[ic] ic process 25% system load

Jon Jensen jon at endpoint.com
Sat Jun 12 09:53:28 EDT 2004

On Fri, 11 Jun 2004, Rick O'Neil wrote:

> Hyperthreading works at the BIOS level, that is to say the OS has no
> knowledge of whether there are two logical CPUs on one physical CPU
> (hyperthreaded) versus two logical CPUs on two physical CPUs (true dual
> processor).

That's not entirely true. On linux, cat /proc/cpuinfo and look at the 
"physical id" and "siblings" fields. Linux knows that 2 of the 4 virtual 
CPUs are actually on the same physical CPU, and it knows which goes with 
which. That helps in scheduling, to keep cache misses to a minimum.

The applications don't know anything about this, of course, unless they've 
been specifically programmed to pay attention.


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