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Re: xeon processors

From: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
To: Scott Marlowe <smarlowe(at)qwest(dot)net>
Cc: Jaime Casanova <systemguards(at)yahoo(dot)com>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: xeon processors
Date: 2004-06-27 06:39:51
Message-ID: 20040627063951.GB13306@dcc.uchile.cl (view raw or flat)
Thread:
Lists: pgsql-hackers
On Sat, Jun 26, 2004 at 07:31:59PM -0600, Scott Marlowe wrote:
> On Fri, 2004-06-25 at 14:13, Jaime Casanova wrote:
> > Hi all,
> >  
> > Can anyone tell me if postgresql has problems with xeon processors? 
> > If so, there is any fix or project of fix it? 
> 
> To PostgreSQL, there's no difference between a dual CPU machine with no
> hyperthreading, and a single CPU machine with hyperthreading.

At some point there was trouble with spinlocks on some of the newer
Xeons (maybe those with hyperthreading?).  I think there was a good deal
of discussion and resulting development because of that.  According to
my archives it seems to be around december 2003.  There's even a CVS
entry, listed by cvs2cl as


2003-12-27 17:58  tgl

        * src/: backend/storage/lmgr/s_lock.c, include/storage/s_lock.h:
          Improve spinlock code for recent x86 processors: insert a PAUSE
          instruction in the s_lock() wait loop, and use test before
          test-and-set in TAS() macro to avoid unnecessary bus traffic.
          Patch from Manfred Spraul, reworked a bit by Tom.

Not sure if this made the 7.4.3 release ...

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"You knock on that door or the sun will be shining on places inside you
that the sun doesn't usually shine" (en Death: "The High Cost of Living")


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