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Date: Mon, 8 Aug 2016 23:28:43 -0500 From: Babu Moger <babu.moger@...cle.com> To: Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: Filesystem slow write performance I wasn't able to repro this with mainline. Sorry for the noise. On 8/6/2016 1:49 PM, Babu Moger wrote: > Hi, > > Seeing some terrible write performance with ext3/4 writes. Reads are > fine. > > I have a created loop device and mounted as ext3(tried ext4 also). > > Here is iostat output. await time is pretty high most of the time. > > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s > avgrq-sz avgqu-sz await svctm %util > loop0 0.00 0.00 0.00 133.00 0.00 1064.00 > 8.00 124.14 835.61 7.52 100.00 > dm-0 0.00 0.00 0.00 132.00 0.00 1056.00 > 8.00 1.00 7.52 7.52 99.20 > > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s > avgrq-sz avgqu-sz await svctm %util > loop0 0.00 0.00 0.00 94.00 0.00 752.00 > 8.00 124.18 901.02 10.64 100.00 > dm-0 0.00 0.00 0.00 92.00 0.00 736.00 > 8.00 1.02 11.09 10.87 100.00 > > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s > avgrq-sz avgqu-sz await svctm %util > loop0 0.00 0.00 0.00 132.00 0.00 1056.00 > 8.00 124.56 1329.30 7.58 100.00 > dm-0 0.00 0.00 0.00 141.00 0.00 1128.00 > 8.00 1.08 7.72 7.06 99.60 > > Tags output > [root@...ld-t7 0]# cat tags > nr_tags=128, reserved_tags=0, bits_per_word=5 > nr_free=128, nr_reserved=0 > active_queues=0 > > Here is the output of "echo w > /proc/sysrq-trigger" when the problem > happens. > > Aug 3 12:18:55 build-t7 kernel: kworker/u512:0 D > 00000000009defd4 0 6 2 0x06000000 > Aug 3 12:18:55 build-t7 kernel: Workqueue: writeback > bdi_writeback_workfn (flush-7:0) > Aug 3 12:18:55 build-t7 kernel: Call Trace: > Aug 3 12:18:55 build-t7 kernel: [00000000009dc9e4] schedule+0x24/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000009defd4] > schedule_timeout+0x134/0x220 > Aug 3 12:18:55 build-t7 kernel: [00000000009dc044] > io_schedule_timeout+0x84/0x100 > Aug 3 12:18:55 build-t7 kernel: [00000000006be64c] bt_get+0x10c/0x1e0 > Aug 3 12:18:55 build-t7 kernel: [00000000006be7f4] > blk_mq_get_tag+0x74/0xe0 > Aug 3 12:18:55 build-t7 kernel: [00000000006ba570] > __blk_mq_alloc_request+0x10/0x180 > Aug 3 12:18:55 build-t7 kernel: [00000000006bb9f4] > blk_mq_map_request+0x1d4/0x260 > Aug 3 12:18:55 build-t7 kernel: [00000000006bbd40] > blk_sq_make_request+0x60/0x300 > Aug 3 12:18:55 build-t7 kernel: [00000000006afa58] > generic_make_request+0x78/0xe0 > Aug 3 12:18:55 build-t7 kernel: [00000000006afb44] submit_bio+0x84/0x160 > Aug 3 12:18:55 build-t7 kernel: [00000000005f7cb4] > _submit_bh+0x174/0x200 > Aug 3 12:18:55 build-t7 kernel: [00000000005f7d54] submit_bh+0x14/0x40 > Aug 3 12:18:55 build-t7 kernel: [00000000005fc248] > __block_write_full_page.clone.0+0x2c8/0x500 > Aug 3 12:18:55 build-t7 kernel: [00000000005fc620] > block_write_full_page+0xa0/0xe0 > Aug 3 12:18:55 build-t7 kernel: [00000000100e7d94] > ext3_writeback_writepage+0x134/0x200 [ext3] > Aug 3 12:18:55 build-t7 kernel: [0000000000562798] __writepage+0x18/0x60 > > Aug 3 12:18:55 build-t7 kernel: