From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759575Ab1FWQWE (ORCPT ); Thu, 23 Jun 2011 12:22:04 -0400 Received: from relay.parallels.com ([195.214.232.42]:58194 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754264Ab1FWQWC (ORCPT ); Thu, 23 Jun 2011 12:22:02 -0400 Subject: [PATCH] cfq-iosched: allow groups preemption for sync-noidle workloads To: Jens Axboe , , Vivek Goyal From: Konstantin Khlebnikov Date: Thu, 23 Jun 2011 20:21:59 +0400 Message-ID: <20110623162159.3192.87699.stgit@localhost6> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit v2.6.32-102-g8682e1f "blkio: Provide some isolation between groups" break fast switching between task and journal-thread for very common write-fsync workload. cfq wait idle slice at each cfqq switch, if this task is from non-root blkio cgroup. This patch move idling sync-noidle preempting check little bit upwards and update new service_tree->count check for case with two different groups. I do not quite understand what means these check for new_cfqq, but now it even works. Without patch I got 49 iops and with this patch 798, for this trivial fio script: [write-fsync] cgroup=test cgroup_weight=1000 rw=write fsync=1 size=100m runtime=10s Signed-off-by: Konstantin Khlebnikov --- block/cfq-iosched.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 3c7b537..c71533e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3318,19 +3318,19 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) return true; - if (new_cfqq->cfqg != cfqq->cfqg) - return false; - - if (cfq_slice_used(cfqq)) - return true; - /* Allow preemption only if we are idling on sync-noidle tree */ if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && - new_cfqq->service_tree->count == 2 && + new_cfqq->service_tree->count == 1+(new_cfqq->cfqg == cfqq->cfqg) && RB_EMPTY_ROOT(&cfqq->sort_list)) return true; + if (new_cfqq->cfqg != cfqq->cfqg) + return false; + + if (cfq_slice_used(cfqq)) + return true; + /* * So both queues are sync. Let the new request get disk time if * it's a metadata request and the current queue is doing regular IO.