Re: [patch] new-task-fix.patch, 2.6.8.1-mm1

[Nick Piggin <piggin@cyberone.com.au>]

Ingo Molnar wrote:

>* Rusty Russell <rusty@rustcorp.com.au> wrote:
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>>Looking through 2.6.8.1-mm1, I see this code which doesn't make sense:
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>>So, first off, the statements under "if (unlikely(cpu != this_cpu))"
>>can be folded into the previous block, since that's under the same
>>test.  Secondly, why is sleep_avg being set twice to the same thing,
>>and why are we happy to adjust it the first time without holding the
>>rq lock for current, but the second time we make sure we are holding
>>the rq lock? [...]
>>    
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>agreed, this is a bug - the code has rotten somewhat. The attached patch
>fixes it. I've also cleaned up the locking and added this_rq, to make
>clear when and how we are hopping from one runqueue to another. (this
>cleanup would have made the original bug more obvious as well.)
>
>This comes after sched-nonlinear-timeslicespatch.patch in 2.6.8.1-mm1. 
>Tested on x86.
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Looks OK to me. Thanks Ingo, Rusty.