From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945893Ab2LNWnt (ORCPT ); Fri, 14 Dec 2012 17:43:49 -0500 Received: from mail-ie0-f174.google.com ([209.85.223.174]:47332 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756226Ab2LNWlz (ORCPT ); Fri, 14 Dec 2012 17:41:55 -0500 From: Tejun Heo To: lizefan@huawei.com, axboe@kernel.dk, vgoyal@redhat.com Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, ctalbott@google.com, rni@google.com, Tejun Heo Subject: [PATCH 08/12] cfq-iosched: convert cfq_group_slice() to use cfqg->vfraction Date: Fri, 14 Dec 2012 14:41:21 -0800 Message-Id: <1355524885-22719-9-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1355524885-22719-1-git-send-email-tj@kernel.org> References: <1355524885-22719-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cfq_group_slice() calculates slice by taking a fraction of cfq_target_latency according to the ratio of cfqg->weight against service_tree->total_weight. This currently works only because all cfqgs are treated to be at the same level. To prepare for proper hierarchy support, convert cfq_group_slice() to base the calculation on cfqg->vfraction. As cfqg->vfraction is always a fraction of 1 and represents the fraction allocated to the cfqg with hierarchy considered, the slice can be simply calculated by multiplying cfqg->vfraction to cfq_target_latency (with fixed point shift factored in). As vfraction calculation currently treats all non-root cfqgs as children of the root cfqg, this patch doesn't introduce noticeable behavior difference. Signed-off-by: Tejun Heo --- block/cfq-iosched.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 663a0f0..fd2f4b4 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -85,7 +85,6 @@ struct cfq_rb_root { struct rb_root rb; struct rb_node *left; unsigned count; - unsigned total_weight; u64 min_vdisktime; struct cfq_ttime ttime; }; @@ -976,9 +975,7 @@ static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, static inline unsigned cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) { - struct cfq_rb_root *st = &cfqd->grp_service_tree; - - return cfqd->cfq_target_latency * cfqg->weight / st->total_weight; + return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT; } static inline unsigned @@ -1270,7 +1267,6 @@ cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) cfq_update_group_weight(cfqg); __cfq_group_service_tree_add(st, cfqg); - st->total_weight += cfqg->weight; /* * Activate @cfqg and calculate the portion of vfraction @cfqg is @@ -1356,7 +1352,6 @@ cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) } /* remove from the service tree */ - st->total_weight -= cfqg->weight; if (!RB_EMPTY_NODE(&cfqg->rb_node)) cfq_rb_erase(&cfqg->rb_node, st); } -- 1.7.11.7