Re: Wierd context-switching issue on Xeon

Here's an interesting link that suggests that hyperthreading would be
much worse.


http://groups.google.com/groups?q=hyperthreading+dual+xeon+idle&start=10&hl=en&lr=&ie=UTF-8&c2coff=1&selm=aukkonen-FE5275.21093624062003%40shawnews.gv.shawcable.net&rnum=16

another which has some hints as to how it should be handled


http://groups.google.com/groups?q=hyperthreading+dual+xeon+idle&start=10&hl=en&lr=&ie=UTF-8&c2coff=1&selm=u5tl1XD3BHA.2760%40tkmsftngp04&rnum=19
FWIW, I have anecdotal evidence that suggests that this is the case, on
of my clients was seeing very large context switches with HTT turned on,
and without it was much better.

Dave
On Sun, 2004-04-18 at 23:19, Tom Lane wrote:
> >> What about hypterthreading does it still happen if HTT is turned off ?
>
> > The problem comes from keeping the caches synchronized between multiple
> > physical CPUs.  AFAICS enabling HTT wouldn't make it worse, because a
> > hyperthreaded processor still only has one cache.
>
> Also, I forgot to say that the numbers I'm quoting *are* with HTT off.
>
>             regards, tom lane
>
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Dave Cramer
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