From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754007AbdEIOyd (ORCPT ); Tue, 9 May 2017 10:54:33 -0400 Received: from mail-pf0-f182.google.com ([209.85.192.182]:34883 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752512AbdEIOyc (ORCPT ); Tue, 9 May 2017 10:54:32 -0400 Subject: Re: [PATCH BUGFIX] block, bfq: stress that low_latency must be off to get max throughput To: Paolo Valente References: <20170509105423.3672-1-paolo.valente@linaro.org> Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org From: Jens Axboe Message-ID: <4c59a2d1-6c09-3041-8643-cfb18941f1f9@kernel.dk> Date: Tue, 9 May 2017 08:54:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170509105423.3672-1-paolo.valente@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/09/2017 04:54 AM, Paolo Valente wrote: > The introduction of the BFQ and Kyber I/O schedulers has triggered a > new wave of I/O benchmarks. Unfortunately, comments and discussions on > these benchmarks confirm that there is still little awareness that it > is very hard to achieve, at the same time, a low latency and a high > throughput. In particular, virtually all benchmarks measure > throughput, or throughput-related figures of merit, but, for BFQ, they > use the scheduler in its default configuration. This configuration is > geared, instead, toward a low latency. This is evidently a sign that > BFQ documentation is still too unclear on this important aspect. This > commit addresses this issue by stressing how BFQ configuration must be > (easily) changed if the only goal is maximum throughput. Added, thanks. -- Jens Axboe