[UniMacTech] Debugging AFP high CPU usage

[Stewart Lawler]

Hi All..

I'm looking for info to help me get to the bottom of the widely- 
bemoaned but apparently little-fixed CPU usage 'bug' in AppleFileServer.

I'm running 10.5.6 on a 2008 model 8-core Xserve which is as at this  
writing running at about 750% CPU with load average hovering around  
100(!). As reported in many of the fora that i'm finding when googling  
this issue, the CPU load will be normal then something seems to  
trigger the AppleFileServer into creeping cpu usage. Odd thing is  
that, on the whole, the box remains reasonably responsive via ssh &  
ARD, and client connections seem to be functioning. There are usually  
around 50 clients connected but of course it doesn't close connections  
so this can sometimes creep up to over 100 until i manually go and  
disconnect sleeping/absent clients in Server Admin.

This bug (or the symptoms of) has been with us in various forms since  
the 10.4 days. We've hoped it'd go away with each dot-point system  
update but no luck so far. I note that there's a new build of  
AppleFileServer included in 10.5.7, but we're holding off on this  
update for the time being. (We'd be interested to hear of any issues  
with that just by the by..)

I've been working through some of the tests on the performance  
evaluation kb at http://support.apple.com/kb/HT1992 but, only having  
vague understanding of what it all means exactly, i'm having a hard  
time making any sense of the numbers. There does seem to be a very  
high number of context switches (in the tens of thousands) in the CSW  
column when i run top -d and the kb article says that could be  
evidence of excessive pthread locking. In the output of plockstat -C  
there's one lock having a count of thousands, well above the total  
which again, the kb article says is.. bad.

And yet after all that.. i'm not sure it's much help to me in finding  
what's triggering the problem in the first place. For now i'm just  
restarting the AFP service from launchd in the small hours, but I'd  
really like to get to the bottom of the issue and I'd appreciate your  
thoughts & suggestions.

thanks,

..S.

----
: Stewart Lawler
: Computer Systems Engineer
: Technical Resource Centre
: Faculty of Arts & Social Sciences
: University of New South Wales
: Phone (02) 9385 3817
: Fax (02) 9385 1340

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://auc.uow.edu.au/pipermail/unimactech/attachments/20090520/b51c08b3/attachment-0001.html