On Mon, Jun 01, 2020 at 01:12:05PM -0700, Boris Burkov wrote: > In order to improve consistency and usability in cgroup stat accounting, > we would like to support the root cgroup's io.stat. > > Since the root cgroup has processes doing io even if the system has no > explicitly created cgroups, we need to be careful to avoid overhead in > that case. For that reason, the rstat algorithms don't handle the root > cgroup, so just turning the file on wouldn't give correct statistics. > > To get around this, we simulate flushing the iostat struct by filling it > out directly from global disk stats. The result is a root cgroup io.stat > file consistent with both /proc/diskstats and io.stat. > > Note that in order to collect the disk stats, we needed to iterate over > devices. To facilitate that, we had to change the linkage of a disk_type > to external so that it can be used from blk-cgroup.c to iterate over > disks. > > Signed-off-by: Boris Burkov <boris@xxxxxx> > Suggested-by: Tejun Heo <tj@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun
