From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 14/24] cfq-iosched: convert cfq_group_slice() to use cfqg->vfraction Date: Fri, 28 Dec 2012 12:35:36 -0800 Message-ID: <1356726946-26037-15-git-send-email-tj@kernel.org> References: <1356726946-26037-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references; bh=T2naXAfjMAsIMWnkFbtbh4zo0cu3n5cx9R2Q2/5QjqM=; b=AZ281n5qMyjAGqh/K0sNbGV8FpYdC9H59N8azQM+a3QClsGDgwkkmNb6s/FCRGnXTW QA/bhiV/moN/GgLu+KPa+pMVcjKxACBhDp4rMjvJDKWOUGIhtl6FL0Mtryg5H1U/2vMk 63Is3cYrDWQqL7gcJuhem3xi9LVYFk8fWpyKXgWBC9QN3rbeevqXe7fiKsUzhq/SEhYe RKpy1aFirulcKlPu0ulfMGWcmRqI0VIIOSez0bfCer7Skh9UbkR8IBCxWjWovAia/PBv Ls7nDGRYg8S4Aki+AhGTZbkmin/VSKM03tmWjyDiY6ImHlNVBP3vxCKzPgHMGrb/zmoe p4ow== In-Reply-To: <1356726946-26037-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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 b24acf6..ee34282 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; }; @@ -979,9 +978,7 @@ 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 @@ -1273,7 +1270,6 @@ 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 @@ -1360,7 +1356,6 @@ 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); } -- 1.8.0.2