loop0 D > 00000000009deff4 0 15632 2 0x01000400 > Aug 3 12:18:55 build-t7 kernel: Call Trace: > Aug 3 12:18:55 build-t7 kernel: [00000000009dc9e4] schedule+0x24/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000009deff4] > schedule_timeout+0x154/0x220 > Aug 3 12:18:55 build-t7 kernel: [00000000009dc044] > io_schedule_timeout+0x84/0x100 > Aug 3 12:18:55 build-t7 kernel: [00000000009dcdbc] bit_wait_io+0x3c/0x80 > Aug 3 12:18:55 build-t7 kernel: [00000000009dd1c4] > __wait_on_bit+0x84/0x100 > Aug 3 12:18:55 build-t7 kernel: [000000000055719c] > wait_on_page_bit+0x7c/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000005586a8] > filemap_fdatawait_range+0xc8/0x140 > Aug 3 12:18:55 build-t7 kernel: [00000000005587fc] > filemap_write_and_wait_range+0x3c/0x80 > Aug 3 12:18:55 build-t7 kernel: [0000000000558a58] > __generic_file_write_iter+0xb8/0x140 > Aug 3 12:18:55 build-t7 kernel: [0000000000558bac] > generic_file_write_iter+0xcc/0x1e0 > Aug 3 12:18:55 build-t7 kernel: [00000000007ca000] lo_rw_aio+0x180/0x240 > Aug 3 12:18:55 build-t7 kernel: [00000000007ca260] > do_req_filebacked+0x1a0/0x1c0 > Aug 3 12:18:55 build-t7 kernel: [00000000007ca2b4] > loop_queue_work+0x34/0x80 > Aug 3 12:18:55 build-t7 kernel: [0000000000491944] > kthread_worker_fn+0x44/0x180 > Aug 3 12:18:55 build-t7 kernel: [0000000000491c4c] kthread+0xac/0xe0 > Aug 3 12:18:55 build-t7 kernel: [0000000000406184] > ret_from_fork+0x1c/0x2c > > Aug 3 12:18:55 build-t7 kernel: livecd-creator D > 00000000009deff4 0 15627 2676 0x308000103000400 > Aug 3 12:18:55 build-t7 kernel: Call Trace: > Aug 3 12:18:55 build-t7 kernel: [00000000009dc9e4] schedule+0x24/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000009deff4] > schedule_timeout+0x154/0x220 > Aug 3 12:18:55 build-t7 kernel: [00000000009dc044] > io_schedule_timeout+0x84/0x100 > Aug 3 12:18:55 build-t7 kernel: [00000000009dcdbc] bit_wait_io+0x3c/0x80 > Aug 3 12:18:55 build-t7 kernel: [00000000009dd1c4] > __wait_on_bit+0x84/0x100 > Aug 3 12:18:55 build-t7 kernel: [000000000055719c] > wait_on_page_bit+0x7c/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000005586a8] > filemap_fdatawait_range+0xc8/0x140 > Aug 3 12:18:55 build-t7 kernel: [00000000005587fc] > filemap_write_and_wait_range+0x3c/0x80 > Aug 3 12:18:55 build-t7 kernel: [00000000100e4258] > ext3_sync_file+0x58/0x2c0 [ext3] > Aug 3 12:18:55 build-t7 kernel: [00000000005f54d8] > vfs_fsync_range+0x38/0xa0 > Aug 3 12:18:55 build-t7 kernel: [00000000005f555c] vfs_fsync+0x1c/0x40 > Aug 3 12:18:55 build-t7 kernel: [00000000005f55a8] do_fsync+0x28/0x60 > Aug 3 12:18:55 build-t7 kernel: [00000000005f55f0] > SyS_fdatasync+0x10/0x40 > > I am not an expert on this area. Note that I am bit behind on the > kernel version(but not a whole lot). Working on to recreate this > with latest upstream kernel. Looked at the upstream patches and tried > most of the upstream patches which appear to be related > and nothing helped. Problem is fairly easy to reproduce. Let me know > if you want me to try something. > Thanks > Babu Moger
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