Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 24 Dec 2001 07:10:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 24 Dec 2001 07:10:06 -0500 Received: from mustard.heime.net ([194.234.65.222]:43481 "EHLO mustard.heime.net") by vger.kernel.org with ESMTP id ; Mon, 24 Dec 2001 07:09:57 -0500 Date: Mon, 24 Dec 2001 13:09:31 +0100 (CET) From: Roy Sigurd Karlsbakk To: Subject: Caching problems while reading multiple large files... Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org hi all Some time ago, I sent a message regarding what I thought had to be the RAID subsystem. I'm more convinced that this is the buffer cache messing up. scenario: read 200 large files from disk concurrently (for instance dd of=file01 of=/dev/null, dd of=file02 of=/dev/null &c.). As this is a 2x120g IDE RAID-0 config, I get pretty good throughtput, eveny though I'm reading multiple files concurrently (40-50 megs per sec). But...At the time I've read ~800 megs of data (which is the same amount as the free memory before I start), it suddenly slows down to a mere 1 meg per sec. But... If I try doing another i/o operation, even to the same block device, it works fine. Can anyone help me out here? roy -- Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA Computers are like air conditioners. They stop working when you open Windows. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/