Date: Tue, 15 Oct 2013 15:11:33 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>, tglx@linutronix.de, mingo@redhat.com,
        rostedt@goodmis.org, oleg@redhat.com, fweisbec@gmail.com,
        darren@dvhart.com, johan.eker@ericsson.com, p.faure@akatech.ch,
        linux-kernel@vger.kernel.org, claudio@evidence.eu.com,
        michael@amarulasolutions.com, fchecconi@gmail.com,
        tommaso.cucinotta@sssup.it, nicola.manica@disi.unitn.it,
        luca.abeni@unitn.it, dhaval.giani@gmail.com, hgu1972@gmail.com,
        paulmck@linux.vnet.ibm.com, raistlin@linux.it, insop.song@gmail.com,
        liming.wang@windriver.com, jkacur@redhat.com,
        harald.gustafsson@ericsson.com, vincent.guittot@linaro.org,
        bruce.ashfield@windriver.com--no-chain-reply-to
Subject: Re: [PATCH 12/14] sched: make dl_bw a sub-quota of rt_bw
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* Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, Oct 15, 2013 at 02:25:22PM +0200, Ingo Molnar wrote:
> >
> > Really, please make it _symmetric_ ...
> > 
> > Single core systems are becoming a historic curiosity, should we 
> > should justify every piece of extra complexity we add for them.
> > 
> > So I'd rather see obvious SMP code where the UP case works fine too, 
> > and _then_ maybe check a separate patch that adds the UP optimization, 
> > with (object size) numbers proving that it's worth it, etc.
> 
> That's a slightly larger task than it appears; the core scheduler code 
> they rely on with smp doesn't exist on up.
> 
> We can do this but we need to do it scheduler wide.

The scheduler has over 800 #ifdefs or similar preprocessor directives:

  comet:~/tip> git grep '^#' kernel/sched/ | grep -v include | wc -l
  855

I'd like to see this simplified a bit, _especially_ before we add new 
complexity ...

Thanks,

	Ingo
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