[OpenAFS] cache manager locked under heavy load?

Simon Wilkinson sxw@inf.ed.ac.uk
Sat, 6 Feb 2010 22:36:16 +0100

On 6 Feb 2010, at 21:54, Jason Edgecombe wrote:

> I'm not familiar with the error, but the fact that "vcache" is in the =
message suggests that you vnode/stat cache is not big enough.

The lock that message refers to is in GetVCache. This suggests that =
you're thrashing the vcache - as Jason suggests I'd take a careful look =
at your cache statistics.

I do have some longer term plans for ways of decreasing the contention =
here. Apache really likes the stat() command, and if we could find ways =
of reducing the locking necessary to return results to stat(), web =
serving from AFS could be substantially faster.

On 6 Feb 2010, at 21:43, Russ Allbery wrote:

> We used to see this and then it went away with the current client =
> manager.  What version of OpenAFS are you using on your clients?

I suspect that the work that Derrick did on dynamic vcaches will help =
with this particular case, as it should move cache flushes away from the =
kernel thread that's actually doing the access.