Re: Hyper-Trading

"Andrej Ricnik-Bay" <andrej(dot)groups(at)gmail(dot)com> writes:
> On 7/11/07, Andrew Sullivan <ajs(at)crankycanuck(dot)ca> wrote:
>> But notice that hyperthreading imposes its own overhead. I've not
>> seen evidence that enabling hyperthreading actually helps, although I
>> may have overlooked a couple of cases.

> Have a look at these:
> http://www.ibm.com/developerworks/linux/library/l-htl/
> http://www.2cpu.com/articles/41_6.html

Conventional wisdom around here has been that HT doesn't help database
performance, and that IBM link might provide a hint as to why: the
only item for which they show a large loss in performance is disk I/O.
Ooops.

Personally I keep HT turned on on my devel machine, because I do find
that recompiling Postgres is noticeably faster ("make -j4" rocks on a
dual Xeon w/HT). I doubt that's the benchmark of greatest interest
to the average *user* of Postgres, though.

regards, tom lane