From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 11 Oct 2000 21:59:10 +0100 (BST) From: Chris Evans Subject: Re: 2.4.0test9 vm: disappointing streaming i/o under load In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Eric Lowe Cc: linux-mm@kvack.org List-ID: On Wed, 11 Oct 2000, Eric Lowe wrote: > > Unfortunately, 2.4.0test9 exhibits poor streaming i/o performance when > > under a bit of memory pressure. [...] > Would you try setting /proc/sys/vm/page-cluster to 8 or 16 and let > me know the results? I think one _part_ of the problem is that > when the swapper isn't agressive enough, it causes too much disk > thrashing which gets in the way of normal I/O... my experience > has been that with modern disks with 512K+ cache you have to > write in 64K clusters to get optimum throughput. Raising the cluster size didn't seem to do much apart from generally slow down interactive response. Lowering it, however, seemed to make playback less jittery. I guess that's to be expected; faulting in large chunks of sequential i/o won't help much when under memory pressure because the pages will get thrown out again before they get a chance to be used. Especially with drop_behind. Rik what do you think. Cheers Chris -- 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.eu.org/Linux-MM/