** Also affects: linux-azure (Ubuntu Xenial)
Importance: Undecided
Status: New
** Changed in: linux-azure (Ubuntu Xenial)
Status: New => Fix Committed
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https://bugs.launchpad.net/bugs/1828248
Title:
[linux-azure] Storage performance drop on RAID
Status in linux-azure package in Ubuntu:
New
Status in linux-azure source package in Xenial:
Fix Committed
Bug description:
In Azure, FIO 4k tests are showing performance drops on latest proposed
4.15.0 linux-azure kernels - from 52K IOPS to ~38K IOPS (max value reached on
both sequential and random read tests).
The setup used is 12 disks in RAID0.
The affected kernels are:
Ubuntu 14.04 + 4.15.0-1043
Ubuntu 16.04 + 4.15.0-1044
Previous kernel versions had reached max IOPS, ~52K IOPS on both read
tests (e.g. 16.04 + 4.15.0-1043 kernel). Right now, it seems like the
issue is in the diff from 1043 kernel on trusty vs 1044 kernel on
xenial.
The 52K IOPS is expected at qdepth=256. The repro cmd (as ran by the
automation) is this:
fio --size=1023G --direct=1 --ioengine=libaio --filename=/dev/md0
--overwrite=1 --readwrite=randread --bs=4K --runtime=300 --iodepth=32
--numjob=8 --output-format=json
--output=/root/FIOLog/jsonLog/fio-result-randread-4K-256td.json --name='repro'
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