[dm-devel] Re: [PATCH] IO Controller: Add per-device weight and ioprio_class handling

["IKEDA, Munehiro" <m-ikeda ds jp nec com>]

Hi Gui,

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

Users can specify a device file of a partition for io.policy.
In this case, io_policy_node::dev_name is set as a name of the
partition device like /dev/sda2.

ex)
 # cd /mnt/cgroup
 # cat /dev/sda2:500:2 > io.policy
 # echo io.policy
   dev weight class
   /dev/sda2 500 2

I believe io_policy_node::dev_name should be set a generic
device name like /dev/sda.
What do you think about it?

Signed-off-by: Munehiro "Muuhh" Ikeda <m-ikeda ds jp nec com>
---
block/elevator-fq.c |    7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index 39fa2a1..5d3d55c 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -1631,11 +1631,12 @@ static struct io_policy_node *policy_search_node(const struct io_cgroup *iocg,
	return NULL;
}

-static int devname_to_devnum(const char *buf, dev_t *dev)
+static int devname_to_devnum(char *buf, dev_t *dev)
{
	struct block_device *bdev;
	struct gendisk *disk;
	int part;
+	char *c;

	bdev = lookup_bdev(buf);
	if (IS_ERR(bdev))
@@ -1645,6 +1646,10 @@ static int devname_to_devnum(const char *buf, dev_t *dev)
	*dev = MKDEV(disk->major, disk->first_minor);
	bdput(bdev);

+	c = strrchr(buf, '/');
+	if (c)
+		strcpy(c+1, disk->disk_name);
+
	return 0;
}

--
1.5.4.3


--
IKEDA, Munehiro
 NEC Corporation of America
   m-ikeda ds jp nec com