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SubjectRe: [patch] CFS scheduler, -v6
On Sunday 29 April 2007 18:00, Ingo Molnar wrote:
> * Willy Tarreau <> wrote:
> > > > [...] except for Mike who has not tested recent versions. [...]
> > >
> > > actually, dont discount Mark Lord's test results either. And it
> > > might be a good idea for Mike to re-test SD 0.46?
> >
> > In any case, it might be a good idea because Mike encountered a
> > problem that nobody could reproduce. [...]
> actually, Mark Lord too reproduced something similar to Mike's results.
> Please try those workloads yourself.

I see no suggestion that either Mark or Mike have tested, or for that matter
_have any intention of testing_, the current version of SD without fancy
renicing or anything involved. Willy I grealy appreciate you trying, but I
don't know why you're bothering even trying here since clearly 1. Ingo is the
scheduler maintainer 2. he's working on a competing implementation and 3. in
my excellent physical and mental state I seem to have slighted the two
testers (both?) somewhere along the line. Mike feels his testing was a
complete waste of time yet it would be ludicrous for me to say that SD didn't
evolve 20 versions further due to his earlier testing, and was the impetus
for you to start work on CFS. The crunch came that we couldn't agree that
fair was appropriate for mainline and we parted ways. That fairness has not
been a problem for his view on CFS though but he has only tested older
versions of SD that still had bugs.

Given facts 1 and 2 above I have all but resigned myself to the fact that SD
has -less than zero- chance of ever being considered for mainline and it's my
job to use it as something to compare your competing design with to make sure
that when (and I do mean when since there seems no doubt in everyone else's
mind) CFS becomes part of mainline that it is as good as SD. Saying people
found CFS better than SD is, in my humble opinion, an exaggeration since
every one I could find was a glowing standalone report of CFS rather than any
comparison to the current very stable bug free version of SD. On the other
hand I still see that when people compare them side to side they find SD is
better, so I will hold CFS against that comparison - when comparing fairness
based designs.

On a related note - implementing a framework is nice but doesn't address any
of the current fairness/starvation/corner case problems mainline has. I don't
see much point in rushing the framework merging since it's still in flux.

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