[OpenAFS] 1.3.x memcache performance

[Hartmut Reuter]

Andrej Filipcic wrote:
> Hi,
> 
> I have checked diskcache/memcache performance over an ADSL link.
> The link has 4M download and 512k upload bandwidth. Although there are still 
> problems with disk cache, the copy from afs to local disk is good enough.
> With disk cache the speed is ~400 kbyte/s (tcp speed is 500 kbyte/s).
> Memcahe speed is much lower, between 120 and 160 kbyte/s, depending on the 
> fileserver. Is there any reason (bug) for such a big difference?
> 
> On gigabit network, the copy speed with memcache is never larger than 20 
> mbyte/s, with disk cache it can go up to 70 mbyte/s.

This is not my experience. We see very good performance with memcache on 
the 1.3.77 clients (73 MB/s for write, 43 MB/s for read). Of course this
may depend on your cache parameters. We use -blocks 65336 -chunksize 20.
With the default chunksize you get a rpc for each 8 KB which makes it 
very slow.

Hartmut


> 
> Servers are 1.2.13, the client is 1.3.77.
> 
> Cheers,
> Andrej
> 


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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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