[PATCH 16/24] io-controller: noop changes for hierarchical fair queuing

From: Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	jens.axboe-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
	nauman-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
	dpshah-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
	ryov-jCdQPDEk3idL9jVzuh4AOg@public.gmane.org
Cc: paolo.valente-rcYM44yAMweonA0d6jMUrA@public.gmane.org,
	dhaval-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org,
	fernando-gVGce1chcLdL9jVzuh4AOg@public.gmane.org,
	jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	fchecconi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
	agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
Subject: [PATCH 16/24] io-controller: noop changes for hierarchical fair queuing
Date: Fri, 24 Jul 2009 16:27:46 -0400	[thread overview]
Message-ID: <1248467274-32073-17-git-send-email-vgoyal__47826.124871108$1248467721$gmane$org@redhat.com> (raw)
In-Reply-To: <1248467274-32073-1-git-send-email-vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

This patch changes noop to use queue scheduling code from elevator layer.
One can go back to old noop by deselecting CONFIG_IOSCHED_NOOP_HIER.

Signed-off-by: Nauman Rafique <nauman-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 block/Kconfig.iosched |   11 +++++++++++
 block/noop-iosched.c  |   13 +++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index a7d0bf8..28cd500 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -25,6 +25,17 @@ config IOSCHED_NOOP
 	  that do their own scheduling and require only minimal assistance from
 	  the kernel.
 
+config IOSCHED_NOOP_HIER
+	bool "Noop Hierarchical Scheduling support"
+	depends on IOSCHED_NOOP && CGROUPS
+	select ELV_FAIR_QUEUING
+	select GROUP_IOSCHED
+	default n
+	---help---
+	  Enable hierarhical scheduling in noop. In this mode noop keeps
+	  one IO queue per cgroup instead of a global queue. Elevator
+	  fair queuing logic ensures fairness among various queues.
+
 config IOSCHED_AS
 	tristate "Anticipatory I/O scheduler"
 	default y
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index 731dbf2..5811ea2 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -82,6 +82,15 @@ static void noop_free_noop_queue(struct elevator_queue *e, void *sched_queue)
 	kfree(nq);
 }
 
+#ifdef CONFIG_IOSCHED_NOOP_HIER
+static struct elv_fs_entry noop_attrs[] = {
+	ELV_ATTR(fairness),
+	ELV_ATTR(slice_sync),
+	ELV_ATTR(group_idle),
+	__ATTR_NULL
+};
+#endif
+
 static struct elevator_type elevator_noop = {
 	.ops = {
 		.elevator_merge_req_fn		= noop_merged_requests,
@@ -92,6 +101,10 @@ static struct elevator_type elevator_noop = {
 		.elevator_alloc_sched_queue_fn	= noop_alloc_noop_queue,
 		.elevator_free_sched_queue_fn	= noop_free_noop_queue,
 	},
+#ifdef CONFIG_IOSCHED_NOOP_HIER
+	.elevator_features = ELV_IOSCHED_NEED_FQ | ELV_IOSCHED_SINGLE_IOQ,
+	.elevator_attrs = noop_attrs,
+#endif
 	.elevator_name = "noop",
 	.elevator_owner = THIS_MODULE,
 };
-- 
1.6.0.6
