On Fri, 29 Jan 1999, Neil Conway wrote:
> The behaviour is equally likely to change if I run the code under bash
> instead of tcsh - sometimes bash runs it quicker (and REPEATABLY QUICKER
> I mean, not once) and sometimes tcsh runs it quicker. The behaviour
> stays the same for a while until something in the innards of the machine
> (memory-mapping?) changes and then the speed-changing can either invert
> polarity or disappear for a while... Quite often when it disappears I'm
> left with repeated runs giving me the LOWER speed which is a shame.
As Richard said, it's most probably cache line aliasing.
This severely bites me too. On my UP Pentium 100 w/
Triton chipset x11amp used to use 35 to 40% of the
CPU. On my dual P120 w/ Neptune chipset the CPU usage
varies between 60 and 95%.
The huge increase probably comes from the facts that
x11amp is switching CPU too often and the more
primitive L2 cache mapping on Neptune boards.
Both of these can be solved in software -- I guess
that would bring x11amp back to 50% CPU usage...
(Neptune still suffers from bus contention by 2
CPUs and from slightly slower cache logic)
I guess that for 4CPU Xeon systems the problems are
far larger. We really need to look into this for
2.3...
regards,
Rik -- If a Microsoft product fails, who do you sue?
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