Re: ceph-osd cpu usage

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 15.11.2012 16:14, schrieb Sage Weil:
> On Thu, 15 Nov 2012, Stefan Priebe - Profihost AG wrote:
>> Hello list,
>>
>> my main problem right now is that ceph does not scale for me (more vms using
>> rbd). It does not scale as the ceph-osd is using all my CPU core all the time
>> (8 cores) with just 4 SSDs. The SSDs are far away from being loaded.
>>
>> What is the best way to find out what the ceph-osd process is doing all the
>> time?
>>
>> A gperf graph is attached.
>
> Hmm, most significant time seems to be in the allocator and doing
> fsetxattr(2) (10%!).  Also some path traversal stuff.
>
> Can you try the wip-fd-simple-cache branch, which tries to spend less time
> closing and reopening files?  I'm curious how much of a different it will
> make for you for both IOPS and CPU utilization.

Will try that this evening.

> It is also possible to use leveldb for most attrs.  If you set
> 'filestore xattr use omap = true' it should put most attrs in leveldb.

Do i have to recreate the cephfs?

Stefan