Understanding a false sharing example

Asked Jul 22 '17 at 16:25

Active Jul 22 '17 at 16:25

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I am studying false sharing and I have an example on how to avoid it by padding arrays:

Just making sure I understand correctly, this would only work if we're using 8 byte integers, right? If we're using 4 byte integers, the whole array would be 64 bytes and it wouldn't avoid false sharing.

asked Jul 22 '17 at 16:25

devil0150

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sum looks to be a 2d array of doubles, not int. sizeof(double) is at least 8 I believe – Ryan Stout Jul 22 '17 at 16:37
note that https://stackoverflow.com/questions/25524355/what-is-the-size-of-float-and-double-in-c-and-c says the size of a double isn't guaranteed, but on systems I've worked on doubles were always 8 bytes – Ryan Stout Jul 22 '17 at 16:40
oh, I apparently didn't notice the double. Thanks – devil0150 Jul 22 '17 at 17:12
should I just point that out in an answer? – Ryan Stout Jul 22 '17 at 17:19
@RyanStout yes sure – devil0150 Jul 22 '17 at 18:05

Understanding a false sharing example

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