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Re: [LUG] RH 9.x
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Brough, Tom wrote:
> IIRC HP-UX had a feature that uses (or used to use) sticky bit on
executables to keep them
> in memory even when nobody is using it.
Urm scratched head..... shared libraries maybe, I don't think the
address space was shared/sharable for executable code but shared
libraries had to use position independent code.... But my recollection
is a bit vague.
The only thing I remember clearly was the way the HP-UX boxes crashed
and burned when we were trying out funky optimisations like these. HP-UX
doesn't often crash, so when it happens it tends to stick in your mind.
They had an option for paging out, rather than discarding NFS loaded
code pages as well. The idea being rereading code from the NFS server
might be slower than local swap access.
I suspect we were playing with both these when the boxes were
crashing... it was a little while before I realised it was the
combination of synchronous I/O and NFS, that was causing the worst
performance problems (HP-UX NFS write performance - test it if it is
important to you). I learnt a lot about HP-UX I/O sorting that beastie out.
I also learnt not to fiddle with funky sounding opimisations that aren't
widely used unless you're absolutely sure you need those last few
percentage points of performance.
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