Hi Eric, On 15/05/16 10:08, Tim Small wrote: > On 11/05/16 02:38, Eric Wheeler wrote: >> Ming Lei's patch got in to 4.6 yet, but try this: >> > https://lkml.org/lkml/2016/4/5/1046 >> > >> > and maybe Shaohua Li's patch too: >> > http://www.spinics.net/lists/raid/msg51830.html > I'll give them both a go... I tried both of these on 4.6.0-rc7 without change to the symptoms (cache device continuously read). Then I tried also disabling partial_stripes_expensive prior to registering the bcache device as per your instructions here: https://lkml.org/lkml/2016/2/1/636 and that seems to have improved things, but not fixed them. The cache device is 120G, and dirty_data had got up to 55.3G, but has now dropped down to 44.5G, but isn't going any further... The cache device is being read at a steady ~270 MB/s, and the backing device (dm-crypt) being written at the same rate, but the writes aren't flowing down to the underlying devices (md RAID5, and SATA disks). I'm guessing that these writes are being refused/retried, and are maybe failing due to their size (avgrq-sz showing > 4000 sectors on the backing device)? Disabling the partial stripes expensive maybe just resulted in a few GB of small writes succeeding? # iostat -y -d 2 -x -p /dev/sdf /dev/dm-0 /dev/md2 /dev/bcache0 Linux 4.6.0-rc7+ 16/05/16 _x86_64_ (2 CPU) Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdf 0.00 0.00 413.00 0.00 281422.00 0.00 1362.82 143.18 338.31 338.31 0.00 2.42 100.00 sdf1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdf2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdf3 0.00 0.00 413.00 0.00 281422.00 0.00 1362.82 143.18 338.31 338.31 0.00 2.42 100.00 dm-0 0.00 0.00 0.00 138.50 0.00 280912.00 4056.49 0.00 0.01 0.00 0.01 0.01 0.20 md2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 bcache0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdf 0.00 6.00 412.00 1.50 281806.00 32.00 1363.18 135.19 314.09 314.78 124.00 2.42 100.00 sdf1 0.00 6.00 0.00 1.50 0.00 32.00 42.67 4.10 124.00 0.00 124.00 388.00 58.20 sdf2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdf3 0.00 0.00 412.00 0.00 281806.00 0.00 1367.99 131.10 314.78 314.78 0.00 2.43 100.00 dm-0 0.00 0.00 0.00 138.50 0.00 282388.00 4077.81 0.00 0.01 0.00 0.01 0.01 0.20 md2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 bcache0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cheers, Tim. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
