Question about throughput

[Mads Bondo Dydensborg]

Hi there.

I have modified a aic7xxx driver to work via a SCI network, to drive disks
in remote systems, as the subject of my Comp. Sci. master's
thesis. (http://www.diku.dk/users/madsdyd/dread/)

It works nicely. However, for reading, I only get about 50 % of the
throughput I expect. Writing works with approx. 100 % of the local case.
This means that I have a situation where I can write to the disk with,
say, 12 MB/s and read with only 6. I believe this is not a problem with my
code, since the same numbers with a 4 disk soft raid system is 49 MB/s
(writing) and 27 MB/s (reading). I have tried to analyze what happens, and
it seems that the aic7xxx driver will only issue a single read command at
a time. When writing, multiple write commands will be issued. 

Obviously, using the SCI network is not the same as the local case. There
is a greater latency for operations. 

My question is this; are there any way to force the aic7xxx driver to
issue more read commands to a device? 

Any help, hints, suggestions, comments, flames are welcome. Anything,
really. :-) I must defend my results in 3 weeks, and would _really_ like
to have solved this problem first. 

Thanks,

Mads

-- 
Mads Bondo Dydensborg.                               madsdyd at challenge.dk
Men of vast integrity are seldom popular.  They are often crucified

                               - Dave Mallery



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