Re: hyperthreaded cpu still an issue in 8.4?

Scott Carey wrote:
>
> But back on topic for HT -- HT doesn't like spin-locks much unless they
> use the right low level instruction sequence rather than actually
> spinning. With the right instruction, the spin will allow the other
> thread to do work... With the wrong one, it will tie up the pipeline.  I
> have no idea what Postgres' spin-locks and tool chain compile down to.
>
I have two hyperthreaded Xeon processors, so this machine thinks it has four
processors. I have not seen the effect of spin locks with postgres. But I
can tell that Firefox and Thunderbird use the wrong ones. When one of these
is having trouble accessing a site, the processor in question goes up to
100% and the other part of the hyperthreaded processor does nothing even
though I run four BOINC processes that would be glad to gobble up the
cycles. Of course, since it is common to both Firefox and Thunderbird,
perhaps it is a problem in the name server, bind. But wherever it is, it
bugs me.

--
   .~.  Jean-David Beyer          Registered Linux User 85642.
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  /( )\ Shrewsbury, New Jersey    http://counter.li.org
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