From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 30 Jul 2002 10:13:27 -0700 From: William Lee Irwin III Subject: Re: [RFC] start_aggressive_readahead Message-ID: <20020730171327.GC29537@holomorphy.com> References: <644994853.1028020916@[10.10.2.3]> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Description: brief message Content-Disposition: inline In-Reply-To: <644994853.1028020916@[10.10.2.3]> Sender: owner-linux-mm@kvack.org Return-Path: To: "Martin J. Bligh" Cc: Scott Kaplan , Andrew Morton , Rik van Riel , Christoph Hellwig , linux-mm@kvack.org List-ID: On Tue, Jul 30, 2002 at 09:21:57AM -0700, Martin J. Bligh wrote: > Would it not be easier to actually calculate (statistically) the > read-ahead window, rather than actually tweaking it empirically? > If we're getting misses, there could be at least two causes - I wonder where these stats should really be kept. They seem to be in the vma which probably doesn't fly too well when 20K threads are pounding on different chunks of the same thing. Each could do locally sequential reads and look random to the perspective of per-vma stats. This probably gets worse if different threads are stomping in different patterns, e.g. one sequential, one random. They also seem to lack any way to cooperate since the hints are kept per-vma. It's also probably easier to predict the behavior of a single task. Cheers, Bill -- 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/