Hello,
our performance testing grid has detected a performance regression caused
by commit ab23a77687 ("xfs: per-cpu deferred inode inactivation queues")
with reaim benchmark running 'disk' and 'disk-large' workloads. The
regression has been so far detected on two machines - marvin7 (48 cpus, 64
GB ram, SATA SSD), dobby (64 cpus, 192 GB ram, rotating disk behind
megaraid_sas controller).
The regression reports from mmtests on marvin7 (which from my experience I
find more reliable than dobby) look like:
reaim-io-disk-xfs
Hmean disk-1 3597.12 ( 0.00%) 3636.37 ( 1.09%)
Hmean disk-25 125000.00 ( 0.00%) 121753.25 ( -2.60%)
Hmean disk-49 218424.96 ( 0.00%) 193421.05 * -11.45%*
Hmean disk-73 286649.22 ( 0.00%) 240131.58 * -16.23%*
Hmean disk-97 349339.74 ( 0.00%) 285854.62 * -18.17%*
Hmean disk-121 373456.79 ( 0.00%) 309199.32 * -17.21%*
Hmean disk-145 399449.04 ( 0.00%) 330547.11 * -17.25%*
Hmean disk-169 420049.71 ( 0.00%) 345132.74 * -17.84%*
Hmean disk-193 458795.56 ( 0.00%) 375243.03 * -18.21%*
Stddev disk-1 102.32 ( 0.00%) 117.93 ( -15.25%)
Stddev disk-25 6981.08 ( 0.00%) 4285.17 ( 38.62%)
Stddev disk-49 9523.63 ( 0.00%) 10723.44 ( -12.60%)
Stddev disk-73 9704.22 ( 0.00%) 7946.73 ( 18.11%)
Stddev disk-97 10059.91 ( 0.00%) 6111.28 ( 39.25%)
Stddev disk-121 5730.56 ( 0.00%) 11714.34 (-104.42%)
Stddev disk-145 11154.40 ( 0.00%) 8129.06 ( 27.12%)
Stddev disk-169 4477.30 ( 0.00%) 3558.86 ( 20.51%)
Stddev disk-193 8785.70 ( 0.00%) 13258.89 ( -50.91%)
reaim-io-disk-large-xfs
Hmean disk-1 722.72 ( 0.00%) 721.85 ( -0.12%)
Hmean disk-25 24177.95 ( 0.00%) 24319.06 ( 0.58%)
Hmean disk-49 35294.12 ( 0.00%) 34361.85 ( -2.64%)
Hmean disk-73 43042.45 ( 0.00%) 40896.36 * -4.99%*
Hmean disk-97 48403.19 ( 0.00%) 46044.30 * -4.87%*
Hmean disk-121 52230.22 ( 0.00%) 49347.47 * -5.52%*
Hmean disk-145 54613.94 ( 0.00%) 52333.98 * -4.17%*
Hmean disk-169 57178.30 ( 0.00%) 54745.71 * -4.25%*
Hmean disk-193 60230.94 ( 0.00%) 57106.22 * -5.19%*
Stddev disk-1 18.74 ( 0.00%) 30.19 ( -61.11%)
Stddev disk-25 439.49 ( 0.00%) 809.58 ( -84.21%)
Stddev disk-49 1416.65 ( 0.00%) 603.55 ( 57.40%)
Stddev disk-73 949.45 ( 0.00%) 584.61 ( 38.43%)
Stddev disk-97 689.51 ( 0.00%) 602.76 ( 12.58%)
Stddev disk-121 485.22 ( 0.00%) 612.79 ( -26.29%)
Stddev disk-145 147.37 ( 0.00%) 442.99 (-200.60%)
Stddev disk-169 282.25 ( 0.00%) 613.42 (-117.33%)
Stddev disk-193 970.05 ( 0.00%) 572.59 ( 40.97%)
Note that numbers behind dash (disk-xx) denote the number of reaim
"clients" - i.e., the number of processes reaim runs in parallel.
This reaim workload will create quite some small files, fsync them, do a
few operations on them like read, write, etc. and quickly delete them. This
happens in many processes in parallel so I can imagine the unlink workload
is rather heavy.
To reproduce the workload the easiest is probably to clone mmtests [1],
there's README.md and docs/Tutorial.md about how to run tests. Relevant
configurations are in configs/config-reaim-io-disk-large and
configs/config-reaim-io-disk, you will need to edit these files to set
appropriate test partition (will get wiped) and filesystem. Note that
mmtests do somewhat modify standard reaim benchmark so that it does not
call system("sync") after each operation (you can see modifications we
apply in [2] if you're interested).
I can probably find some time to better understand what's going on on these
machines later this week but if you have some suggestions what to look for,
you're welcome.
Honza
[1] https://github.com/gormanm/mmtests
[2] https://github.com/gormanm/mmtests/blob/master/shellpack_src/src/reaim/reaim-install
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
