cort at fsmlabs.com
Fri Feb 9 09:26:42 EST 2001
} statements about which VMM design is best. You can create a wonderful
} engineer solution, but are you solving the problem or simply masking a
Would you characterize AIX as an OS that takes advantage of the VMM design
of the PowerPC? From the benchmarks I did it appeared to suffer the same
problem that Linux/PPC did at that time. The problem being, a
straightforward implementation of the software side of the VM design of the
PowerPC. After some general improvements in the MM system of Linux/PPC we
sped things up by a large amount by doing what you claim is a mistake. We
widened the gap between Linux/PPC and what was probably the best example of
what VM design can come from knowledge of the PPC architecture (in AIX).
AIX can't claim to be doing it better. I was unable to look under the hood
of AIX, of course, but my benchmarks did show that the _ONLY_ thing that
mattered - wall clock time of user apps - was improved. Doing things that
non-PPC way is not a flaw if it results in better performance.
I do stand by our design, and the choices we made, but I'm open to
suggestion for better ways to do it. I can certainly believe there's a lot
of room for improvement. This is linux, though - actual working code speaks
more loudly and clearly than anything else.
Do you have an example of a better way of doing a VM system in Linux/PPC?
We can't change the page table layout. That's something we're stuck with,
in one form or another, in Linux no matter what (not our decision). What
does Kitchewan do for a VM subsystem? Can you give me an overview of the
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