Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752338AbZKCXoT (ORCPT ); Tue, 3 Nov 2009 18:44:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752101AbZKCXoS (ORCPT ); Tue, 3 Nov 2009 18:44:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:28126 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751920AbZKCXoR (ORCPT ); Tue, 3 Nov 2009 18:44:17 -0500 From: Vivek Goyal To: linux-kernel@vger.kernel.org, jens.axboe@oracle.com Cc: nauman@google.com, dpshah@google.com, lizf@cn.fujitsu.com, ryov@valinux.co.jp, fernando@oss.ntt.co.jp, s-uchida@ap.jp.nec.com, taka@valinux.co.jp, guijianfeng@cn.fujitsu.com, jmoyer@redhat.com, balbir@linux.vnet.ibm.com, righi.andrea@gmail.com, m-ikeda@ds.jp.nec.com, vgoyal@redhat.com, akpm@linux-foundation.org, riel@redhat.com, kamezawa.hiroyu@jp.fujitsu.com Subject: [PATCH 15/20] blkio: Take care of preemptions across groups Date: Tue, 3 Nov 2009 18:43:52 -0500 Message-Id: <1257291837-6246-16-git-send-email-vgoyal@redhat.com> In-Reply-To: <1257291837-6246-1-git-send-email-vgoyal@redhat.com> References: <1257291837-6246-1-git-send-email-vgoyal@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2254 Lines: 70 o Additional preemption checks for groups where we travel up the hierarchy and see if one queue should preempt other or not. o Also prevents preemption across groups in some cases to provide isolation between groups. Signed-off-by: Vivek Goyal --- block/cfq-iosched.c | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 87b1799..98dbead 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2636,6 +2636,36 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, } } +static bool cfq_should_preempt_group(struct cfq_data *cfqd, + struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) +{ + struct cfq_entity *cfqe = &cfqq->entity; + struct cfq_entity *new_cfqe = &new_cfqq->entity; + + if (cfqq_to_cfqg(cfqq) != &cfqd->root_group) + cfqe = parent_entity(&cfqq->entity); + + if (cfqq_to_cfqg(new_cfqq) != &cfqd->root_group) + new_cfqe = parent_entity(&new_cfqq->entity); + + /* + * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. + */ + + if (new_cfqe->ioprio_class == IOPRIO_CLASS_RT + && cfqe->ioprio_class != IOPRIO_CLASS_RT) + return true; + /* + * Allow an BE request to pre-empt an ongoing IDLE clas timeslice. + */ + + if (new_cfqe->ioprio_class == IOPRIO_CLASS_BE + && cfqe->ioprio_class == IOPRIO_CLASS_IDLE) + return true; + + return false; +} + /* * Check if new_cfqq should preempt the currently active queue. Return 0 for * no or if we aren't sure, a 1 will cause a preempt. @@ -2666,6 +2696,9 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) return true; + if (cfqq_to_cfqg(new_cfqq) != cfqq_to_cfqg(cfqq)) + return cfq_should_preempt_group(cfqd, cfqq, new_cfqq); + /* * 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. -- 1.6.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/