Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning

[Ulrich Drepper]

On Tue, Apr 6, 2010 at 01:48, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> Âtry
> Âspin
> Âtry
> Âsyscall

This is available for a long time in the mutex implementation
(PTHREAD_MUTEX_ADAPTIVE_NP mutex type).  It hasn't show much
improvement if any.  There were some people demanding this support for
as far as I know they are not using it now.  This is adaptive
spinning, learning from previous calls how long to wait.  But it's
still unguided.  There is no way to get information like "the owner
has been descheduled".
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