[OpenAFS] afs memcache tuning... lockups in afs_cv_wait

Mike Garrison mcgarr@umich.edu
Thu, 14 Feb 2008 17:10:17 -0500

On Feb 14, 2008, at 3:59 PM, Mike Polek wrote:

> Mike Garrison wrote:
>>> afsd -memcache -blocks 655360 -chunksize 14 -stat 50000 -daemons 6
>>>    -volumes 512 -nosettime
>> I'd suggest tweaking -rxpck to be higher than the default, it may   
>> actually help with the issue you're running into. We use 2000 for  
>> it.  My mind slips me as to why we picked that number at this point.
> Aha... I didn't know you could use that param with afsd. It's not
> in the main docs on the website, and it's not in the comments that
> list the params in afsd.c.

Yup. It's one of those hidden ones that isn't well documented yet.

> What is the default value? It looks like 80, I think....
> I'm a little unclear if that 80 means create 80 rx packets,
> or create 80 "extra" rx packets. I see a total of 130 when
> I boot... is that normal?  How high can that param go?
> And how much memory and what kind does it chew up?

-rxpck sets rx_extraPackets .. which sets the number of *extra* rx  
packets. The default is 80 extra rx packets.

IIRC, one packet is around 1.5kbytes of memory.. as for what kind,  
hopefully someone else can chime in on that...

> I'll do some testing and see how it goes.

Cool. Let me know if it helps.

Mike Garrison