On Wed, Mar 02 2016 at 11:06P -0500, Tejun Heo <tj@xxxxxxxxxx> wrote: > 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. OK, I think this should do it. Nikolay and/or others can you test this patch using blkio cgroups controller with LVM devices and report back? From: Mike Snitzer <snitzer@xxxxxxxxxx> Date: Wed, 2 Mar 2016 12:37:39 -0500 Subject: [PATCH] block: transfer source bio's cgroup tags to clone via bio_associate_blkcg() Move btrfs_bio_clone()'s support for transferring a source bio's cgroup tags to a clone into both bio_clone_bioset() and __bio_clone_fast(). The former is used by btrfs (MD and blk-core also use it via bio_split). The latter is used by both DM and bcache. This should enable the blkio cgroups controller to work with all stacking bio-based block devices. Reported-by: Nikolay Borisov <kernel@xxxxxxxx> Suggested-by: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- block/bio.c | 10 ++++++++++ fs/btrfs/extent_io.c | 6 ------ 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/block/bio.c b/block/bio.c index cf75915..25812be 100644 --- a/block/bio.c +++ b/block/bio.c @@ -584,6 +584,11 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src) bio->bi_rw = bio_src->bi_rw; bio->bi_iter = bio_src->bi_iter; bio->bi_io_vec = bio_src->bi_io_vec; + +#ifdef CONFIG_BLK_CGROUP + if (bio_src->bi_css) + bio_associate_blkcg(bio, bio_src->bi_css); +#endif } EXPORT_SYMBOL(__bio_clone_fast); @@ -689,6 +694,11 @@ integrity_clone: } } +#ifdef CONFIG_BLK_CGROUP + if (bio_src->bi_css) + bio_associate_blkcg(bio, bio_src->bi_css); +#endif + return bio; } EXPORT_SYMBOL(bio_clone_bioset); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 392592d..8abc330 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2691,12 +2691,6 @@ struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask) btrfs_bio->csum = NULL; btrfs_bio->csum_allocated = NULL; btrfs_bio->end_io = NULL; - -#ifdef CONFIG_BLK_CGROUP - /* FIXME, put this into bio_clone_bioset */ - if (bio->bi_css) - bio_associate_blkcg(new, bio->bi_css); -#endif } return new; } -- 2.5.4 (Apple Git-61) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
