NFS Performance

[Steven Johnson]

Hi,

We are using the NFS Client stack as found in the RTEMS CVS.  We
experienced the slow performance that the readme talks about.  We were
getting around 3.5Mbit/s on a 100MBit link.  Our Processor is a 100Mhz
MPC862, and we are using the FEC.

This isn't fast enough for us, as we need around 6-7 Mbit/s so we can
read media files and play them in real time from the NFS Share.

So we investigated the causes.

The single biggest thing we found is BUFSIZ in stdio.h.

It was defined as 1024, which gave us ~3.5Mbit/s
We Changed it to 8192, and NFS Performance on our board jumped to
~19.53MBit/s
We also tried 32768, which gave us ~19.99MBit/s

(This is all Read performance, we don't know how fast write is, because
we don't write with our application).

Also, the readme for the NFS Client indicates performance sucks due to a
lack of read ahead buffering.  Changing BUFSIZ to 8192 seems to provide
read ahead buffering, because if we read 512 bytes, 8192 bytes are
transferred from the file, and another request for 8192 bytes only
occurs when we have exhausted that data.

Anyway, I'm just reporting this so that anyone else who needs NFS to
perform better can know what we did to achieve dramatic speed increases.

Steven J