Am 08.11.2012 16:01, schrieb Sage Weil:
On Thu, 8 Nov 2012, 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?
Something like perf or oprofile is probably your best bet. perf can be
tedious to deploy, depending on where your kernel is coming from.
oprofile seems to be deprecated, although I've had good results with it in
the past.
I've recorded 10s with perf - it is now a 300MB perf.data file. Sadly
i've no idea what todo with it next.
would love to see where the CPU is spending most of it's time. This is
on current master?
Yes
I expect there are still some low-hanging fruit that
can bring CPU utilization down (or even boost iops).
Would be great to find them.
Stefan
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