On 03/01/2018 3:05 PM, Zhaoxuan wrote: > > On 03/01/2018 13:45 PM, Coly Li wrote: >> On 03/01/2018 12:39 PM, Zhai Zhaoxuan wrote: >>> The function cached_dev_make_request() and flash_dev_make_request() call >>> generic_start_io_acct() with (struct bcache_device)->disk when they >>> start a >>> closure. Then the function bio_complete() calls generic_end_io_acct() >>> with >>> (struct search)->orig_bio->bi_disk when the closure has done. >>> Since the `bi_disk` is not the bcache device, the >>> generic_end_io_acct() is >>> called with a wrong device queue. >>> >>> It causes the "inflight" (in struct hd_struct) counter keep increasing >>> without decreasing. >>> >>> This patch fix the problem by calling generic_end_io_acct() with >>> (struct bcache_device)->disk. >>> >>> Signed-off-by: Zhai Zhaoxuan <kxuanobj@xxxxxxxxx> >> Hi Zhaoxuan, >> >> Nice catch, it makes sense. Thanks. >> >> Reviewed-by: Coly Li <colyli@xxxxxxx> >> >> One more question, do you experience any problem when inflight counter >> increases only ? I just wondering. > > Hi Coly, > > Thanks for your review. > > There is a problem in `iostat -x`. `iostat` shows the bcache device keep > 100.00% > busy (100.00 in the "%util" column), even if the bcache is idle. > > [root@base ~]# iostat -x -d 1 > Linux 4.15.0-rc6-ARCH (base) 01/03/18 _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 > vda 7.85 1.07 69.98 13.20 1818.60 158.20 > 47.54 0.04 1.08 0.67 3.28 0.30 2.47 > vdb 0.00 0.00 2.61 0.00 75.80 0.00 > 58.09 0.00 0.75 0.75 0.00 0.00 0.00 > bcache0 0.00 0.00 1.98 0.00 52.00 0.00 > 52.64 77.73 1.06 1.06 0.00 485.93 96.00 > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s > avgrq-sz avgqu-sz await r_await w_await svctm %util > vda 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 > vdb 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 81.00 0.00 0.00 0.00 0.00 100.00 > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s > avgrq-sz avgqu-sz await r_await w_await svctm %util > vda 0.00 9.00 0.00 2.00 0.00 44.00 > 44.00 0.00 10.00 0.00 10.00 0.00 0.00 > vdb 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 81.00 0.00 0.00 0.00 0.00 100.00 > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s > avgrq-sz avgqu-sz await r_await w_await svctm %util > vda 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 > vdb 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 81.00 0.00 0.00 0.00 0.00 100.00 > > ^C > [root@base ~]# bcache-super-show /dev/vdb > sb.magic ok > sb.first_sector 8 [match] > sb.csum 54824DA53D2DC101 [match] > sb.version 1 [backing device] > > dev.label (empty) > dev.uuid c5e43e66-4b28-48d7-bd46-73fb6e1efdbb > dev.sectors_per_block 1 > dev.sectors_per_bucket 1024 > dev.data.first_sector 16 > dev.data.cache_mode 0 [writethrough] > dev.data.cache_state 1 [clean] > > cset.uuid a79f8422-ed64-4b92-8688-692f48cd6d97 > [root@base ~]# bcache-super-show /dev/vda2 > sb.magic ok > sb.first_sector 8 [match] > sb.csum EF7AB1A8928862E6 [match] > sb.version 3 [cache device] > > dev.label (empty) > dev.uuid 5762b745-77f8-4831-81ce-9ee7866b8d84 > dev.sectors_per_block 1 > dev.sectors_per_bucket 1024 > dev.cache.first_sector 1024 > dev.cache.cache_sectors 2096128 > dev.cache.total_sectors 2097152 > dev.cache.ordered yes > dev.cache.discard no > dev.cache.pos 0 > dev.cache.replacement 0 [lru] > > cset.uuid a79f8422-ed64-4b92-8688-692f48cd6d97 > Hi Zhaoxuan, Cool, this is an already reported issue but I still have no idea how to fix it yet... Thank you for the fix and the above detailed information! Coly Li
