[OpenAFS-devel] datagrams really arent big enough?

[Chas Williams]

In message <200011071227.HAA21048@oo.yi.org>,Default writes:
>1. try again with 3.6 - rx is summat different now.

i dont believe there is a different.  openafs clients talking to my modified
afs servers dont use every use a packet size bigger than ~5700.

>2. did you measure performance before and after?  I wouldn't think you'd see 
>much more than a couple of percent better transfer rates.

well you wont exactly see a performance difference.  the real bottleneck
is really the cache.  however, i would like to see my mtu size put to use.
eventually we will take care of the cache speed problem.  we are looking
into a 'cache bypass' for 'certain' files.  its certainly more efficient to
recv 1 packet instead of 2.

>The reason PACKET_SIZE is apparently "too large" is to permit changing 
>MAX_FRAGS on the fly, and still be compatible with all the other clients & 
>servers in your network.  It wasn't an oversight.

however MAX_FRAGS isnt large enough to ever take advantage of the PACKET_SIZE
with a value of 4, the biggest packet you will ever see if something like
~5700.  clients and server negotiate the size of packets to be used (based
on the interface mtu among other things)  MAX_FRAGS seems to limit the 
upper end of packet sizes.