more on MicroVaxII disk throughput under Ultrix 2.0 -->

[Paul Lansky]

I've done some more investigation of disk throughput under ultrix 2.0 and
higher on MicroVaxII and am beginning to wonder if the problem is not in
the Generic File System overhead.  I earlier was led to understand that
there were some additional timeouts in the 2.0 kernel which provoked an allergic
reaction in the Emulex QD32 controller. But I saw some tests on RA81s under
Ultrix 3.0 which were significantly poorer than what I get to fujis 
(with Emulex QD32) under 1.1.  I first assumed that this could not 
be GFS's fault since I have a data-acquisition driver which calls the 
disk strategy routine directly with a block list, and assumed that this was
circumventing GFS overhead.  But perhaps I'm wrong.  What I fear is that
DEC has decided that future CPUs and busses will catch up with GFS overhead
(throughput on our 8700 is fine) and that MicrovaxIIs will have to suffer
for the time being.   

I'd appreciate any views, experiences, or opinions in this area, as well
as experiences with 4.3 on Microvaxen.  Thanks

Paul Lansky    paul at phoenix.princeton.edu
Music Department
Princeton University