Matthew Rosewarne on 16 Jun 2007 18:41:41 -0000


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Re: [PLUG] Use of dual core


On Saturday 16 June 2007, Antony P Joseph wrote:
> I just listed the available governors. "Performance" is governors which
> always sets frequency to the maximum.

This governor is for systems that don't have continuous scaling, but instead 
only a fixed set of speeds (usually two), such as my P3.  The "performance" 
governor is the counterpart of the "powersave" governor, which always sets 
the frequency to the minimum.  Newer CPUs that support dynamic continuous 
scaling do not need such crude governors and are much better off using an 
intelligent governor such as "ondemand" instead of "performance".  On 
battery, "conservative" is generally used, which actually does sacrifice some 
performance.

> This feature looks like "hack" in "synchronous processors" to achieve
> the power efficiency of "asynchronous processsors" by sacrificing
> performance.

Well, regardless of whether it's a hack or not, it does work and is a far 
better approach than leaving the processor running at full speed even when it 
isn't doing anything, which is why all modern CPUs do it.  Seriously, did I 
not make it clear that there _isn't_ a performance hit already?  I don't wish 
to be rude, but if you reply to someones message, do give them the bare 
minimum courtesy by at least reading it first.

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