Re: [HACKERS] Assuming that TAS() will succeed the first time is verboten

[Bruce Momjian]

> Alfred Perlstein <[EMAIL PROTECTED]> writes:
> > One trick that may help is calling sched_yield(2) on a lock miss,
> > it's a POSIX call and quite new so you'd need a 'configure' test
> > for it.
> 
> The author of the current s_lock code seems to have thought that
> select() with a zero delay would do the equivalent of sched_yield().
> I'm not sure if that's true on very many kernels, if indeed any...
> 
> I doubt we could buy much by depending on sched_yield(); if you want
> to assume POSIX facilities, ISTM you might as well go for user-space
> semaphores and forget the whole TAS mechanism.


Another issue is that sched_yield brings in the pthreads library/hooks
on some OS's, which we certainly want to avoid.

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