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SubjectRe: [PATCH] IO Controller: Add per-device weight and ioprio_class handling
On Wed, May 13, 2009 at 10:00:21AM +0800, Gui Jianfeng wrote:
> Hi Vivek,
>
> This patch enables per-cgroup per-device weight and ioprio_class handling.
> A new cgroup interface "policy" is introduced. You can make use of this
> file to configure weight and ioprio_class for each device in a given cgroup.
> The original "weight" and "ioprio_class" files are still available. If you
> don't do special configuration for a particular device, "weight" and
> "ioprio_class" are used as default values in this device.
>
> You can use the following format to play with the new interface.
> #echo DEV:weight:ioprio_class > /patch/to/cgroup/policy
> weight=0 means removing the policy for DEV.
>
> Examples:
> Configure weight=300 ioprio_class=2 on /dev/hdb in this cgroup
> # echo /dev/hdb:300:2 > io.policy
> # cat io.policy
> dev weight class
> /dev/hdb 300 2
>
> Configure weight=500 ioprio_class=1 on /dev/hda in this cgroup
> # echo /dev/hda:500:1 > io.policy
> # cat io.policy
> dev weight class
> /dev/hda 500 1
> /dev/hdb 300 2
>
> Remove the policy for /dev/hda in this cgroup
> # echo /dev/hda:0:1 > io.policy
> # cat io.policy
> dev weight class
> /dev/hdb 300 2
>
> Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
> ---
> block/elevator-fq.c | 239 +++++++++++++++++++++++++++++++++++++++++++++++++-
> block/elevator-fq.h | 11 +++
> 2 files changed, 245 insertions(+), 5 deletions(-)
>
> diff --git a/block/elevator-fq.c b/block/elevator-fq.c
> index 69435ab..7c95d55 100644
> --- a/block/elevator-fq.c
> +++ b/block/elevator-fq.c
> @@ -12,6 +12,9 @@
> #include "elevator-fq.h"
> #include <linux/blktrace_api.h>
> #include <linux/biotrack.h>
> +#include <linux/seq_file.h>
> +#include <linux/genhd.h>
> +
>
> /* Values taken from cfq */
> const int elv_slice_sync = HZ / 10;
> @@ -1045,12 +1048,30 @@ struct io_group *io_lookup_io_group_current(struct request_queue *q)
> }
> EXPORT_SYMBOL(io_lookup_io_group_current);
>
> -void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog)
> +static struct policy_node *policy_search_node(const struct io_cgroup *iocg,
> + void *key);
> +
> +void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog,
> + void *key)
> {
> struct io_entity *entity = &iog->entity;
> + struct policy_node *pn;
> +
> + spin_lock_irq(&iocg->lock);
> + pn = policy_search_node(iocg, key);
> + if (pn) {
> + entity->weight = pn->weight;
> + entity->new_weight = pn->weight;
> + entity->ioprio_class = pn->ioprio_class;
> + entity->new_ioprio_class = pn->ioprio_class;
> + } else {
> + entity->weight = iocg->weight;
> + entity->new_weight = iocg->weight;
> + entity->ioprio_class = iocg->ioprio_class;
> + entity->new_ioprio_class = iocg->ioprio_class;
> + }
> + spin_unlock_irq(&iocg->lock);

Hi Gui,

It might make sense to also store the device name or device major and
minor number in io_group while creating the io group. This will help us
to display io.disk_time and io.disk_sector statistics per device instead
of aggregate.

I am attaching a patch I was playing around with to display per device
statistics instead of aggregate one. So if user has specified the per
device rule.

Thanks
Vivek


o Currently the statistics exported through cgroup are aggregate of statistics
on all devices for that cgroup. Instead of aggregate, make these per device.

o Also export another statistics io.disk_dequeue. This keeps a count of how
many times a particular group got out of race for the disk. This is a
debugging aid to keep a track how often we could create continuously
backlogged queues.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
block/elevator-fq.c | 127 +++++++++++++++++++++++++++++++++-------------------
block/elevator-fq.h | 3 +
2 files changed, 85 insertions(+), 45 deletions(-)
Index: linux14/block/elevator-fq.h
===================================================================
--- linux14.orig/block/elevator-fq.h 2009-05-13 11:40:32.000000000 -0400
+++ linux14/block/elevator-fq.h 2009-05-13 11:40:57.000000000 -0400
@@ -250,6 +250,9 @@ struct io_group {

