4 cores and 8 threads

[Keith Smith]

Thank you to everyone who replied!!  Very informative.


On 2016-09-07 22:19, Michael Butash wrote:
> This is a common recommendation really with hpc applications,
> particularly when doing higher-bandwidth operations, such as
> networking at 10-100gb interfaces. Hyperthreading arbitrator in the
> kernel is like a buffer, the L1-2 cache (I think), that fills as the
> cpu backs up.  When full, the arbitrator can't pass to the cpu, sits
> in buffer, and eventually gets there (hopefully).  This is BAD when
> you are doing very latency sensitive crunching.
> 
> Likewise, things like irq balancing are generally disabled for the
> same reason to keep hardware like ethernet and drive hba's stable and
> low-latency.  You try to design to the cpu workload, memory, pci
> bandwidth, ethernet hardware, etc, to not *need* buffers, at least
> when a dev understands such things, which is generally few and far
> between.
> 
> -mb
> 
> 
> On 09/07/2016 01:27 PM, Kevin Fries wrote:
>> 
>> I once worked for a company doing ground water modeling for mining 
>> operations.  The program did a large series of fourier transformation 
>> to model the water levels over time... No Hyperthreading!!!
>> 
>> Most web servers, mail servers, database servers (depending on your 
>> number of indexes), are perfectly fine with hyperthreading turned on.
>> 
>> Kevin
>> 
> 
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-- 
Keith Smith