Re: Status of Opteron vs Xeon - Mailing list pgsql-performance

From Tom Lane
Subject Re: Status of Opteron vs Xeon
Date
Msg-id 6429.1128710677@sss.pgh.pa.us
Whole thread Raw
In response to Re: Status of Opteron vs Xeon  (Chris Browne <cbbrowne@acm.org>)
List pgsql-performance
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

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