#ifdef CONFIG_DEBUG_GROUP_IOSCHED
unsigned short iocg_id;
+ dev_t dev;
+ /* How many times this group has been removed from active tree */
+ unsigned long dequeue;
#endif
};

Index: linux14/block/elevator-fq.c
===================================================================
--- linux14.orig/block/elevator-fq.c 2009-05-13 11:40:53.000000000 -0400
+++ linux14/block/elevator-fq.c 2009-05-13 11:40:57.000000000 -0400
@@ -12,6 +12,7 @@
#include "elevator-fq.h"
#include <linux/blktrace_api.h>
#include <linux/biotrack.h>
+#include <linux/seq_file.h>

/* Values taken from cfq */
const int elv_slice_sync = HZ / 10;
@@ -758,6 +759,18 @@ int __bfq_deactivate_entity(struct io_en
BUG_ON(sd->active_entity == entity);
BUG_ON(sd->next_active == entity);

+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ struct io_group *iog = io_entity_to_iog(entity);
+ /*
+ * Keep track of how many times a group has been removed
+ * from active tree because it did not have any active
+ * backlogged ioq under it
+ */
+ if (iog)
+ iog->dequeue++;
+ }
+#endif
return ret;
}

@@ -1126,90 +1139,103 @@ STORE_FUNCTION(weight, 0, WEIGHT_MAX);
STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE);
#undef STORE_FUNCTION

-/*
- * traverse through all the io_groups associated with this cgroup and calculate
- * the aggr disk time received by all the groups on respective disks.
- */
-static u64 calculate_aggr_disk_time(struct io_cgroup *iocg)
+static int io_cgroup_disk_time_read(struct cgroup *cgroup,
+ struct cftype *cftype, struct seq_file *m)
{
+ struct io_cgroup *iocg;
struct io_group *iog;
struct hlist_node *n;
- u64 disk_time = 0;
+
+ if (!cgroup_lock_live_group(cgroup))
+ return -ENODEV;
+
+ iocg = cgroup_to_io_cgroup(cgroup);

rcu_read_lock();
+ spin_lock_irq(&iocg->lock);
hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
/*
* There might be groups which are not functional and
* waiting to be reclaimed upon cgoup deletion.
*/
- if (rcu_dereference(iog->key))
- disk_time += iog->entity.total_service;
+ if (rcu_dereference(iog->key)) {
+ seq_printf(m, "%u %u %lu\n", MAJOR(iog->dev),
+ MINOR(iog->dev),
+ iog->entity.total_service);
+ }
}
+ spin_unlock_irq(&iocg->lock);
rcu_read_unlock();

- return disk_time;
+ cgroup_unlock();
+
+ return 0;
}

-static u64 io_cgroup_disk_time_read(struct cgroup *cgroup,
- struct cftype *cftype)
+static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
+ struct cftype *cftype, struct seq_file *m)
{
struct io_cgroup *iocg;
- u64 ret;
+ struct io_group *iog;
+ struct hlist_node *n;

if (!cgroup_lock_live_group(cgroup))
return -ENODEV;

iocg = cgroup_to_io_cgroup(cgroup);
- spin_lock_irq(&iocg->lock);
- ret = jiffies_to_msecs(calculate_aggr_disk_time(iocg));
- spin_unlock_irq(&iocg->lock);
-
- cgroup_unlock();
-
- return ret;
-}
-
-/*
- * traverse through all the io_groups associated with this cgroup and calculate
- * the aggr number of sectors transferred by all the groups on respective disks.
- */
-static u64 calculate_aggr_disk_sectors(struct io_cgroup *iocg)
-{
- struct io_group *iog;
- struct hlist_node *n;
- u64 disk_sectors = 0;

rcu_read_lock();
+ spin_lock_irq(&iocg->lock);
hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
/*
* There might be groups which are not functional and
* waiting to be reclaimed upon cgoup deletion.
*/
- if (rcu_dereference(iog->key))
- disk_sectors += iog->entity.total_sector_service;
+ if (rcu_dereference(iog->key)) {
+ seq_printf(m, "%u %u %lu\n", MAJOR(iog->dev),
+ MINOR(iog->dev),
+ iog->entity.total_sector_service);
+ }
}
+ spin_unlock_irq(&iocg->lock);
rcu_read_unlock();

