Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753920AbdDKH3w (ORCPT ); Tue, 11 Apr 2017 03:29:52 -0400 Received: from mail-wm0-f44.google.com ([74.125.82.44]:38485 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753823AbdDKH3u (ORCPT ); Tue, 11 Apr 2017 03:29:50 -0400 Content-Type: text/plain; charset=iso-8859-1 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: bfq-mq performance comparison to cfq From: Paolo Valente In-Reply-To: <1491837330.4199.1.camel@sandisk.com> Date: Tue, 11 Apr 2017 09:29:46 +0200 Cc: "aherrmann@suse.com" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "axboe@kernel.dk" Message-Id: References: <20170410090538.GA11473@suselix.suse.de> <82BCEB46-8D05-42DA-AE06-3426895A7842@linaro.org> <1491837330.4199.1.camel@sandisk.com> To: Bart Van Assche X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v3B7VVpd009138 Content-Length: 1481 Lines: 35 > Il giorno 10 apr 2017, alle ore 17:15, Bart Van Assche ha scritto: > > On Mon, 2017-04-10 at 11:55 +0200, Paolo Valente wrote: >> That said, if you do always want maximum throughput, even at the >> expense of latency, then just switch off low-latency heuristics, i.e., >> set low_latency to 0. Depending on the device, setting slice_ilde to >> 0 may help a lot too (as well as with CFQ). If the throughput is >> still low also after forcing BFQ to an only-throughput mode, then you >> hit some bug, and I'll have a little more work to do ... > > Hello Paolo, > > Has it been considered to make applications tell the I/O scheduler > whether to optimize for latency or for throughput? It shouldn't be that > hard for window managers and shells to figure out whether or not a new > application that is being started is interactive or not. This would > require a mechanism that allows applications to provide such information > to the I/O scheduler. Wouldn't that be a better approach than the I/O > scheduler trying to guess whether or not an application is an interactive > application? > IMO that would be an (or maybe the) optimal solution, in terms of both throughput and latency. We have even developed a prototype doing what you propose, for Android. Unfortunately, I have not yet succeeded in getting support, to turn it into candidate production code, or to make a similar solution for lsb-compliant systems. Thanks, Paolo > Bart.