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Re: About Lockfree...

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On 10/7/2013 8:07 PM, aminer wrote:
> We have to be smart please, there are those that
> like Lockfree algorithms, but in my opinion those
> lockfree algorithms have an important weakness, in high contention
> scenarios they  will higher the cache-coherence traffic
> so they will slow the things, in worst scenarios you can
> have 1+2+3+4+ ..N = ((N^2+N)/2) or even worse N+N+N+N...N = N^2
> cache lines transfers from the memory


Those lockfree FIFO queue algorthms higher the cache-coherency traffic 
when there is contention, in worst scenarios you can
have 1+2+3+4+ ..N = ((N^2+N)/2) or even worse N+N+N+N...N = N^2
cache lines transfers from the memory and those Lockfree FIFO queue
algotithms are not FIFO fair , hence you can also have starvation with 
Lockfree FIFO queue algorithms, and this is not good at all,
so what i will advice is to wrap those push() and pop() of your FIFO 
queue with two Locks that supports FIFO fairness and that lower the 
cache-coherence traffic, this is better i think, so you can use for 
example the Scalable Anderson Lock , the scalable MCS Lock or my 
scalable distributed Lock for that , those Locks lower the 
cache-coherence traffic and are FIFO fair , so they avoid starvation and
are better for realtime systems.




Amine Moulay Ramdane.

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About Lockfree... aminer <aminer@toto.net> - 2013-10-07 20:07 -0700
  Re: About Lockfree... aminer <aminer@toto.net> - 2013-10-07 20:14 -0700
  Re: About Lockfree... aminer <aminer@toto.net> - 2013-10-07 20:35 -0700

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