- return disk_sectors;
+ cgroup_unlock();
+
+ return 0;
}

-static u64 io_cgroup_disk_sectors_read(struct cgroup *cgroup,
- struct cftype *cftype)
+static int io_cgroup_disk_dequeue_read(struct cgroup *cgroup,
+ struct cftype *cftype, struct seq_file *m)
{
- struct io_cgroup *iocg;
- u64 ret;
+ struct io_cgroup *iocg = NULL;
+ struct io_group *iog = NULL;
+ struct hlist_node *n;

if (!cgroup_lock_live_group(cgroup))
return -ENODEV;

iocg = cgroup_to_io_cgroup(cgroup);
+
+ rcu_read_lock();
spin_lock_irq(&iocg->lock);
- ret = calculate_aggr_disk_sectors(iocg);
+ /* Loop through all the io groups and print statistics */
+ hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
+ /*
+ * There might be groups which are not functional and
+ * waiting to be reclaimed upon cgoup deletion.
+ */
+ if (rcu_dereference(iog->key)) {
+ seq_printf(m, "%u %u %lu\n", MAJOR(iog->dev),
+ MINOR(iog->dev), iog->dequeue);
+ }
+ }
spin_unlock_irq(&iocg->lock);
+ rcu_read_unlock();

cgroup_unlock();

- return ret;
+ return 0;
}

/**
@@ -1222,7 +1248,7 @@ static u64 io_cgroup_disk_sectors_read(s
* to the root has already an allocated group on @bfqd.
*/
struct io_group *io_group_chain_alloc(struct request_queue *q, void *key,
- struct cgroup *cgroup)
+ struct cgroup *cgroup, struct bio *bio)
{
struct io_cgroup *iocg;
struct io_group *iog, *leaf = NULL, *prev = NULL;
@@ -1250,8 +1276,13 @@ struct io_group *io_group_chain_alloc(st

io_group_init_entity(iocg, iog);
iog->my_entity = &iog->entity;
+
#ifdef CONFIG_DEBUG_GROUP_IOSCHED
iog->iocg_id = css_id(&iocg->css);
+ if (bio) {
+ struct gendisk *disk = bio->bi_bdev->bd_disk;
+ iog->dev = MKDEV(disk->major, disk->first_minor);
+ }
#endif

blk_init_request_list(&iog->rl);
@@ -1364,7 +1395,7 @@ void io_group_chain_link(struct request_
*/
struct io_group *io_find_alloc_group(struct request_queue *q,
struct cgroup *cgroup, struct elv_fq_data *efqd,
- int create)
+ int create, struct bio *bio)
{
struct io_cgroup *iocg = cgroup_to_io_cgroup(cgroup);
struct io_group *iog = NULL;
@@ -1375,7 +1406,7 @@ struct io_group *io_find_alloc_group(str
if (iog != NULL || !create)
return iog;

- iog = io_group_chain_alloc(q, key, cgroup);
+ iog = io_group_chain_alloc(q, key, cgroup, bio);
if (iog != NULL)
io_group_chain_link(q, key, cgroup, iog, efqd);

@@ -1481,7 +1512,7 @@ struct io_group *io_get_io_group(struct
goto out;
}

- iog = io_find_alloc_group(q, cgroup, efqd, create);
+ iog = io_find_alloc_group(q, cgroup, efqd, create, bio);
if (!iog) {
if (create)
iog = efqd->root_group;
@@ -1554,12 +1585,18 @@ struct cftype bfqio_files[] = {
},
{
.name = "disk_time",
- .read_u64 = io_cgroup_disk_time_read,
+ .read_seq_string = io_cgroup_disk_time_read,
},
{
.name = "disk_sectors",
- .read_u64 = io_cgroup_disk_sectors_read,
+ .read_seq_string = io_cgroup_disk_sectors_read,
},
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ .name = "disk_dequeue",
+ .read_seq_string = io_cgroup_disk_dequeue_read,
+ },
+#endif
};

int iocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)

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