Re: [Lse-tech] Re: multi-queue scheduler update

[Hubertus Franke]

In the sched_yield benchmark case this is not a problem , because the
threads don't have any memory footprint, all cloned.
The chatroom, I agree with you. However, I assume that these big irons
(8-ways) will be pretty much loaded with at least 1MB cache. Maybe at this
point another cite with an 8-way system and small cache could run this. I
don't know whether those actually exists.

Alternatively, we could setup a smaller 4-way system (we have a 4-way
300MHZ-P-II Xeon, with 512MB cache) that would fit into your class and we
could also collect the numbers on those and post those.

We are automizing the reboot process right now where we are modifying the
lilol.conf so we can run many tests with different "maxcpus=.." unattended.

So little to do, so much time... ahhh make that so little time, so much to
do.

Hubertus Franke
Enterprise Linux Group (Mgr),  Linux Technology Center (Member Scalability)
, OS-PIC (Chair)
email: [e-mail]
(w) 914-945-2003    (fax) 914-945-4425   TL: 862-2003

[e-mail] on 01/19/2001 11:33:34 AM

To:   Hubertus Franke/Watson/IBM@IBMUS
cc:   David Lang <[e-mail]>, Mike Kravetz
      <[e-mail]>, Andrea Arcangeli <[e-mail]>,
      [e-mail], [e-mail]
Subject:  Re: [Lse-tech] Re: multi-queue scheduler update

You might want to rerun the tests with less cache heavy procs.  The 2meg
xeons you are using could distort things from what the average linux user
would see (running with 256-512k cache).
     Nick

On Fri, 19 Jan 2001, Hubertus Franke wrote:

>
> Sure, we are measuring that as well.
> We are running all these benchmarks and configurations that I mentioned
in
> my previous message on
> 1-2-4-6- and 8 way configurations.
> We have posted some preliminary results on older kernels on the website:
>
> http://lse.sourceforge.net/scheduling/prelim.html
>
> MQ scheduler is meaningless for a UP kernel that is only build under the
> SMP flag.
> The priority==tablebased scheduler does make sense to run on a UP (i.e.
not
> SMP compiled) kernel.
> Some more fine-tuning of the current code base might improve that case,
> because affinity is not a concern
> I can simply go to my top table hash, retrieve the first P entry with
> !P->has_cpu and I am ready to go.
>
> Hubertus Franke
> Enterprise Linux Group (Mgr),  Linux Technology Center (Member
Scalability)
> , OS-PIC (Chair)
> email: [e-mail]
> (w) 914-945-2003    (fax) 914-945-4425   TL: 862-2003
>
>
>
> David Lang <[e-mail]>@lists.sourceforge.net on 01/19/2001
> 11:06:37 AM
>
> Sent by:  [e-mail]
>
>
> To:   Mike Kravetz <[e-mail]>
> cc:   Andrea Arcangeli <[e-mail]>,
<[e-mail]>,
>       <[e-mail]>
> Subject:  Re: [Lse-tech] Re: multi-queue scheduler update
>
>
>
> another thing that would be interesting is what is the overhead on UP or
> small (2-4 way) SMP machines
>
> David Lang
>
> On Thu, 18 Jan 2001, Mike Kravetz wrote:
>
> > Date: Thu, 18 Jan 2001 16:52:25 -0800
> > From: Mike Kravetz <[e-mail]>
> > To: Andrea Arcangeli <[e-mail]>
> > Cc: [e-mail], [e-mail]
> > Subject: Re: [Lse-tech] Re: multi-queue scheduler update
> >
> > On Fri, Jan 19, 2001 at 01:26:16AM +0100, Andrea Arcangeli wrote:
> > > On Thu, Jan 18, 2001 at 03:53:11PM -0800, Mike Kravetz wrote:
> > > > Here are some very preliminary numbers from sched_test_yield
> > > > (which was previously posted to this (lse-tech) list by Bill
> > > > Hartner).  Tests were run on a system with 8 700 MHz Pentium
> > > > III processors.
> > > >
> > > >                            microseconds/yield
> > > > # threads      2.2.16-22           2.4        2.4-multi-queue
> > > > ------------   ---------         --------     ---------------
> > > > 16               18.740            4.603         1.455
> > >
> > > I remeber the O(1) scheduler from Davide Libenzi was beating the
> mainline O(N)
> > > scheduler with over 7 tasks in the runqueue (actually I'm not sure if
> the
> > > number was 7 but certainly it was under 10). So if you also use a
O(1)
> > > scheduler too as I guess (since you have a chance to run fast on the
> lots of
> > > tasks running case) the most interesting thing is how you score with
> 2/4/8
> > > tasks in the runqueue (I think the tests on the O(1) scheduler patch
> was done
> > > at max on a 2-way SMP btw). (the argument for which Davide's patch
> wasn't
> > > included is that most machines have less than 4/5 tasks in the
runqueue
> at the
> > > same time)
> > >
> > > Andrea
> >
> > Thanks for the suggestion.  The only reason I hesitated to test with
> > a small number of threads is because I was under the assumption that
> > this particular benchmark may have problems if the number of threads
> > was less than the number of processors.  I'll give the tests a try
> > with a smaller number of threads.  I'm also open to suggestions for
> > what benchmarks/test methods I could use for scheduler testing.  If
> > you remember what people have used in the past, please let me know.
> >
> > --
> > Mike Kravetz                                 [e-mail]
> > IBM Linux Technology Center
> > -
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> >
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