Re: Question about LWLockAcquire's use of semaphores instead of spinlocks

Hi Bob:
We're have been working with an sproc version of postgres and it has improve
performance over a NUMA3 origin 3000 due to IRIX implements round_robin by
default on memory placement instead of first touch as it did on fork. We're
been wondering about replacing IPC shmem with a shared arena to help
performance improve on IRIX. I dont´know if people here in postgres are
interested on specifical ports but it could help you improve your
performance.
Regards
----- Original Message -----
From: "Robert E. Bruccoleri" <bruc(at)stone(dot)congenomics(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <bruc(at)acm(dot)org>; <pgsql-hackers(at)postgresql(dot)org>
Sent: Sunday, July 28, 2002 5:45 AM
Subject: Re: [HACKERS] Question about LWLockAcquire's use of semaphores
instead of spinlocks

> Tom Lane writes:
> >
> >
> > "Robert E. Bruccoleri" <bruc(at)stone(dot)congenomics(dot)com> writes:
> > > On SGI multiprocessor machines, I suspect that a spinlock
> > > implementation of LWLockAcquire would give better performance than
> > > using IPC semaphores. Is there any specific reason that a spinlock
> > > could not be used in this context?
> >
> > Are you confusing LWLockAcquire with TAS spinlocks?
>
> No.
>
> > If you're saying that we don't have an implementation of TAS for
> > SGI hardware, then feel free to contribute one. If you are wanting to
> > replace LWLocks with spinlocks, then you are sadly mistaken, IMHO.
>
> This touches on my question. Why am I mistaken? I don't understand.
>
> BTW, about 5 years ago, I rewrote the TAS spinlocks for the
> SGI platform to make it work correctly. The current implementation
> is fine.
>
> +-----------------------------+------------------------------------+
> | Robert E. Bruccoleri, Ph.D. | email: bruc(at)acm(dot)org |
> | P.O. Box 314 | URL: http://www.congen.com/~bruc |
> | Pennington, NJ 08534 | |
> +-----------------------------+------------------------------------+
>
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