To: Chris Browne <cbbrowne@acm.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Status of Opteron vs Xeon 
In-reply-to: <60r7axjkpj.fsf@dba2.int.libertyrms.com> 
References: <Pine.LNX.4.64.0510061654080.21147@discord.dyndns.org>
	<60r7axjkpj.fsf@dba2.int.libertyrms.com>
Comments: In-reply-to Chris Browne <cbbrowne@acm.org>
	message dated "Fri, 07 Oct 2005 13:33:28 -0400"
Date: Fri, 07 Oct 2005 14:44:37 -0400
Message-ID: <6429.1128710677@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Chris Browne <cbbrowne@acm.org> writes:
> jeff@frostconsultingllc.com (Jeff Frost) writes:
>> What's the current status of how much faster the Opteron is compared
>> to the Xeons?  I know the Opterons used to be close to 2x faster,
>> but is that still the case?  I understand much work has been done to
>> reduce the contect switching storms on the Xeon architecture, is
>> this correct?

> Work has gone into 8.1 to try to help with the context switch storms;
> that doesn't affect previous versions.

Also note that we've found that the current coding of the TAS macro
seems to be very bad for at least some Opterons --- they do much better
if the "pre-test" cmpb is removed.  But this is not true for all x86_64
chips.  We still have an open issue about what to do about this.

			regards, tom lane