Messages in this thread | | | Subject | Re: [patch] scheduler: rebalance_tick interval update | From | Darren Hart <> | Date | Tue, 16 Nov 2004 07:56:42 -0800 |
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> >This example didn't take into account: > > unsigned long j = jiffies + CPU_OFFSET(this_cpu); > >Which, even if the last_balance's were equal and intervals were the same > >(unlikely since each CPU has it's own domain and the intervals are > >adjusted independently?), > > > > That is correct. > > > would prevent them from both running on the > >same timer tick. So I don't think this example is accurate. On the > >other hand, even if it was valid, I would prefer this to running the > >load_balance code on the same CPU and domain several ticks in a row > >(which obviously accomplishes nothing). > > > > It is valid because the CPU_OFFSET basically just adds a constant amount > to each CPU's 'jiffies'. My example took that into account already and > used the absolute jiffies value. If that doesn't convince you, pretend > that the delay were to occur to CPU0, whos CPU_OFFSET == 0.
Heh, I thought of exactly that case when I rolled out of bed this morning. Funny how that happens sometimes, you can be sitting in front of the code and make what you think is a perfectly valid analysis and then wake up the next morning with no context at all and realize you were wrong. That happens to me anyway :-), I can't be the only one...
Nevertheless, that is a pretty unlikely corner case. They double up only when last_balance+interval is the same and one of the CPUs involved is CPU 0.
> > -- Darren Hart <darren@dvhart.com>
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