On Tue 01-03-22 16:05:54, Richard Weinberger wrote: > Jan, > > ----- Ursprüngliche Mail ----- > > Von: "Jan Kara" <jack@xxxxxxx> > >> Is this expected? > >> Just want to make sure that the said commit didn't uncover an UBIFS issue. > > > > Yes, I think it is expected. Likely the background threshold for UBIFS bdi > > is very small (probably UBIFS is not used much for writeback compared to > > other filesystems). Previously, we just used wb_stat() which returned 0 > > (PCP counter inexact value) and so background writeback didn't trigger. Now > > we use wb_stat_sum() when threshold is small, get exact value of dirty > > pages and decide to start background writeback. > > Thanks for the prompt reply! > > > The only thing is, whether it is really expected that the threshold for > > UBIFS bdi is so small. You can check the values in > > /sys/kernel/debug/bdi/<bdi>/stats. > > BdiDirtyThresh is indeed 0. > > BdiWriteback: 0 kB > BdiReclaimable: 0 kB > BdiDirtyThresh: 0 kB > DirtyThresh: 772620 kB > BackgroundThresh: 385836 kB > BdiDirtied: 0 kB > BdiWritten: 0 kB > BdiWriteBandwidth: 102400 kBps > b_dirty: 0 > b_io: 0 > b_more_io: 0 > b_dirty_time: 0 > bdi_list: 1 > state: 1 Yes, so this looks expected given the BDI wasn't active yet at all... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
