[Eug-lug] Concurrency, (free lunch is over article)

[John Sechrest]

If you look at the architecture of the old Sequent systems, 
they were able to get linear, or near linear speedup on 
systems up to 32 processors. They did it with a lot of cache magic.
But they had a way that straight applications could win in this environment.

I think that we generally do not do big programs in this context. We do lots
of little things. In this way, multiple cores are a big win, assuming that
do the right cache magic.





Mike Cherba <mike.cherba at caviumnetworks.com> writes:

 % Just finished reading the article.  In my mind the question really
 % becomes a matter of provisioning multiple processors to the best
 % effect.  I've not played with the SMP portions of the Linux kernel as
 % I've not had a multiproc box to run it with.  However, this is an area
 % of real concern for me as newer generations of the network processors I
 % work with will have up to 16 cores within a single chip.  
 % 
 % I find it interesting that the article only covers one percieved facet
 % of mutlicore performance and doesn't really cover effective division of
 % work as the number of processors goes toward infinity.  While SMP is a
 % good approach for 2 or even 4 processors, I do not believe it to be the
 % best approach for numbers of cores higher than that.  Especially
 % depending on the work to be done.  Once you have more than a few cores,
 % you can afford to specialize the tasks of each core at an even lower
 % level.  Certain functions work best with a single CPU focused on them.  
 % 
 % My concerns are that most software developers today do not understand
 % how to design applications which effectively make use of multiple
 % processing units.  
 % 
 % Just my $.02 !
 % 		-Mike
 % 
 % -- 
 % "The meek shall inherit the Earth. The rest of us are getting the hell
 % off this rock!"
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John Sechrest          .         Helping people use
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