* Paolo Bonzini (pbonz...@redhat.com) wrote: > > > On 30/03/2015 19:04, Dr. David Alan Gilbert wrote: > >>> > > That one's a trickier question. Compilers are absolutely capable > >>> > > of optimizing that far, *but* the C rules about when it's allowed > >>> > > to assume in-memory values remain unchanged are pretty > >>> > > conservative. I think any function call in the loop will require > >>> > > it to reload the value, for example. That said, a (compiler only) > >>> > > memory barrier might be appropriate to ensure that reload. > >> > > >> > That's exactly what atomic_read provides. > > So does that say I need the atomic_read but not the atomic_write - > > which seems a bit weird, but I think only due to the naming. > > No, you need both even though it's even more far-fetched that the > compiler will do something bad with the set.
OK, done - it's back to where it was with atomic_set/atomic_read. Dave > > Paolo -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
