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Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?



>
>
>
>---- Original Message ----
>From: ron.l.johnson@cox.net
>To: debian-user@lists.debian.org
>Subject: Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?
>Date: Fri, 22 Oct 2010 12:44:39 -0500
>
>>On 10/22/2010 10:34 AM, owens@netptc.net wrote:
>>>>
>>>> ---- Original Message ----
>>>> From: ron.l.johnson@cox.net
>>>> To: debian-user@lists.debian.org
>>>> Subject: Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?
>>>> Date: Fri, 22 Oct 2010 02:00:45 -0500
>>>>
>>>>>
>>>>> Correct.  The amount of effort needed for cross-CPU
>communication,
>>>>> cache coherency and OS process coordination increases much more
>than
>>>>
>>>>> linearly as you add CPUs.
>>>
>>> In fact IIRC the additional overhead follows the square of the
>number
>>> of CPUs.
>>
Ron et al
See the following:
http://en.wikipedia.org/wiki/Amdahl's_law
Larry
>>Maybe in brute-force implementations, but otherwise the machine 
>>would bog down after just a few CPUs.
>>
>>Note that h/w engineers and OS designers/writers have put a lot of 
>>work into minimizing the overhead and maximize the parallelism of 
>>extra CPUs.
>>
>>-- 
>>Seek truth from facts.
>>
>>
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>>
>>



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