2010-11-12 17:13:28

by Ben Gamari

[permalink] [raw]
Subject: Mounting blkio cgroup hierarchy

I've been trying to configure cgroups and have encountered some very
strange behavior. In particular, when I follow the instructions in
Documentation/cgroups/blkio-controller.txt I quickly reach an error,

$ cd /mnt
$ sudo mkdir -p cgroups/blkio
$ # Confirm it's not already mounted:
$ cat /proc/mounts
rootfs / rootfs rw 0 0
none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
none /dev devtmpfs rw,relatime,size=1993264k,nr_inodes=498316,mode=755 0 0
none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
/dev/disk/by-uuid/7d908a9f-fe46-4a82-bb2b-3fc108c96280 / ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0
none /sys/kernel/debug debugfs rw,relatime 0 0
none /sys/kernel/security securityfs rw,relatime 0 0
none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
/dev/sda1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
gvfs-fuse-daemon /home/ben/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
$ sudo mount -t cgroup -o blkio none /mnt/cgroups/blkio
mount: special device none does not exist

I've done quite a bit of Googling and yet it's very difficult to find
good information on configuring cgroups. I would use the libcg
toolset[1] but every attempt to configure it has ended in frustratingly
vague error messages.

Any ideas?

Cheers,

- Ben


2010-11-12 17:24:21

by Kirill A. Shutemov

[permalink] [raw]
Subject: Re: Mounting blkio cgroup hierarchy

On Fri, Nov 12, 2010 at 12:13:24PM -0500, Ben Gamari wrote:
> Any ideas?

cat /proc/cgroups ?


--
Kirill A. Shutemov

2010-11-12 18:18:19

by Dhaval Giani

[permalink] [raw]
Subject: Re: Mounting blkio cgroup hierarchy

On Fri, Nov 12, 2010 at 6:13 PM, Ben Gamari <[email protected]> wrote:
> I've been trying to configure cgroups and have encountered some very
> strange behavior. In particular, when I follow the instructions in
> Documentation/cgroups/blkio-controller.txt I quickly reach an error,
>
> $ cd /mnt
> $ sudo mkdir -p cgroups/blkio
> $ # Confirm it's not already mounted:
> $ cat /proc/mounts
> rootfs / rootfs rw 0 0
> none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
> none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
> none /dev devtmpfs rw,relatime,size=1993264k,nr_inodes=498316,mode=755 0 0
> none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
> fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
> /dev/disk/by-uuid/7d908a9f-fe46-4a82-bb2b-3fc108c96280 / ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0
> none /sys/kernel/debug debugfs rw,relatime 0 0
> none /sys/kernel/security securityfs rw,relatime 0 0
> none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
> none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
> none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
> /dev/sda1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0
> binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
> gvfs-fuse-daemon /home/ben/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0
> $ sudo mount -t cgroup -o blkio none /mnt/cgroups/blkio
> mount: special device none does not exist
>
> I've done quite a bit of Googling and yet it's very difficult to find
> good information on configuring cgroups. I would use the libcg
> toolset[1] but every attempt to configure it has ended in frustratingly
> vague error messages.
>

If you give us a hint with what error messages you are getting, at the
very least we can work on fixing those up :-)

Dhaval

2010-11-15 00:48:13

by Li Zefan

[permalink] [raw]
Subject: Re: Mounting blkio cgroup hierarchy

Ben Gamari wrote:
> I've been trying to configure cgroups and have encountered some very
> strange behavior. In particular, when I follow the instructions in
> Documentation/cgroups/blkio-controller.txt I quickly reach an error,
>
> $ cd /mnt
> $ sudo mkdir -p cgroups/blkio
> $ # Confirm it's not already mounted:
> $ cat /proc/mounts
> $ sudo mount -t cgroup -o blkio none /mnt/cgroups/blkio
...
> mount: special device none does not exist
>
> I've done quite a bit of Googling and yet it's very difficult to find
> good information on configuring cgroups. I would use the libcg
> toolset[1] but every attempt to configure it has ended in frustratingly
> vague error messages.
>
> Any ideas?
>

I suspect you didn't have blkio enabled in your kernel config.

So see if blkio is listed in /proc/cgroups or/and if CONFIG_BLK_CGROUP
is enabled in your kernel config.

2010-11-15 01:17:46

by Ben Gamari

[permalink] [raw]
Subject: Re: Mounting blkio cgroup hierarchy

On Mon, 15 Nov 2010 08:49:40 +0800, Li Zefan <[email protected]> wrote:
> Ben Gamari wrote:
> > I've been trying to configure cgroups and have encountered some very
> > strange behavior. In particular, when I follow the instructions in
> > Documentation/cgroups/blkio-controller.txt I quickly reach an error,
> >
> > $ cd /mnt
> > $ sudo mkdir -p cgroups/blkio
> > $ # Confirm it's not already mounted:
> > $ cat /proc/mounts
> > $ sudo mount -t cgroup -o blkio none /mnt/cgroups/blkio
> ...
> > mount: special device none does not exist
> >
> > I've done quite a bit of Googling and yet it's very difficult to find
> > good information on configuring cgroups. I would use the libcg
> > toolset[1] but every attempt to configure it has ended in frustratingly
> > vague error messages.
> >
> > Any ideas?
> >
>
> I suspect you didn't have blkio enabled in your kernel config.
>
Doh! I could have sworn I had enabled this. Sorry for the noise!

- Ben