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  1. 17 1月, 2020 19 次提交
  3. 15 1月, 2020 8 次提交
    • J
      alinux: ovl: implement async IO routines · 3e5dd02b
      由 Jiufei Xue 提交于 
      A performance regression is observed since linux v4.19 when we do aio
test using fio with iodepth 128 on overlayfs. And we found that queue
depth of the device is always 1 which is unexpected.

After investigation, it is found that commit 16914e6f
("ovl: add ovl_read_iter()") and commit 2a92e07e
("ovl: add ovl_write_iter()") use do_iter_readv_writev() to submit
requests to real filesystem. Async IOs are converted to sync IOs here
and cause performance regression.

So implement async IO for stacked reading and writing.

Changes since v1:
  - add a cleanup helper for completion/error handling
  - handle the case when aio_req allocation failed
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      3e5dd02b
    • J
      alinux: vfs: add vfs_iocb_iter_[read|write] helper functions · 6011bef7
      由 Jiufei Xue 提交于 
      This isn't cause any behavior changes and will be used by overlay
async IO implementation.
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      6011bef7
    • M
      alinux: fuse: add sysfs api to flush processing queue requests · fc0a9b55
      由 Ma Jie Yue 提交于 
      The failover of fuse userspace daemon will reuse the existing fuse conn,
without unmounting it, during daemon crashing and recovery procedure.
But some requests might be in process in the daemon before sending out reply,
when the crash happens. This will stuck the application since it will
never get the reply after the failover.

We add the sysfs api to flush these requests, after the daemon crash, before
recovery. It is easy to reproduce the issue in the fuse userspace daemon,
just exit after receiving the request and before sending the reply back.
The application will hang up in some read/write operation, before
echo 1 > /sys/fs/fuse/connection/xxx/flush. The flush operation will make
the io fail and return the error to the application.
Signed-off-by: NMa Jie Yue <majieyue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      fc0a9b55
    • X
      alinux: jbd2: add proc entry to control whether doing buffer copy-out · 1ced8a5c
      由 Xiaoguang Wang 提交于 
      When jbd2 tries to get write access to one buffer, and if this buffer
is under writeback with BH_Shadow flag, jbd2 will wait until this buffer
has been written to disk, but sometimes the time taken to wait may be
much long, especially disk capacity is almost full.

Here add a proc entry "force-copy", if its value is not zero, jbd2 will
always do meta buffer copy-cout, then we can eliminate the unnecessary
wating time here, and reduce long tail latency for buffered-write.

I construct such test case below:

$cat offline.fio
; fio-rand-RW.job for fiotest

[global]
name=fio-rand-RW
filename=fio-rand-RW
rw=randrw
rwmixread=60
rwmixwrite=40
bs=4K
direct=0
numjobs=4
time_based=1
runtime=900

[file1]
size=60G
ioengine=sync
iodepth=16

$cat online.fio
; fio-seq-write.job for fiotest

[global]
name=fio-seq-write
filename=fio-seq-write
rw=write
bs=256K
direct=0
numjobs=1
time_based=1
runtime=60

[file1]
rate=50m
size=10G
ioengine=sync
iodepth=16

With this patch:
$cat /proc/fs/jbd2/sda5-8/force_copy
0

online fio almost always get such long tail latency:

Jobs: 1 (f=1), 0B/s-0B/s: [W(1)][100.0%][w=50.0MiB/s][w=200 IOPS][eta
00m:00s]
file1: (groupid=0, jobs=1): err= 0: pid=17855: Thu Nov 15 09:45:57 2018
  write: IOPS=200, BW=50.0MiB/s (52.4MB/s)(3000MiB/60001msec)
    clat (usec): min=135, max=4086.6k, avg=867.21, stdev=50338.22
     lat (usec): min=139, max=4086.6k, avg=871.16, stdev=50338.22
    clat percentiles (usec):
     |  1.00th=[    141],  5.00th=[    143], 10.00th=[    145],
     | 20.00th=[    147], 30.00th=[    147], 40.00th=[    149],
     | 50.00th=[    149], 60.00th=[    151], 70.00th=[    153],
     | 80.00th=[    155], 90.00th=[    159], 95.00th=[    163],
     | 99.00th=[    255], 99.50th=[    273], 99.90th=[    429],
     | 99.95th=[    441], 99.99th=[3640656]

$cat /proc/fs/jbd2/sda5-8/force_copy
1

online fio latency is much better.

