On Mon, 1 Oct 2007, Bruce Evans wrote:
On Sun, 30 Sep 2007, Jeff Roberson wrote:
On Sat, 29 Sep 2007, Kevin Oberman wrote:
YMMV, but ULE seems to generally work better then 4BSD for interactive
uniprocessor systems. The preferred scheduler for uniprocessor servers
is less clear, but many test have shown ULE does better for those
systems in the majority of cases.
I feel it's safe to say desktop behavior on UP is definitely superior.
This is unsafe to say.
Given that the overwhelming amount of feedback by qualified poeple, I
think it's fair to say that ULE gives a more responsive system under load.
I think there is no significant difference on UP between 4BSD and ULE
This may be safe to say, but is inconsistent with the above.
I meant no significant difference in performance. I'm sure there are
corner case workloads in favor of one or the other.
except perhaps in context switching microbenchmarks where ULE falls behind.
It is safe to say that interactive users cannot notice insignificant
differences. It takes a micro-benchmark to notice possibly-significant
differences of hundreds or even thousands of nanonseconds for context
switching.
ULE may give higher priority to interactive processes, but most loss of
interactivity is caused by blocking on I/O, and there is nothing nothing
a scheduler can do to speed up slow or overloaded devices.
There is a significant enough class of problems that benefit from the
improved interactive priorities that people notice it. I have heard
reports from a number of laptop users who can run at lower power levels
using ULE. I am trivially able to create workloads where 4bsd falls over
well before ULE. It is true that io behavior dominates in many cases but
that's really a seperate issue.
Jeff
Bruce
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