Re: [tlug] Re: [RFC] Outline of the fast HTTP talk (PHP benchmark)

[Curt Sampson <cjs@example.com>]

On 2008-11-06 11:45 +0900 (Thu), Stephen J. Turnbull wrote:

> Curt Sampson writes:
> 
>  > To use it otherwise is a confusing misuse of the term. [Insert rant
>  > about Linux folks changing common terminology here.]
> 
> Er, what usage do Linux folks use it for?

According to the schedtool manpage:

    AFFINITY MASK
       The affinity-argument determines on which CPUs a process is
       allowed to run. It consists of a simple bitmask represented in
       hexadecimal.  CPU0 is denoted by the least-significant bit,
       CPU1 by the second  least-significant and so on.

In normal MP usage (e.g., according to Pfister's _In Search of
Clusters_) the affinity is the CPU on which it would be preferred to
give a particular process its next quantum. But if you've got two
CPU-intensive processes running on CPU0, and CPU1 is relatively free, a
scheduler using CPU affinity would move one of the processes from CPU0
to CPU1, and probably change its affinity as well (though perhaps not,
if it were a NUMA architecture).

cjs
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Curt Sampson       <cjs@example.com>        +81 90 7737 2974   
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