Hello, On Thu, Feb 25, 2016 at 09:53:14AM -0500, Mike Snitzer wrote: > Right, LVM created devices are bio-based DM devices in the kernel. > bio-based block devices do _not_ have an IO scheduler. Their underlying > request-based device does. dm devices are not the actual resource source, so I don't think it'd work too well to put io controllers on them (can't really do things like proportional control without owning the queue). > I'm not well-versed on the top-level cgroup interface and how it maps to > associated resources that are established in the kernel. But it could > be that the configuration of blkio cgroup against a bio-based LVM device > needs to be passed through to the underlying request-based device > (e.g. /dev/sda4 in Chris's case)? > > I'm also wondering whether the latest cgroup work that Tejun has just > finished (afaik to support buffered IO in the IO controller) will afford > us a more meaningful reason to work to make cgroups' blkio controller > actually work with bio-based devices like LVM's DM devices? > > I'm very much open to advice on how to proceed with investigating this > integration work. Tejun, Vivek, anyone else: if you have advice on next > steps for DM on this front _please_ yell, thanks! I think the only thing necessary is dm transferring bio cgroup tags to the bio's that it ends up passing down the stack. Please take a look at fs/btrfs/extent_io.c::btrfs_bio_clone() for an example. We probably should introduce a wrapper for this so that each site doesn't need to ifdef it. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
