Jeffrey Hutzelman wrote:
--On Wednesday, October 08, 2008 12:15:59 PM -0400 Jeffrey Altman
<[EMAIL PROTECTED]> wrote:
Hartmut Reuter wrote:
After integration of my object storage stuff into 1.4.8pre1 I have made
some tests between two of our cell's fileserver machines,
Both Quadcore Intel(R) Xeon(R) CPU E5405 @ 2.00GHz
with 4 GB main memory. They are both on the same Gbit-Ethernet switch.
On the client I use 64 MB memory cache with chunk size 64 KB.
Why such a small chunk size?
A good question. This will adversely affect the transfer rates through
the cache manager, because a separate RXAFS_FetchData is done for each
chunk. What size reads is afsio doing? If they're not the same, then
the measurements are really not comparable.
-- Jeff
Normally I use 256 KB, but I think these 64 K are kind of a default
value. With 64 MB it's not reasonable to use 1 MB chunk size because
then you would have only 64 chunks at all.
It's true: afsio uses 1MB chunks and is therefore better off here. But
the big advantage of Matt's bapass cache seems to be the parallelism you
can get with multi processor machines (On my laptop it's slower than
normal). The effective transfer size of Matt's code seems to be 128 K,
but obviously the number of RPCs isn't the problem, but some kind of
blocking (locking?). Otherwise a simple doubling of throughput is hard
to explain...
-Hartmut
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Hartmut Reuter e-mail [EMAIL PROTECTED]
phone +49-89-3299-1328
fax +49-89-3299-1301
RZG (Rechenzentrum Garching) web http://www.rzg.mpg.de/~hwr
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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