Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758234AbYF1Orm (ORCPT ); Sat, 28 Jun 2008 10:47:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752859AbYF1Orf (ORCPT ); Sat, 28 Jun 2008 10:47:35 -0400 Received: from eth7959.sa.adsl.internode.on.net ([150.101.82.22]:46512 "EHLO hawking.rebel.net.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752567AbYF1Ore (ORCPT ); Sat, 28 Jun 2008 10:47:34 -0400 Message-ID: <48664F01.7060902@davidnewall.com> Date: Sun, 29 Jun 2008 00:17:29 +0930 From: David Newall User-Agent: Thunderbird 2.0.0.12 (X11/20080227) MIME-Version: 1.0 To: Martin Lucina CC: linux-kernel@vger.kernel.org, Martin Sustrik Subject: Re: Higher than expected disk write(2) latency References: <20080628121131.GA14181@nodbug.moloch.sk> In-Reply-To: <20080628121131.GA14181@nodbug.moloch.sk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 553 Lines: 12 Martin Lucina wrote: > Measurement of the write(2) time is performed using the TSC, so any > latency there is negligible. Measuring each write is lavish and bound to impact the results. To measure sustained throughput, get the time only at start and end, and divide the difference by the number of writes. -- 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/