[OpenAFS] improving cache partition performance

Marc Dionne marc.c.dionne@gmail.com
Tue, 30 Aug 2011 11:27:52 -0400

On Mon, Aug 29, 2011 at 19:44, Andy Cobaugh <phalenor@gmail.com> wrote:
> On 2011-08-29 at 19:39, Jason Edgecombe ( jason@rampaginggeek.com ) said:
>> I was told that noatime is bad for an AFS cache partition because AFS uses
>> the atime to know when the cache entry was last accessed.
> Oops, looks like you're right, unless someone more knowledgeable says
> otherwise.
> --andy

Someone can correct me, but reading the code it looks to me like the
cache files' atime is only used at startup to initialize the cache
manager's LRU mechanism.  After that, the cache manager takes care of
maintaining counters in an internal structure whenever cache files are
used, without relying on the atime of the underlying filesystem.  If
that's correct, noatime might cause you not to do an ideal (LRU) usage
of files soon after startup, but probably has little impact in the
long run.