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Message-ID: <20091202155027.GG31715@redhat.com>
Date: Wed, 2 Dec 2009 10:50:27 -0500
From: Vivek Goyal <vgoyal@...hat.com>
To: linux-kernel@...r.kernel.org, jens.axboe@...cle.com
Cc: nauman@...gle.com, dpshah@...gle.com, lizf@...fujitsu.com,
ryov@...inux.co.jp, fernando@....ntt.co.jp, s-uchida@...jp.nec.com,
taka@...inux.co.jp, guijianfeng@...fujitsu.com, jmoyer@...hat.com,
righi.andrea@...il.com, m-ikeda@...jp.nec.com, czoccolo@...il.com,
Alan.Brunelle@...com
Subject: Re: [PATCH 07/21] blkio: Introduce per cfq group weights and
vdisktime calculations
On Sun, Nov 29, 2009 at 09:59:14PM -0500, Vivek Goyal wrote:
> o Bring in the per cfq group weight and how vdisktime is calculated for the
> group. Also bring in the functionality of updating the min_vdisktime of
> the group service tree.
>
Reposting this patch to make use of newly introduced rb_entry_cfqg().
o Bring in the per cfq group weight and how vdisktime is calculated for the
group. Also bring in the functionality of updating the min_vdisktime of
the group service tree.
Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
block/Kconfig.iosched | 9 ++++++-
block/cfq-iosched.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 69 insertions(+), 2 deletions(-)
Index: linux10/block/cfq-iosched.c
===================================================================
--- linux10.orig/block/cfq-iosched.c 2009-12-02 10:47:17.000000000 -0500
+++ linux10/block/cfq-iosched.c 2009-12-02 10:47:53.000000000 -0500
@@ -13,6 +13,7 @@
#include <linux/rbtree.h>
#include <linux/ioprio.h>
#include <linux/blktrace_api.h>
+#include "blk-cgroup.h"
/*
* tunables
@@ -49,6 +50,7 @@ static const int cfq_hist_divisor = 4;
#define CFQ_SLICE_SCALE (5)
#define CFQ_HW_QUEUE_MIN (5)
+#define CFQ_SERVICE_SHIFT 12
#define RQ_CIC(rq) \
((struct cfq_io_context *) (rq)->elevator_private)
@@ -79,6 +81,7 @@ struct cfq_rb_root {
struct rb_node *left;
unsigned count;
u64 min_vdisktime;
+ struct rb_node *active;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
@@ -163,6 +166,7 @@ struct cfq_group {
/* group service_tree key */
u64 vdisktime;
+ unsigned int weight;
bool on_st;
/* number of cfqq currently on this group */
@@ -434,6 +438,51 @@ cfq_prio_to_slice(struct cfq_data *cfqd,
return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
}
+static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
+{
+ u64 d = delta << CFQ_SERVICE_SHIFT;
+
+ d = d * BLKIO_WEIGHT_DEFAULT;
+ do_div(d, cfqg->weight);
+ return d;
+}
+
+static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
+{
+ s64 delta = (s64)(vdisktime - min_vdisktime);
+ if (delta > 0)
+ min_vdisktime = vdisktime;
+
+ return min_vdisktime;
+}
+
+static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
+{
+ s64 delta = (s64)(vdisktime - min_vdisktime);
+ if (delta < 0)
+ min_vdisktime = vdisktime;
+
+ return min_vdisktime;
+}
+
+static void update_min_vdisktime(struct cfq_rb_root *st)
+{
+ u64 vdisktime = st->min_vdisktime;
+ struct cfq_group *cfqg;
+
+ if (st->active) {
+ cfqg = rb_entry_cfqg(st->active);
+ vdisktime = cfqg->vdisktime;
+ }
+
+ if (st->left) {
+ cfqg = rb_entry_cfqg(st->left);
+ vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
+ }
+
+ st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
+}
+
/*
* get averaged number of queues of RT/BE priority.
* average is updated, with a formula that gives more weight to higher numbers,
@@ -739,8 +788,12 @@ cfq_group_service_tree_del(struct cfq_da
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ if (st->active == &cfqg->rb_node)
+ st->active = NULL;
+
BUG_ON(cfqg->nr_cfqq < 1);
cfqg->nr_cfqq--;
+
/* If there are other cfq queues under this group, don't delete it */
if (cfqg->nr_cfqq)
return;
@@ -1659,10 +1712,14 @@ static void choose_service_tree(struct c
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ struct cfq_group *cfqg;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
- return cfq_rb_first_group(st);
+ cfqg = cfq_rb_first_group(st);
+ st->active = &cfqg->rb_node;
+ update_min_vdisktime(st);
+ return cfqg;
}
static void cfq_choose_cfqg(struct cfq_data *cfqd)
@@ -3155,6 +3212,9 @@ static void *cfq_init_queue(struct reque
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
+ /* Give preference to root group over other groups */
+ cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
+
/*
* Not strictly needed (since RB_ROOT just clears the node and we
* zeroed cfqd on alloc), but better be safe in case someone decides
Index: linux10/block/Kconfig.iosched
===================================================================
--- linux10.orig/block/Kconfig.iosched 2009-12-02 10:47:22.000000000 -0500
+++ linux10/block/Kconfig.iosched 2009-12-02 10:47:24.000000000 -0500
@@ -23,7 +23,6 @@ config IOSCHED_DEADLINE
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
- select BLK_CGROUP
default y
---help---
The CFQ I/O scheduler tries to distribute bandwidth equally
@@ -33,6 +32,14 @@ config IOSCHED_CFQ
This is the default I/O scheduler.
+config CFQ_GROUP_IOSCHED
+ bool "CFQ Group Scheduling support"
+ depends on IOSCHED_CFQ && CGROUPS
+ select BLK_CGROUP
+ default n
+ ---help---
+ Enable group IO scheduling in CFQ.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
--
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