Re: [PATCH] 2.6.16 - futex: small optimization (?)

From: Ingo Molnar
Date: Fri Mar 31 2006 - 01:01:25 EST



* Bill Davidsen <davidsen@xxxxxxx> wrote:

> >>>There are no such situations anymore in an optimal userlevel
> >>>implementation. The last problem (in pthread_cond_signal) was fixed
> >>>by the addition of FUTEX_WAKE_OP. The userlevel code you're looking
> >>>at is simply not optimized for the modern kernels.
> >>What are you suggesting here, that the kernel can be inefficient as
> >>long as the user has a way to program around it?
> >
> >What are you suggesting here, that FUTEX_WAKE_UP is a "user way to
> >program around" an inefficiency? If yes then please explain to me why
> >and what you would do differently.
>
> The point I'm making is that even if an application is "not optimized
> for modern kernels" or whatever, there's no reason to ignore
> inefficiencies. [...]

What are you suggesting here, that the implementation of FUTEX_WAKE_UP
is "ignoring inefficiencies"? Please explain why and what you would do
differently to solve that inefficiency.

Ingo
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