Grokking concurrency, message passing and Co

[div0]

On 11/07/2010 20:00, BCS wrote:
> Hello div0,
>
>> The rule of thumb is don't bother spawning more threads than you have
>> cpus. You're just wasting resources mostly.
>>
>
> You REALLY don't want more threads trying to run than you have cores.
> Threads in a wait state, are less of an issue, but they still use up
> resources.
>

I think you're going a bit far there.

How many h/w threads does a core support?
1, 2, 4 or even 8 today (on power 7 machines).

And tomorrow?

You can only use basic rules of thumb with multi threading unless you 
are going to spend time and effort profiling your application on a 
specific machine or do some kind of run time profiling & configuration.

-- 
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