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Re: pthread reader-writer mutex...

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On 6/14/2014 6:38 PM, Ramine wrote:
>
> Hello,
>
>
> Question:
>
>
> If you ask me a question such us why do we have to use
> such us your scalable RWLocks and not simply use
> pthread reader-writer lock ?
>


I correct my english typos:

If you ask me a question such as why do we have to use
such as your scalable RWLocks and not simply use
pthread reader-writer lock ?



>
> Answer:
>
> The Pthread reader-writer lock uses an expensive atomic operation
> on the reader side, so when a thread on the reader side executes this
> atomic operation it will generate a cache-line transfer between one core
> to the other, and this cache-line transfer is expensive, so each threads
> on the reader side of the Pthread reader-writer lock
> generates a cache-line transfer, so this will make the serial part
> of the Amdahl equation much bigger, so if you need to scale your
> Pthread reader-writer lock, the parallel part of the reader side
> must be much bigger than the time that it takes to transfer a cache-line
> between cores, so since Pthread reader-writer lock don't scale for
> reader sides that are for example smaller than the time that it takes to
> transfer a cache-line between one core to the other , this will make
> Pthread reader-writer not scalable, that not the same for my scalable
> RWLock, my scalable RWLocks scale much better than Pthread reader-writer
> lock even if the time under the reader side is equal or smaller than the
> time that it takes to tranfer a cache-line from one core to the other,
> and for bigger parallel part io have said that
> as you have noticed with me that to scale my scalable RWLocks
> you have to use a distributed memory configuration like in
> NUMA systems, and on the reader and writer part of my scalable RWLocks
> you have to use more expensive processing, that means you have
> to transfer data in parallel from the distributed memory to the CPUs,
> cause this memory transfers from distributed memory to
> the cores is more expensive than the cache-line transfers from one core
> to the other that i am generating inside my scalable RWLocks algorithms,
> so this will make the parallel part much bigger than the serial part so
> this will make my scalable RWLocks algorithms much more scalable, and
> this is good, that's the same for hardisks, you have to distribute your
> hardisks , and use multiple hardisks an access them in parallel,this
> also will make my scalable RWLocks  more scalable, and this is good.
>
> So as you have noticed my scalable RWLocks are still useful
> and good.
>
>
>
> Thank you,
> Amine Moulay Ramdane.
>

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pthread reader-writer mutex... Ramine <ramine@1.1> - 2014-06-14 18:38 -0700
  Re: pthread reader-writer mutex... Ramine <ramine@1.1> - 2014-06-14 18:54 -0700

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