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Re: False sharing

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>
> I did another experiment where I have two arrays that the threads
> write so that it can't combine the writes.

I think you may be wrong again, sorry. 10*sizeof long is 40 bytes.
If they lie in the same cache line, they will be combined. Maybe
RFO will be done sooner; or more likely, didn't you put the k array
on the cache boundary (or one of those arrays)?

OTOH, maybe you are right, 10 dependencies might be harder to keep
track of than one.

According to the Fine Manual, Core Duo has I think 6 Write Combining
buffers on L1D, of which at least 4 can be used a lot. That means,
not more than four arrays (in separate cache lines of course)
should be put in the loop: you have one.

> for(long i =0; i<  1000L * 1000L * 1000L; i++) {
>      for(long k = 0; k<  10; ++k ){
>        work[k] = k + i;
>      }
>    }
> Now finally I can see the effect if the buffer is separating the
> arrays:

I believe that part, I am not sure about the interpretation.

And, what are you exactly trying to do? Why not just do the 
synchronisation?

Edek

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Thread

False sharing curious <curious.oskar58@gmail.com> - 2011-05-30 04:26 -0700
  Re: False sharing Edek <edek.pienkowski@gmail.com> - 2011-05-30 22:29 +0200
    Re: False sharing curious <curious.oskar58@gmail.com> - 2011-05-31 03:21 -0700
      Re: False sharing Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-05-31 15:41 +0200
        Re: False sharing curious <curious.oskar58@gmail.com> - 2011-05-31 10:18 -0700
        Re: False sharing Edek <edek.pienkowski@gmail.com> - 2011-05-31 20:10 +0200
      Re: False sharing Edek <edek.pienkowski@gmail.com> - 2011-05-31 20:37 +0200
        Re: False sharing Edek <edek.pienkowski@gmail.com> - 2011-05-31 21:18 +0200
          Re: False sharing curious <curious.oskar58@gmail.com> - 2011-05-31 14:40 -0700
            Re: False sharing "Balog Pal" <pasa@lib.hu> - 2011-06-01 03:17 +0200
            Re: False sharing Edek <edek.pienkowski@gmail.com> - 2011-06-01 22:20 +0200
        Re: False sharing curious <curious.oskar58@gmail.com> - 2011-05-31 14:29 -0700
  Re: False sharing David Schwartz <davids@webmaster.com> - 2011-05-31 14:12 -0700
  Re: False sharing "Chris M. Thomasson" <cristom@charter.net> - 2011-06-11 15:34 -0700
    Re: False sharing "Chris M. Thomasson" <cristom@charter.net> - 2011-06-11 19:56 -0700
      Re: False sharing "Chris M. Thomasson" <cristom@charter.net> - 2011-06-11 21:07 -0700

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