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Re: Cache-coherence traffic 1...

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Hello,

If you want to understand my scalable distributed fair Lock,
read this:

http://pages.videotron.com/aminer/DLOCK.html

I have just added a Ticket mechanism to the algorithm so that
it becomes fair.


Thank you,
Amine Moulay Ramdane.



On 10/11/2013 11:21 AM, aminer wrote:
> I correct some typos...
>
> Hello,
>
> I have come to an interresting subject, in computer science
> we calculate the complexity to give an idea at how good
> or bad is the algorithm, it's the same with Locks you have
> to do some calculations with Locks algorithms to give an idea at how
> good or bad the Lock is with cache-coherence traffic, so follow with me
> please, if you take a look at the source code of my
> scalable distributed fair Lock (you can download the source
> code at:  http://pages.videotron.com/aminer/)
>
> You will read inside the LW_DFLOCK.pas right on the
> "procedure TDFLOCK.Enter;" you will read this:
>
> ==
>
> if ((FCount3^.FCount3=2) and CAS(FCount2.FCount2,1,0))
> then
> begin
>   myobj^.myid:=-1;
>   break;
> end;"
>
> ==
>
> If you have noticed if FCount2.FCount2 have changed this
> will generate N  (N is the number of threads) cache lines misses
> and cache lines transfers, but you have to be smart please ,
> in a contention scenario since we are looping around:
>
> "if ((FCount3^.FCount3=2) and (FCount1^[myid].FCount1=myobj^.count))
> then break;"
>
> and
>
> FCount1^[myid].FCount1 is on the a local cache
>
> that means that the cache-coherence traffic will be reduced to 1
> cache misse and 1 cache line tranfer every time  FCount1^[myid].FCount1
> have changed , so this is better than
> the cache-coherence traffic of 1+2+3...N = (N^2+N)/2 or even worse the
> N+N+N+...N of the spinlock with a backoff or the Ticket spinlock,
> other than that my scalable distributed Lock is Fair and it avoids
> starvation.
>
>
>
>
> Thank you,
> Amine Moulay Ramdane.
>
>
>
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Cache-coherence traffic 1... aminer <aminer@toto.net> - 2013-10-11 11:21 -0700
  Re: Cache-coherence traffic 1... aminer <aminer@toto.net> - 2013-10-11 11:29 -0700

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