On Wed, 9 Jan 2019 at 12:17, Martin Truebner <[email protected]> wrote:

> Joe,
>
> Robs is answer is already saying everything.... but let me give you
> some more details.
>
> the load (or store) will always do it on a fullword....BUT to do it
> proper would require doing it with a CS.
>

As long as the operand is properly aligned...


> MVC might on some CPUs appear to do it 4 byte wise (or other multiples
> thereof) -
>
> And again the question: why not do it proper in a code-segment
> that is fully aware of the multi-CPU environment.
>

The CPU cache is the other motivation to stay away from heavy use of shared
variables but keep things per CPU with a low-frequency distribution
process. When you keep the per-CPU objects  far enough apart, you avoid
frequent invalidating cache lines on the sibling CPU.

Rob

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