On Thu, 2015-07-16 at 19:49 +0200, Peter Zijlstra wrote:
> On Thu, Jul 16, 2015 at 12:22:40PM -0500, Tom Zanussi wrote:
> > + for (i = 0; i < elt->map->n_fields; i++) {
> > + atomic64_set(&dup_elt->fields[i].sum,
> > + atomic64_read(&elt->fields[i].sum));
> > + dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
> > + }
> > +
> > + return dup_elt;
> > +}
>
> So there is a lot of atomic64_{set,read}() in this patch set, what kind
> of magic properties do you assume they have?
>
> Note that atomic*_{set,read}() are weaker than {WRITE,READ}_ONCE(), so
> if you're assuming they do that, you're mistaken -- although it is on a
> TODO list someplace to go fix that.
Not assuming any magic properties - I just need an atomic 64-bit counter
for the sums and that's the API for setting/reading those. When reading
a live trace the exact sum you get is kind of arbitrary..
Tom
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