cgroupfs: create /sys/fs/cgroup to mount cgroupfs on
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From: Greg KH on 23 Jul 2010 08:10 On Fri, Jul 23, 2010 at 12:32:26PM +0200, Jan Safranek wrote: > On 07/23/2010 04:07 AM, Vivek Goyal wrote: >> On Thu, Jul 22, 2010 at 04:14:01PM -0700, Greg KH wrote: >>> On Fri, Jul 23, 2010 at 01:08:12AM +0200, Kay Sievers wrote: >>>> On Thu, Jul 22, 2010 at 23:18, Greg KH<gregkh(a)suse.de> wrote: >>>>>> For my testing I now always use /cgroup/ and create directories under it >>>>>> /cgroup/blkio /cgroup/cpu etc and mount controllers on respective >>>>>> directories. >>>>> >>>>> Lennart and Kay, is this what systemd is doing? I really don't think we >>>>> should be adding a root /cgroup/ mount point to the system for something >>>>> like this. >>>> >>>> Already solved. Systemd always mounts an empty tmpfs at the 'cgroup' >>>> mountpoint, and stuff is free to create subdirs there. Systemd itself >>>> mount 'systemd' there. >>> >>> Ah, that makes it easier. Paul and Vivek, any objection to this patch >>> going in now? >>> >> >> This sounds reasonable to me also. >> >> Jan, I know you have been working in this area and raised concenrs about >> cgroup mount point in the past. Does it look good to you? > > I would prefer some place where subdirectories can be created for > individual hierarchies without additional tmpfs there. But as I understand > /sys, it's not an easy feature to implement it there, so no, I am not > against /sys/fs/cgroup. Great, thanks for letting us know. So, who can get this patch into mainline? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Matt Helsley on 23 Jul 2010 16:30 On Fri, Jul 23, 2010 at 01:10:43AM +0200, Kay Sievers wrote: > On Thu, Jul 22, 2010 at 23:48, Matt Helsley <matthltc(a)us.ibm.com> wrote: > > So I'd suggest > > those cgroup mounts go in /var/run/systemd/cgroup or something like that. > > Impossible, we need it at bootup, and / is usually read-only, and /var > might even be behind the network we need to bring up. > > It needs to be on tmpfs mounted on the rootsfs, or in any of the > virtual fss we have to mount anyway, so /sys/fs seems a good place. Ahh, excellent point. Indeed, /sys/fs seems fine then. Cheers, -Matt Helsley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Balbir Singh on 24 Jul 2010 10:20 * Vivek Goyal <vgoyal(a)redhat.com> [2010-07-22 17:26:34]: > On Thu, Jul 22, 2010 at 02:18:56PM -0700, Greg KH wrote: > > On Thu, Jul 22, 2010 at 03:37:41PM -0400, Vivek Goyal wrote: > > > On Thu, Jul 22, 2010 at 11:36:15AM -0700, Greg KH wrote: > > > > On Thu, Jul 22, 2010 at 11:31:07AM -0700, Paul Menage wrote: > > > > > On Thu, Jul 22, 2010 at 11:26 AM, Greg KH <gregkh(a)suse.de> wrote: > > > > > > We really shouldn't be asking userspace to create new root filesystems. > > > > > > So follow along with all of the other in-kernel filesystems, and provide > > > > > > a mount point in sysfs. > > > > > > > > > > > > For cgroupfs, this should be in /sys/fs/cgroup/ �This change provides > > > > > > that mount point when the cgroup filesystem is registered in the kernel. > > > > > > > > > > But cgroups will typically have multiple mounts, with different > > > > > resource controllers/options on each mount. That doesn't really fit in > > > > > with this scheme. > > > > > > > > Really? I see systems mounting it at /cgroups/ in the filesystem today. > > > > Where are you expecting it to be mounted at? > > > > > > > > > > Greg, > > > > > > [CCing few more folks who might be interested in this dicussion ] > > > > > > We do want to retain facility to mount different controllers at different > > > mount points. We were discussing the other day that in libvirt we might > > > want to mount block IO controller and network controller separately as > > > by default we will not put a new virtual machine in a cgroup of its own > > > because of the penatly involved. > > > > That's fine, I'm not changing that ability at all. We just need a > > "default" mount point for "normal" users. > > > > > For other controllers like cpu, memory etc, libvirt automatically puts > > > each new virtual machine in a cgroup of own. So this is one use case > > > where we might want to mount different controllers at different mount > > > points. > > > > > > For my testing I now always use /cgroup/ and create directories under it > > > /cgroup/blkio /cgroup/cpu etc and mount controllers on respective > > > directories. > > > > Lennart and Kay, is this what systemd is doing? I really don't think we > > should be adding a root /cgroup/ mount point to the system for something > > like this. > > > > Maybe /dev/cgroup/ is better to use, as that way users can create > > sub-mount points easier. They can't do that in /sys/fs/cgroup/ > > The only problem with /dev/cgroup seems to be that it seems little > unintutive. To me, we have devices under /dev/ dir and cgroups are not > devices. > > I think people have floated similar threads in the past on lkml with > various opinions and everybody had their own choices but nothing was > conclusive. > > Polluting / definitely sounds odd but it does not look that bad once > we can't find any other good choices. > I think it breaks the filesystem hierarchy standard and I've seen bugzilla's around it. I'd prefer /sys/fs/cgroup. -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Dhaval Giani on 26 Jul 2010 05:10 On Thu, Jul 22, 2010 at 8:36 PM, Greg KH <gregkh(a)suse.de> wrote: > On Thu, Jul 22, 2010 at 11:31:07AM -0700, Paul Menage wrote: >> On Thu, Jul 22, 2010 at 11:26 AM, Greg KH <gregkh(a)suse.de> wrote: >> > We really shouldn't be asking userspace to create new root filesystems. >> > So follow along with all of the other in-kernel filesystems, and provide >> > a mount point in sysfs. >> > >> > For cgroupfs, this should be in /sys/fs/cgroup/ �This change provides >> > that mount point when the cgroup filesystem is registered in the kernel. >> >> But cgroups will typically have multiple mounts, with different >> resource controllers/options on each mount. That doesn't really fit in >> with this scheme. > > Really? �I see systems mounting it at /cgroups/ in the filesystem today. > Where are you expecting it to be mounted at? > Not really. It is getting mounted at /cgroups/<name of resource controller>/ at a number of places. Keeping it in sysfs loses us a lot of this flexibility. Unless you are ready to keep adding a new mountpoint for each subsystem, it will not really work out in the long term. Dhaval -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Kay Sievers on 26 Jul 2010 05:20
On Mon, Jul 26, 2010 at 11:08, Dhaval Giani <dhaval.lists(a)thegianis.in> wrote: > On Thu, Jul 22, 2010 at 8:36 PM, Greg KH <gregkh(a)suse.de> wrote: >> On Thu, Jul 22, 2010 at 11:31:07AM -0700, Paul Menage wrote: >>> On Thu, Jul 22, 2010 at 11:26 AM, Greg KH <gregkh(a)suse.de> wrote: >>> > We really shouldn't be asking userspace to create new root filesystems. >>> > So follow along with all of the other in-kernel filesystems, and provide >>> > a mount point in sysfs. >>> > >>> > For cgroupfs, this should be in /sys/fs/cgroup/ This change provides >>> > that mount point when the cgroup filesystem is registered in the kernel. >>> >>> But cgroups will typically have multiple mounts, with different >>> resource controllers/options on each mount. That doesn't really fit in >>> with this scheme. >> >> Really? I see systems mounting it at /cgroups/ in the filesystem today. >> Where are you expecting it to be mounted at? >> > > Not really. It is getting mounted at /cgroups/<name of resource > controller>/ at a number of places. Keeping it in sysfs loses us a lot > of this flexibility. Unless you are ready to keep adding a new > mountpoint for each subsystem, it will not really work out in the long > term. As mentioned earlier in this thread, systemd already mounts a tmpfs at the cgroup mountpoint. We need only a single directory. This should not be an issue. Kay -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |