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

Alfred Perlstein <bright@wintelcom.net> 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.
        regards, tom lane