Questions on the scheduler
wmoran at potentialtech.com
Mon Sep 24 09:22:34 PDT 2007
In response to "Jim Stapleton" <stapleton.41 at gmail.com>:
> I've heard a lot of winging about the FreeBSD scheduler from Linux
> people, and even saw that is the reason for one fork off of FreeBSD.
> In my experience, I've gotten better performance out of FreeBSD on
> single or multi-CPU systems than I have out of Linux or Windows (or
> really any other system).
> Are these complains I hear of outdated, am I hallucinationg, or is
> there another answer? Although this is probably a better question for
> -current, what is the state of the scheduler(s), and what would be
> some good reading on the subject (specifically to BSD, and not just
> schedulers in general)?
Any discussion regarding such things is obsolete as quickly as it's
written. Every OS I know if is constantly working to improve such
things. Getting reliable, high-performance scheduling on modern SMP
hardware is tough, but they all keep improving.
Without a specific problem referencing a specific version, it's just
idle chatter and useless for anything other than exercising your jaw
If you have a specific performance problem, I highly recommend you
file a PR with plenty of details. This is what happened with both
MySQL and PostgreSQL and the result is that FreeBSD 7's ability to
run those applications has improved dramatically.
I doubt you're hallucinating, but without specifics, it's difficult
to say what you're hearing. Lots of people think they can do
benchmarking, but few (in my experience) are capable of legitimately
doing a non-biased comparison that can really be trusted.
I don't know where to point you for reading materials other than the
code itself, and that's not something that's easily digested. As I
said, writing high-quality schedulers is black magic, and the code
reads that way.
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