Messages in this thread | | | Date | Fri, 27 Jan 2012 08:56:24 +0800 | From | Michael Wang <> | Subject | Re: [PATCH v2] sched: Accelerate "pick_next_entity" under special condition |
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On 01/25/2012 11:55 PM, Peter Zijlstra wrote:
> On Tue, 2012-01-17 at 11:04 +0800, Michael Wang wrote: >> >>> Then what if condition 1 is true now? >> >> We can see in original code, even condition 1 is true, we >> still will use value3 if condition3 is true, like this: >> >> original: >> >> condition1 condition3 result >> true true value3 >> true false value1 >> >> That means if condition3 is true, we don't care whether >> condition1 is true or not because we will finally use value3. >
> Right, so from the original 8 possible states we used to evaluate 3*8 = > 24 conditionals. The new code will reduce this to 1*4 + 2*2 + 2*3 = 14. > > Now I guess the question is if it matters for the modal or average > state. >
Hi, Peter
I think how much help this patch can do on the performance depends on how often the condition2 and 3 occur.
> I've applied the patch since it can't be worse, but I've no idea if it > matters or not in practice.
It's hardly to say how useful this patch is, but it will do some help under special condition. Thanks for your review.
Regards, Michael Wang
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