From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 84EC56B004F for ; Tue, 7 Jul 2009 04:24:16 -0400 (EDT) Subject: Re: [PATCH] bump up nr_to_write in xfs_vm_writepage References: <4A4D26C5.9070606@redhat.com> From: Olaf Weber Date: Tue, 07 Jul 2009 11:07:30 +0200 In-Reply-To: <4A4D26C5.9070606@redhat.com> (Eric Sandeen's message of "Thu, 02 Jul 2009 16:29:41 -0500") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org To: Eric Sandeen Cc: xfs mailing list , Christoph Hellwig , linux-mm@kvack.org, "MASON, CHRISTOPHER" List-ID: Eric Sandeen writes: > 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? If the nr_to_write calculation really yields a value that is too small, shouldn't it be fixed elsewhere? Otherwise it might make sense to make the fudge factor tunable. > + > + /* > + * VM calculation for nr_to_write seems off. Bump it way > + * up, this gets simple streaming writes zippy again. > + */ > + wbc->nr_to_write *= 4; > + -- Olaf Weber SGI Phone: +31(0)30-6696752 Veldzigt 2b Fax: +31(0)30-6696799 Technical Lead 3454 PW de Meern Vnet: 955-7151 Storage Software The Netherlands Email: olaf@sgi.com -- 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