Messages in this thread | | | Subject | Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning | From | Peter Zijlstra <> | Date | Tue, 06 Apr 2010 16:51:18 +0200 |
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On Tue, 2010-04-06 at 07:47 -0700, Ulrich Drepper wrote: > On Tue, Apr 6, 2010 at 01:48, Peter Zijlstra <peterz@infradead.org> > wrote: > > try > > spin > > try > > syscall > > 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".
That's where the FUTEX_LOCK thing comes in, it does all those, the above was a single spin loop to amortize the syscall overhead.
I wouldn't make it any more complex than a single pause ins, syscalls are terribly cheap these days.
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