From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756076AbcE0SYO (ORCPT ); Fri, 27 May 2016 14:24:14 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:35322 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753221AbcE0SYM (ORCPT ); Fri, 27 May 2016 14:24:12 -0400 Date: Fri, 27 May 2016 14:24:09 -0400 From: Tejun Heo To: Miao Xie Cc: Fengguang Wu , linux-kernel@vger.kernel.org Subject: Re: [BUG]Writeback Cgroup/Dirty Throttle: very small buffered write thoughput caused by writeback cgroup and dirty thottle Message-ID: <20160527182409.GR23194@mtj.duckdns.org> References: <57333E75.3080309@huawei.com> <5733D845.2030709@huawei.com> <20160512153234.GS4775@htj.duckdns.org> <57357029.5030002@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57357029.5030002@huawei.com> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Sorry about the delay. I forgot about this thread. On Fri, May 13, 2016 at 02:11:53PM +0800, Miao Xie wrote: > Better than the kernel without patch. Now the benchmark could reach > the device bandwidth after 5-8 seconds. But at the beginning, it > was still very slow, and its thoughput was only 4MB/s for ~4 > seconds, then it could go up in 1~3 seconds. I see. As this fix is needed anyways, I'll send it up. As for the ramp-up, it could be normal. There are estimators which take running avg and modulate the threshold accordingly and the starting values are conservative, so a short ramp-up time can be coming from that. Thanks. -- tejun