On 09/06/2021 14:33, Ilya Dryomov wrote:
On Wed, Jun 9, 2021 at 1:38 PM Wido den Hollander <wido@xxxxxxxx> wrote:
Hi,
While doing some benchmarks I have two identical Ceph clusters:
3x SuperMicro 1U
AMD Epyc 7302P 16C
256GB DDR
4x Samsung PM983 1,92TB
100Gbit networking
I tested on such a setup with v16.2.4 with fio:
bs=4k
qd=1
IOps: 695
That was very low as I was expecting at least >1000 IOps.
I checked with the second Ceph cluster which was still running v15.2.8,
the result: 1364 IOps.
I then upgraded from 15.2.8 to 15.2.13: 725 IOps
Looking at the differences between v15.2.8 and v15.2.8 of options.cc I
saw these options:
bluefs_buffered_io: false -> true
bluestore_cache_trim_max_skip_pinned: 1000 -> 64
The main difference seems to be 'bluefs_buffered_io', but in both cases
this was already explicitly set to 'true'.
So anything beyond 15.2.8 is right now giving me a much lower I/O
performance with Queue Depth = 1 and Block Size = 4k.
15.2.8: 1364 IOps
15.2.13: 725 IOps
16.2.4: 695 IOps
Has anybody else seen this as well? I'm trying to figure out where this
is going wrong.
Hi Wido,
Going by the subject, I assume these are rbd numbers? If so, did you
run any RADOS-level benchmarks?
Yes, rbd benchmark using fio.
$ rados -p rbd -t 1 -O 4096 -b 4096 bench 60 write
Average IOPS: 1024
Stddev IOPS: 29.6598
Max IOPS: 1072
Min IOPS: 918
Average Latency(s): 0.000974444
Stddev Latency(s): 0.000306557
So that seems kind of OK. Still roughly 1k IOps and a write latency of ~1ms.
But that was ~0.75ms when writing through RBD.
I now have a 16.2.4 and 15.2.13 cluster with identical hardware to run
some benchmarks on.
Wido
Thanks,
Ilya
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