TimeHorse <[EMAIL PROTECTED]> wrote:
> Anyway, on the one hand AmigaOS support where -128 -> p = 0.0 and +127
> -> p = 1.0 would be a good example of why simply using a 41 point UNIX
> scale is defecient in representing all possible priorities, but apart
> from the support AmigaOS argument, you bring up another issue which
> may be dangerous: are priorities linear in nature?
Interestingly enough this was changed in recent linux kernels.
Process levels in linus kernels are logarithmic now, whereas before
they weren't (but I wouldn't like to say exactly what!).
If I run two CPU intensive jobs to busy out both my CPUs, then using
kernel 2.6.22, run
$ python -c 'from time import time
t = time()
for i in xrange(10000000):
pass
print time()-t'
1.36508607864
$ nice -n 10 python -c 'from time import time
t = time()
for i in xrange(10000000):
pass
print time()-t'
4.27783703804
$ nice -n 20 python -c 'from time import time
t = time()
for i in xrange(10000000):
pass
print time()-t'
36.9293899536
You can see that the levels are not linear! A nice 10 job gets 32% of
the CPU of a nice 0 job, but a nice 20 job gets only 4%.
I think you are on to a loser here trying to normalise it across
OSes unfortunately :-(
--
Nick Craig-Wood <[EMAIL PROTECTED]> -- http://www.craig-wood.com/nick
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