From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756326AbZDGM6q (ORCPT ); Tue, 7 Apr 2009 08:58:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751714AbZDGM6h (ORCPT ); Tue, 7 Apr 2009 08:58:37 -0400 Received: from mail-ew0-f165.google.com ([209.85.219.165]:40573 "EHLO mail-ew0-f165.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751528AbZDGM6g (ORCPT ); Tue, 7 Apr 2009 08:58:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=thuhWArdIPMfKMrL5d6yJRY9bp2SsBBFIcavqoMMqy4d2SewdvRTYy72usuNLWIKUk fa/ZuN9Ogwsh5iSyHRB5RRBc5FNqrpZAOlXf44+S9uuaYUf6ki89SbhuEvfTY/62QGxU 2O/nNt1hPo9DOf+FIiNBFW4/e4L/G5ZBTW8ks= MIME-Version: 1.0 In-Reply-To: <20090407003524.41c9b666.akpm@linux-foundation.org> References: <52041.128.227.162.217.1238684768.squirrel@webmail.cise.ufl.edu> <20090407003524.41c9b666.akpm@linux-foundation.org> Date: Tue, 7 Apr 2009 08:58:34 -0400 X-Google-Sender-Auth: d5a6744bd9e3f82a Message-ID: Subject: Re: I/O throughput problem in newer kernels From: Alin Dobra To: Andrew Morton Cc: linux-kernel@vger.kernel.org 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 Andrew (and other people interestead), I forgot to mention in the post that I used O_DIRECT for all tests (including dd tests). The CPU utilization is negligible; keep in mind that the machine has 32 cores so cpu should not be problem, or memory bandwidth for that matter. The think that puzzles me the most is the fact that the throughput does not level up, it goes down dramatically (a factor of 3 for 54 hard drives versus 20 hard drives). Alin -- Alin Dobra Assistant Professor Computer Information Science & Engineering Department University of Florida