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Re: [BUGS] BUG #2401: spinlocks not available on amd64

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Theo Schlossnagle <jesus(at)omniti(dot)com>, josh(dot)berkus(at)sun(dot)com, robert(dot)lor(at)sun(dot)com, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [BUGS] BUG #2401: spinlocks not available on amd64
Date: 2006-04-30 00:16:16
Message-ID: 200604300016.k3U0GGu13388@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugspgsql-patches
Tom Lane wrote:
> Theo Schlossnagle <jesus(at)omniti(dot)com> writes:
> > I'd remind everyone that the spinlock stuff is entirely optional at 
> > build time.
> 
> Not really.  The performance hit for not having hardware spinlocks is
> so severe that it's not considered a reasonable fallback.
> 
> > I also think it immensely useful to replace all of the tas subsystem 
> > with cas so that one could reliabily lock these atomics with the process 
> > id of the locker.
> 
> I cannot, ever once in my years working on Postgres, remember having
> wanted such a thing.  I am strongly against mucking with the spinlock
> code for mere aesthetics --- it's too fragile and hard to test,
> especially on platforms you don't have ready access to.
> 
> In short, it ain't broken and we don't need to fix it.

Agreed.  Should the new Solaris ASM code be modified?

-- 
  Bruce Momjian   http://candle.pha.pa.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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