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SubjectRe: AIM7 40% regression with 2.6.26-rc1

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> In contrast, these "try to emulate bad behavior with the old known-ok
> semaphores" don't show anything AT ALL. We already know it's related
> to semaphores. And your patches aren't even guaranteed to show the
> same issue.

yeah, i was just trying to come up with patches to probe which one of
the following two possibilities is actually the case:

- if the regression is due to the difference in scheduling behavior of
new semaphores (different wakeup patterns, etc.), that's fixable in
the new semaphore code => then the BKL code need not change.

- if the regression is due due to difference in the fastpath cost, then
the new semaphores can probably not be improved (much of their appeal
comes from them not being complex and not being in assembly) => then
the BKL code needs to change to become cheaper [i.e. then we want
your patch].

Ingo


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