER" List-ID: Talking w/ someone who had a raid6 of 15 drives on an areca controller, he wondered why he could only get 300MB/s or so out of a streaming buffered write to xfs like so: dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920 10737418240 bytes (11 GB) copied, 34.294 s, 313 MB/s when the same write directly to the device was going closer to 700MB/s... With the following change things get moving again for xfs: dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920 10737418240 bytes (11 GB) copied, 16.2938 s, 659 MB/s Chris had sent out something similar at Christoph's suggestion, and Christoph reminded me of it, and I tested it a variant of it, and it seems to help shockingly well. Feels like a bandaid though; thoughts? Other tests to do? Thanks, -Eric Signed-off-by: Christoph Hellwig Signed-off-by: Eric Sandeen Cc: Chris Mason --- Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.c =================================================================== --- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.c +++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.c @@ -1268,6 +1268,13 @@ xfs_vm_writepage( if (!page_has_buffers(page)) create_empty_buffers(page, 1 << inode->i_blkbits, 0); + + /* + * VM calculation for nr_to_write seems off. Bump it way + * up, this gets simple streaming writes zippy again. + */ + wbc->nr_to_write *= 4; + /* * Convert delayed allocate, unwritten or unmapped space * to real space and flush out to disk. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org