Re: Linus 2.6.23-rc1

On Sat, 2007-07-28 at 10:50 -0700, Linus Torvalds wrote:

On Sat, 28 Jul 2007, Kasper Sandberg wrote:

First off, i've personally run tests on many more machines than my own,
i've had lots of people try on their machines, and i've seen totally
unrelated posts to lkml, plus i've seen the experiences people are
writing about on IRC. Frankly, im not just thinking of myself.

Ok, good. Has anybody tried to figure out why 3D games seem to be such a
special case?

I know Ingo looked at it, and seemed to think that he found and fixed
something. But it sounds like it's worth a lot more discussion.


Yes, but the various patches i've recieved seems to not solve it, it
simply changed the load at which CFS seemed to perform well.

On irc there has been wild speculation as to whether its the
sched_yield() stuff in most 3d drivers, but my tests with stubbing it
out, and altering behavior has not changed anything.

Okay, i wasnt going to ask, but ill do it anyway, did you even read the
threads about SD?

I don't _ever_ go on specialty mailing lists. I don't read -mm, and I
don't read the -fs mailing lists. I don't think they are interesting.

And I tried to explain why: people who concentrate on one thing tend to
become this self-selecting group that never looks at anything else, and
then rejects outside input from people who hadn't become part of the "mind
meld".

That's what I think I saw - I saw the reactions from where external people
were talking and cc'ing me.

And yes, it's quite possible that I also got a very one-sided picture of
it. I'm not disputing that. Con was also ill for a rather critical period,
which was certainly not helping it all.

Con was extremely polite to everyone, and he did work
with a multitude of people, you seem to be totally deadlocked into the
ONE incident with a person that was unhappy with SD, simply for being a
fair scheduler.

Hey, maybe that one incident just ended up being a rather big portion of
what I saw. Too bad. That said, the end result (Con's public gripes about
other kernel developers) mostly reinforced my opinion that I did the right
choice.

But maybe you can show a better side of it all. I don't think _any_
scheduler is perfect, and almost all of the time, the RightAnswer(tm) ends
up being not "one or the other", but "somewhere in between".

It's not like we've come to the end of the road: the baseline has just
improved. If you guys can show that SD actually is better at some loads,
without penalizing others, we can (and will) revisit this issue.

well, as far as my tests show, the only real difference between SD and
CFS in terms of performance, is 3d, where both will deliver basically
the same FPS in a given application, SD does it smooth, which is the
best way to explain it, what happens with CFS, as i experience it, is
that it seems to burstly allocate ressources.


So what you should take away from this is that: from what I saw over the
last couple of months, it really wasn't much of a decision. The difference
in how Ingo and Con reacted to peoples reports was pretty stark. And no, I
haven't followed the ck mailing list, and so yes, I obviously did get just
a part of the picture, but the part I got was pretty damn unambiguous.

I really think you should try read the SD and RSDL threads on lkml
again, the only place where con havent been extremely fourthcoming was
deep in the thread where Mike was unhappy with SD not giving X more
prioity than fairness dictates..


But at the same time, no technical decision is ever written in stone. It's
all a balancing act. I've replaced the scheduler before, I'm 100% sure
we'll replace it again. Schedulers are actually not at all that important
in the end: they are a very very small detail in the kernel.

Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: Linus 2.6.23-rc1
    ... First off, i've personally run tests on many more machines than my own, ... I don't _ever_ go on specialty mailing lists. ... scheduler is perfect, and almost all of the time, the RightAnswerends ... no technical decision is ever written in stone. ...
    (Linux-Kernel)
  • Re: cannot schedule jobs except as administrator
    ... The machines were then joined to the domain and worked as expected (like the ... The problem here is that the task scheduler should launch the programs and ... let them work as designed not only BEFORE applying the 80 updates to XP Pro, ...
    (microsoft.public.windows.server.sbs)
  • Re: SCHED_4BSD in RELENG_7 disturbs workflow
    ... The switch from RELENG_6 to RELENG_7 went relatively smooth and apart ... scheduler. ... If you think single-core machines are no longer important, ... imagination, though), but I'd rather have a smooth working experience. ...
    (freebsd-current)
  • Re: SCHED_4BSD in RELENG_7 disturbs workflow
    ... The switch from RELENG_6 to RELENG_7 went relatively smooth and apart ... scheduler. ... If you think single-core machines are no longer important, ... imagination, though), but I'd rather have a smooth working experience. ...
    (freebsd-stable)
  • Re: SCHED_4BSD in RELENG_7 disturbs workflow
    ... scheduler. ... If you think single-core machines are no longer important, ... imagination, though), but I'd rather have a smooth working experience. ... unless I try to use my wireless device) and the performance issue ...
    (freebsd-current)
Loading