[OpenAFS-devel] fileserver profiling

[Troy Benjegerdes]

On Mon, Mar 14, 2005 at 07:28:54AM -0500, chas williams - CONTRACTOR wrote:
> In message <20050314040142.GN9768@kalmia.hozed.org>,Troy Benjegerdes writes:
> >I just switched to a 100mb cache, (previously it was 1GB), and ran afsd
> >with "afsd -memcache -chunksize 16", and now I'm getting a better, but
> >not optimal throughput of around 25MB/sec.
> >
> >(Out of curiosity, what cache sizes do people generally run at?)
> 
> generally speaking memcache is going to be faster.  if you have a 
> good link to the fileservers (and network traffic doesnt bother 
> you) then memcache is going to be the way to go.
> 
> increasing chunksize is always going to help with larger files.  if i
> had to guess, i would say afs (fileserver/cache manager) was tuned to
> handle a huge number of tiny files.  since performance on tiny files
> is always dominated by system overhead, the fileserver's performance
> 'problems' aren't a big deal.  however, when it comes to large files
> you start to see trouble.

Yes, chunksize seems to be a big deal. I'm up to about 25-30MB/sec with 
-chunksize 20 

Now, if I could only umount /afs without a kernel panic, I'd probably
write myself a nice script to run benchmarks with a bunch of different
chunk sizes. ;)