Messages in this thread | | | Subject | Re: [patch] scheduler: rebalance_tick interval update | From | Darren Hart <> | Date | Mon, 15 Nov 2004 19:50:04 -0800 |
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On Tue, 2004-11-16 at 13:27 +1100, Nick Piggin wrote: > > Nick Piggin wrote: > > > > > Another example, in some ticks, a CPU won't see the updated 'jiffies', > > other > > times it will (at least on Altix systems, this can happen). > > > > > > Note that if you didn't want to have this rash of balancing attempted after > a CPU wasn't able to run the rebalance for a long time, the solution would > be to keep adding the balance interval until it becomes greater than the > current jiffies.
As I mentioned in my last post, I don't think the "synchronized rebalancing" is a real concern since the interval isn't likely to be the same and the CPU_OFFSET macro is already in place to prevent this "rash of balancing" (nice term :-).
> I actually prefer it to try to make up the lost balances, just from the > perspective of gathering scheduler statistics.
IMO, scheduler statistics are not worth running load_balance() for no reason. (And running it two or three times in a row is clearly not accomplishing anything)
> I don't suspect it happens > enough to justify adding the extra logic - Darren, are you actually seeing > problems?
Not seeing in obvious problems, but the existing logic seems incorrect to me (and the term last_balanced is currently misleading). Running load_balance() multiple times in order to catch up seems wasteful to me as well. The current code says something like: run load_balance() 10 times in a second. If the second is almost up and you have only run it 6 times, it will run it 4 times in a row, that just seems wrong to me.
-- Darren Hart <darren@dvhart.com>
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