Hi,
On Sat, Sep 14, 2019 at 8:28 PM Vitaly Davidovich wrote:
>
> Unlike C++, where you can specify mem ordering for failure and success
> separately, Java doesn’t allow that. But, the mem ordering is the same for
> failure/success there. Unfortunately it doesn’t look like the javadocs
>
On x86, I’ve never heard of failed CAS being cheaper. In theory, cache
snooping can inform the core whether it’s xchg would succeed without going
through the RFO dance. But, to perform the actual xchg it would need
ownership regardless (if not already owned/exclusive).
Sharing ordinary mutable
Although not mentioned (neither on Doug's cookbook) I have always supposed was
more likely the c++ default for both weak/strong CAS ie seq_cst memory ordering.
To make this question more mechanical sympathy focused: on hardware level what
happen? I would be curious to know both x86/arm versions
