Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942524AbcJZMqy (ORCPT ); Wed, 26 Oct 2016 08:46:54 -0400 Received: from mail-lf0-f54.google.com ([209.85.215.54]:35423 "EHLO mail-lf0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942337AbcJZMqr (ORCPT ); Wed, 26 Oct 2016 08:46:47 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH 00/14] introduce the BFQ-v0 I/O scheduler as an extra scheduler From: Paolo Valente In-Reply-To: <20161026101903.GA22361@infradead.org> Date: Wed, 26 Oct 2016 14:37:58 +0200 Cc: Jens Axboe , Tejun Heo , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org, hare@suse.de, arnd@arndb.de, bart.vanassche@sandisk.com, grant.likely@secretlab.ca, jack@suse.cz, James.Bottomley@HansenPartnership.com Message-Id: References: <1477474082-2846-1-git-send-email-paolo.valente@linaro.org> <20161026101903.GA22361@infradead.org> To: Christoph Hellwig 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 u9QCl0Rp031329 Content-Length: 1434 Lines: 43 > Il giorno 26 ott 2016, alle ore 12:19, Christoph Hellwig ha scritto: > > Just as last time: > > big NAK for introducing giant new infrastructure like a new I/O scheduler > for the legacy request structure. > I would fully agree, if there weren't important problems involved. But there are. Linux has been suffering for years from responsiveness and latency problems, related to I/O (and I/O bandwidth fairness is still just not available). Users are not happy about that. BFQ apparently solves these problems in most scenarios. Adding BFQ would not be disruptive for any use case. People could just try it if they want, and check whether things get better. IMO these problems are more important than the clear code- maintenance issue you raise. > Please direct your engergy towards blk-mq instead. Definitely. I would really like to help. To this purpose, I have already tried to stimulate discussion, as well offer and ask for help [1]. And I think that addressing these latency problems (and not only) is even more important with blk-mq. In fact, with blk-mq, they get worse, as no I/O scheduler is available yet. Thanks, Paolo [1] http://www.spinics.net/lists/linux-block/msg04555.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-block" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html