From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2] cfq-iosched: fix the delay of cfq_group's vdisktime under iops mode To: Hou Tao , linux-block@vger.kernel.org References: <1488975415-40417-1-git-send-email-houtao1@huawei.com> Cc: jack@suse.cz, jmoyer@redhat.com, stable@vger.kernel.org, vgoyal@redhat.com From: Jens Axboe Message-ID: Date: Wed, 8 Mar 2017 10:56:51 -0700 MIME-Version: 1.0 In-Reply-To: <1488975415-40417-1-git-send-email-houtao1@huawei.com> Content-Type: text/plain; charset=windows-1252 List-ID: On 03/08/2017 05:16 AM, Hou Tao wrote: > When adding a cfq_group into the cfq service tree, we use CFQ_IDLE_DELAY > as the delay of cfq_group's vdisktime if there have been other cfq_groups > already. > > When cfq is under iops mode, commit 9a7f38c42c2b ("cfq-iosched: Convert > from jiffies to nanoseconds") could result in a large iops delay and > lead to an abnormal io schedule delay for the added cfq_group. To fix > it, we just need to revert to the old CFQ_IDLE_DELAY value: HZ / 5 > when iops mode is enabled. > > Despite having the same value, the delay of a cfq_queue in idle class > and the delay of cfq_queue are different things, so I define two new > macros for the delay of a cfq_group under time-slice mode and IOPs mode. Added, thanks. -- Jens Axboe