On Wed, Aug 14, 2019 at 2:49 PM Paul Emmerich <[email protected]> wrote:
>
> On Wed, Aug 14, 2019 at 2:38 PM Olivier AUDRY <[email protected]> wrote:
> > let's test random write
> > rbd -p kube bench kube/bench --io-type write --io-size 8192 --io-threads
> > 256 --io-total 10G --io-pattern rand
> > elapsed: 125 ops: 1310720 ops/sec: 10416.31 bytes/sec: 85330446.58
> >
> > dd if=/dev/zero of=test bs=8192k count=100 oflag=direct
> > 838860800 bytes (839 MB, 800 MiB) copied, 24.6185 s, 34.1 MB/s
> >
> > 34.1MB/s vs 85MB/s ....
>
> 34 apples vs. 85 oranges
>
> You are comparing 256 threads with a huge queue depth vs a single
> thread with a normal queue depth.
> Use fio on the mounted rbd to get better control over what it's doing
When you said mounted, did you mean mapped or "a filesystem mounted on
top of a mapped rbd"?
There is no filesystem in "rbd bench" tests, so fio should be used on
a raw block device. It still won't be completely apples to apples
because in "rbd bench" or fio's rbd engine (--ioengine=rbd) case there
is no block layer either, but it is closer...
Thanks,
Ilya
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