Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754013AbYJNQJt (ORCPT ); Tue, 14 Oct 2008 12:09:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751796AbYJNQJj (ORCPT ); Tue, 14 Oct 2008 12:09:39 -0400 Received: from smtp-out.google.com ([216.239.33.17]:7686 "EHLO smtp-out3.google.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751046AbYJNQJi (ORCPT ); Tue, 14 Oct 2008 12:09:38 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=plW+DP5cD9noj4hwcKUt92CuOXIk1htyio4JW42Qv9epWBXgAykMTg1iHeodi2Eg6 bs+YOXiwtqlUt/GDujUsw== Message-ID: Date: Tue, 14 Oct 2008 09:09:21 -0700 From: "Grant Grundler" To: "kenneth johansson" Subject: Re: weird throughput on write to SATA disk Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <1223975694.3947.77.camel@duo> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1223925629.3947.7.camel@duo> <1223932956.3947.22.camel@duo> <1223936351.3947.41.camel@duo> <1223975694.3947.77.camel@duo> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1122 Lines: 29 On Tue, Oct 14, 2008 at 2:14 AM, kenneth johansson wrote: ... > All my numbers comes from using 1MB blocks. but I'm not using dd. > After removing the logic that actually put some data into the buffers I > do get about 105 MB/sec using O_DIRECT. Ok. Good. > I'm doing a full disk write now to get a reference plot. See http://hdperf.sourceforge.net/ and http://nathan.laredo.name/hdperf/ Simple tool to (relatively) quickly measure the perf across the disk platter. > Not using O_DIRECT should be almost identical. *should* - but there are known problems with writeback. Some of them are described nicely by Dave Chinner as "Random Thought #3": http://iou.parisc-linux.org/lsf2008/linux_storage_scalability-Dave_Chinner.odp Look for "writeback" for a summary of the discussion: http://iou.parisc-linux.org/lsf2008/SUMMARY-Storage.txt hth, grant -- 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/