From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753410Ab1GLMPQ (ORCPT ); Tue, 12 Jul 2011 08:15:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16404 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028Ab1GLMPP (ORCPT ); Tue, 12 Jul 2011 08:15:15 -0400 Date: Tue, 12 Jul 2011 08:15:13 -0400 From: Vivek Goyal To: Shaohua Li Cc: lkml , Jens Axboe Subject: Re: [PATCH v2 0/3]CFQ: add think time check for service tree and group Message-ID: <20110712121513.GB1293@redhat.com> References: <1310434672.15392.283.camel@sli10-conroe> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1310434672.15392.283.camel@sli10-conroe> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2011 at 09:37:52AM +0800, Shaohua Li wrote: > Hi, > Currently when the last queue of a service tree/group is empty, CFQ > doesn't expire the queue. This is to allow requests from the tree/group > come soon, so tree/group doesn't miss its share. But if the think time > is big, the assumption isn't correct. idling the queue is just wasting > bandwidth. > > Originally I was hoping this can resolve Vivek's fsync issue, but it > doesn't. The fsync issue is caused by queue idling. But since think time > check only helps for think time above default queue idle time (8ms), > think time check doesn't help for the fsync issue. > > On the other hand, think time check is still helpful for queues with > think time. I had test case in follow patches show throughput > improvement without sacrifice tree/group shares. > > v1->v2: > 1. addressed some good comments from Vivek > 2. add more test to make sure the patches don't change behavior of > queues without think time. This patch series looks good to me. Thanks Shaohua. We still shall have to do something about fsync issue though in groups. Acked-by: Vivek Goyal Thanks Vivek