interpretation of %CPU in 'procps' output for multi-cpu & hyperthreading

Matthew Woehlke
Thu Oct 11 15:58:00 GMT 2007

Tom Rodman wrote:
> I would guess gzip must run on exactly 1 cpu, at any given time.
> If so, then at most, gzip could use 1/8 of the total
> CPU resources or 12.5%, as reported by windows task manager,
> right?  So procps is reporting the percent of the current virtual CPU,
> that gzip is using, right?
> Notice that 'pslist' (from SysInternals) shows gzip, using
> 9%; 9/12.5 * 100 = 72% of 1 virtual CPU.
> Is there a way to prove that a given process with more than 1 thread,
> is still restricted to just one CPU?

Unless you have manually set affinity, why would this be true? More 
likely, only one thread is actually doing anything.

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