On Tue, Apr 23, 2024 at 12:48:05AM +0800, Kemeng Shi wrote: > /sys/kernel/debug/bdi/xxx/stats is supposed to show writeback information > of whole bdi, but only writeback information of bdi in root cgroup is > collected. So writeback information in non-root cgroup are missing now. > To be more specific, considering following case: > > /* create writeback cgroup */ > cd /sys/fs/cgroup > echo "+memory +io" > cgroup.subtree_control > mkdir group1 > cd group1 > echo $$ > cgroup.procs > /* do writeback in cgroup */ > fio -name test -filename=/dev/vdb ... > /* get writeback info of bdi */ > cat /sys/kernel/debug/bdi/xxx/stats > The cat result unexpectedly implies that there is no writeback on target > bdi. > > Fix this by collecting stats of all wb in bdi instead of only wb in > root cgroup. > > Following domain hierarchy is tested: > global domain (320G) > / \ > cgroup domain1(10G) cgroup domain2(10G) > | | > bdi wb1 wb2 > > /* all writeback info of bdi is successfully collected */ > cat stats > BdiWriteback: 2912 kB > BdiReclaimable: 1598464 kB > BdiDirtyThresh: 167479028 kB > DirtyThresh: 195038532 kB > BackgroundThresh: 32466728 kB > BdiDirtied: 19141696 kB > BdiWritten: 17543456 kB > BdiWriteBandwidth: 1136172 kBps > b_dirty: 2 > b_io: 0 > b_more_io: 1 > b_dirty_time: 0 > bdi_list: 1 > state: 1 > > Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun
