From: Matt Hurd (matt.hurd_at_[hidden])
Date: 2004-09-20 06:08:31
>Peter Dimov <pdimov_at_[hidden]> wrote:
> > Matt Hurd wrote:
> > I'm interested in getting something like "needs_lock" below into the
> > normal traits, perhaps as part of boost thread. It informs you
> > whether of not an operation on such a contiguous block needs a lock to
> > be atomic.
> > For example, on ia32 32 bit aligned ops are atomic, on ia64 it is 64
> > bit. doubles on ia32 need locking to be atomic, on ia64 they don't.
> What do you mean by "atomic"? Do you expect the change to the value to be
> visible to other threads?
Just memory consistent / atomic. That is, if you write to memory or
read from memory all the bits will be guaranteed to make it as an
indivisible unit. It doesn't say anything about the timing of the
visibility or ordering w.r.t. like memory transactions.
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