Thin Lock Implementation

[Leandro Lucarella]

Robert Jacques, el 22 de agosto a las 22:43 me escribiste:
> On Fri, 22 Aug 2008 14:08:28 -0400, Leandro Lucarella <llucax at gmail.com> wrote:
> 
> >Bartosz Milewski, el 20 de agosto a las 15:14 me escribiste:
> >>Brad Roberts wrote:
> >>>I'll agree that inbetween is relatively rare, but just because there's
> >>>contention, doesn't require the switch to heavy locks.  In a lot of the code I
> >>>have written, one spin (assuming the spin utilizes rep; nop;) is sufficient for
> >>>the 'blocked' acquire to finish it's acquire.  The use of heavy weight locks in
> >>>that scenario is a net loss.
> >>
> >>A thin lock is not a spin lock. It's an optimization on top of the OS lock
> >>specifically for the no-contention case. If there is contention, the OS lock,
> >>which is part of FatLock, is used. It presumably does its own optimizations, so
> >>calling it "heavy weight" may be unfair.
> >
> >I would love to hear you point on optimizing an OS lock that is already
> >optimized.
> >
> >Is that really necessary? Do you have numbers that back you up?
> >
> >Thank you.
> >
> Assuming the OS lock involves a kernel call

It doesn't (at least in Linux).

-- 
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
----------------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------------
Si pensas que el alma no se ve
el alma sí se ve en los ojos