`cpupower idle-set -D 0` will help you a lot, yes.
However it seems that not only the bluestore makes it slow. >= 50% of the
latency is introduced by the OSD itself. I'm just trying to understand
WHAT parts of it are doing so much work. For example in my current case
(with cpupower idle-set -D 0 of course) when I was testing a single OSD on
a very good drive (Intel NVMe, capable of 40000+ single-thread sync write
iops) it was delivering me only 950-1000 iops. It's roughly 1 ms latency,
and only 50% of it comes from bluestore (you can see it `ceph daemon osd.x
perf dump`)! I've even tuned bluestore a little, so that now I'm getting
~1200 iops from it. It means that the bluestore's latency dropped by 33%
(it was around 1/1000 = 500 us, now it is 1/1200 = ~330 us). But still the
overall improvement is only 20% - everything else is eaten by the OSD
itself.
--
With best regards,
Vitaliy Filippov
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