On Sun, Jul 28, 2019 at 11:35:44AM -0400, Joel Fernandes wrote: [...] > > > > > +load of y (rfe link), P2's smp_store_release() ensures that P2's load > > > > > +of y executes before P2's store to z (second fence), which implies > > > > > that > > > > > +that stores to x and y propagate to P2 before the > > > > > smp_store_release(), which > > > > > +means that P2's smp_store_release() will propagate stores to x and y > > > > > to all > > > > > +CPUs before the store to z propagates (A-cumulative property of this > > > > > fence). > > > > > +Finally P0's load of z executes after P2's store to z has propagated > > > > > to > > > > > +P0 (rfe link). > > > > > > > > Again, a better change would be simply to replace the two instances of > > > > "fence" in the original text with "cumul-fence". > > > > > > Ok that's fine. But I still feel the rfe is not a part of the cumul-fence. > > > The fences have nothing to do with the rfe. Or, I am missing something > > > quite > > > badly. > > > > > > Boqun, did you understand what Alan is saying? > > > > > > > I think 'cumul-fence' that Alan mentioned is not a fence, but a > > relation, which could be the result of combining a rfe relation and a > > A-cumulative fence relation. Please see the section "PROPAGATION ORDER > > RELATION: cumul-fence" or the definition of cumul-fence in > > linux-kernel.cat. > > > > Did I get you right, Alan? If so, your suggestion is indeed a better > > change. > > To be frank, I don't think it is better if that's what Alan meant. It is > better to be explicit about the ->rfe so that the reader walking through the > example can clearly see the ordering and make sense of it. > > Just saying 'cumul-fence' and then hoping the reader sees the light is quite > a big assumption and makes the document less readable. >
After a bit more rereading of the document, I still think Alan's way is
better ;-)
Please consider the context of paragraph, this is an explanation of an
example, which is about the previous sentence:
The formal definition of the prop relation involves a coe or
fre link, followed by an arbitrary number of cumul-fence links,
ending with an rfe link.
, so using "cumul-fence" actually matches the definition of ->prop.
For the ease of readers, I can think of two ways:
1. Add a backwards reference to cumul-fence section here, right
before using its name.
2. Use "->cumul-fence" notation rather than "cumul-fence" here,
i.e. add an arrow "->" before the name to call it out that name
"cumul-fence" here stands for links/relations rather than a
fence/barrier. Maybe it's better to convert all references to
links/relations to the "->" notations in the whole doc.
Thoughts?
Regards,
Boqun
> I mean the fact that you are asking Alan for clarification, means that it is
> not that obvious ;)
>
> thanks,
>
> - Joel
>
>
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