Hi Stefan,
You might want to try running sysprof or perf while the OSDs are running
during the tests and see where CPU time is being spent. Also, how are
you determining how much CPU usage is being used?
Mark
On 11/08/2012 08:58 AM, Stefan Priebe - Profihost AG wrote:
Is there any way to find out why a ceph-osd process takes around 10
times more load on rand 4k writes than on 4k reads?
Stefan
Am 07.11.2012 21:41, schrieb Stefan Priebe:
Hello list,
whiling benchmarking i was wondering, why the ceph-osd load is so
extreme high while having random 4k write i/o.
Here an example while benchmarking:
random 4k write: 16.000 iop/s 180% CPU Load in top from EACH ceph-osd
process
random 4k read: 16.000 iop/s 19% CPU Load in top from EACH ceph-osd
process
seq 4M write: 800MB/s 14% CPU Load in top from EACH ceph-osd process
seq 4M read: 1600MB/s 9% CPU Load in top from EACH ceph-osd process
I can't understand why in this single case the load is so EXTREMELY high.
Greets
Stefan
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