Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754020AbZASPqQ (ORCPT ); Mon, 19 Jan 2009 10:46:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751785AbZASPp7 (ORCPT ); Mon, 19 Jan 2009 10:45:59 -0500 Received: from yw-out-2324.google.com ([74.125.46.31]:25839 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751621AbZASPp6 (ORCPT ); Mon, 19 Jan 2009 10:45:58 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=CDh+6/hVIOH18KcOZfh9GlnjkQQXy4iMAIuTG+Lb+S/j2uXQ+f7D7LSLeAuPL6HRgd 0uh5LGo1e9WVHDAdhYi8lIwHl+9R6pNkgxyl3tuRsSAmUYfl2xu4o6uuuTYu9C3FXsoR cbQuo2ShLqUU81Gowjxcsz8BSvYBCqYdJ/r1k= MIME-Version: 1.0 In-Reply-To: <20090117190437.GZ30821@kernel.dk> References: <20090117004439.GA11492@Krystal> <20090117162657.GA31965@Krystal> <20090117190437.GZ30821@kernel.dk> Date: Mon, 19 Jan 2009 21:15:56 +0530 Message-ID: <807b3a220901190745w79827b41u1cc9045a2ac268e5@mail.gmail.com> Subject: Re: [RFC PATCH] block: Fix bio merge induced high I/O latency From: Nikanth K To: Jens Axboe Cc: Mathieu Desnoyers , Andrea Arcangeli , akpm@linux-foundation.org, Ingo Molnar , Linus Torvalds , linux-kernel@vger.kernel.org, ltt-dev@lists.casi.polymtl.ca Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 955 Lines: 23 On Sun, Jan 18, 2009 at 12:34 AM, Jens Axboe wrote: > > As a quick test, could you try and increase the slice_idle to eg 20ms? > Sometimes I've seen timing being slightly off, which makes us miss the > sync window for the ls (in your case) process. Then you get a mix of > async and sync IO all the time, which very much slows down the sync > process. > Do you mean to say that 'ls' could not submit another request until the previous sync request completes, but its idle window gets disabled as it takes way too long to complete during heavy load? But when there are requests in the driver, wont the idling be disabled anyway? Or did you mean to increase slice_sync? Thanks Nikanth -- 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/