CAM

Regarding CAM:
I'm waiting for the ftp return of CAM stuff at present.

Im a little apprehensive about having 4 processes between a disk read and the
disk:
client ==> disk-FS ==> PDRV ==> XPT ==> SIM ==> disk
[ and back - though this MAY be shorter ]
Noting that each one is a context switch even if the data is 'copied'
using VM mappings, the registers and VM mapping must be saved and flushed etc

I expect that the XPT can be mapped into either the PDRV or the SIM.
Which is better depends on a more detailed analysis of CAM.

This also leads me to wonder about about a secondary server-process interface,
based on procedure calls instead of msg passing.
Msg passing has advantages during debugging and potentially on MP systems,
however on Uniprocessors where known inter-server dependencies exist a
procedural interface MAY have an advantage.

regards
JonT
Received on Wed Sep 15 01:26:44 1993