Jobs: 1 (f=1), 0B/s-0B/s: [W(1)][100.0%][w=50.0MiB/s][w=200 IOPS][eta
00m:00s]
file1: (groupid=0, jobs=1): err= 0: pid=8084: Thu Nov 15 09:31:15 2018
  write: IOPS=200, BW=50.0MiB/s (52.4MB/s)(3000MiB/60001msec)
    clat (usec): min=137, max=545, avg=151.35, stdev=16.22
     lat (usec): min=140, max=548, avg=155.31, stdev=16.65
    clat percentiles (usec):
     |  1.00th=[  143],  5.00th=[  145], 10.00th=[  145], 20.00th=[
147],
     | 30.00th=[  147], 40.00th=[  147], 50.00th=[  149], 60.00th=[
149],
     | 70.00th=[  151], 80.00th=[  155], 90.00th=[  157], 95.00th=[
161],
     | 99.00th=[  239], 99.50th=[  269], 99.90th=[  420], 99.95th=[
429],
     | 99.99th=[  537]

As to the cost: because we'll always need to copy meta buffer, will
consume minor cpu time and some memory(at most 32MB for 128MB journal
size).
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      1ced8a5c
    • X
      alinux: ext4: don't submit unwritten extent while holding active jbd2 handle · c7c8cb0e
      由 Xiaoguang Wang 提交于 
      In ext4_writepages(), for every iteration, mpage_prepare_extent_to_map()
will try to find 2048 pages to map and normally one bio can contain 256
pages at most. If we really found 2048 pages to map, there will be 4 bios
and 4 ext4_io_submit() calls which are called both in ext4_writepages()
and mpage_map_and_submit_extent().

But note that in mpage_map_and_submit_extent(), we hold a valid jbd2 handle,
when dioread_nolock is enabled and extent is unwritten, jbd2 commit thread
will wait this handle to finish, so wait the unwritten extent is written to
disk, this will introduce unnecessary stall time, especially longer when
the writeback operation is io throttled, need to fix this issue.

Here for this scene, we accumulate bios in ext4_io_submit's io_bio, and
only submit these bios after dropping the jbd2 handle.
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      c7c8cb0e
    • Z
      alinux: fs,ext4: remove projid limit when create hard link · 08e6d768
      由 zhangliguang 提交于 
      This is a temporary workaround plan to avoid the limitation when
creating hard link cross two projids.
Signed-off-by: Nzhangliguang <zhangliguang@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      08e6d768
    • X
      alinux: jbd2: add new "stats" proc file · 7e2e7b9a
      由 Xiaoguang Wang 提交于 
      /proc/fs/jbd2/${device}/info only shows whole average statistical
info about jbd2's life cycle, but it can not show jbd2 info in
specified time interval and sometimes this capability is very useful
for trouble shooting. For example, we can not see how rs_locked and
rs_flushing grows in specified time interval, but these two indexes
can explain some reasons for app's behaviours.

Here we add a new "stats" proc file like /proc/diskstats, then we can
implement a simple tool jbd2_stats which'll display detailed jbd2 info
in specified time interval. Like below(time interval 5s):

[lege@localhost ~]$ cat /proc/fs/jbd2/vdb1-8/stats
51 30 8192 0 1 241616 0 0 22 0 47158 891 942 1000 1000

[lege@localhost ~]$ gcc -o jbd2_stat jbd2_stat.c ; ./jbd2_stat

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             1861       158       359     13.00      0.00
2.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             1974       113       389     26.00      0.00
5.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             2188       214       308     10.00      0.00
7.00

Device              tid     trans   handles    locked  flushing
logging
vdb1-8             2344       156       332     19.00      0.00
4.00
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      7e2e7b9a
    • J
      alinux: jbd2: create jbd2-ckpt thread for journal checkpoint · 3999cdd9
      由 Joseph Qi 提交于 
      This is trying to do jbd2 checkpoint in a specific kernel thread, then
checkpoint won't be under io throttle control.
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Nzhangliguang <zhangliguang@linux.alibaba.com>
Reviewed by: Baoyou Xie <baoyou.xie@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      3999cdd9
  5. 02 1月, 2020 4 次提交
  7. 27 12月, 2019 9 次提交