On Wed, Aug 14, 2019 at 2:49 PM Paul Emmerich <paul.emmerich(a)croit.io> wrote:
On Wed, Aug 14, 2019 at 2:38 PM Olivier AUDRY <olivier(a)nmlq.fr> 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