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SubjectRe: More new schedule() results ...


>this is what i suspected. If we are switching 450 threads that also do
>some real work then we are trashing the cache _badly_ already, so pure
>scheduling costs will not matter at all. Most systems (even loaded
>servers) have typically less than 5 runnable processes. So those systems
>will see 15% scheduling slowdown. Some applications might use many threads
>- for those cases your patch is a nice improvement.

Another couple of points.

1) Even with the two tasks sample the 15 % slodown is not evident
because the switching rate is statistically low.

2) My algo use the _same_ _sematics_ used by the old one but do it faster.

Probably You know better then me how many time schedule() is called in a
Linux workstation ( system calls ).
Lowering the time the cpu execute schedule() is not as lowering user mode
code because schedule() code is mostly interrupt protected.
This means a low speed in acknoledging IRQ and hence a worse system response
to events.

This is all,

Davide.




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