Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] doc: Update wake_up() & co. memory-barrier guarantees | Date | Mon, 25 Jun 2018 13:12:45 +0100 |
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Peter Zijlstra <peterz@infradead.org> wrote:
> So yes, I suppose we're entirely suck with the full memory barrier > semantics like that. But I still find it easier to think of it like a > RELEASE that pairs with the ACQUIRE of waking up, such that the task > is guaranteed to observe it's own wake condition. > > And maybe that is the thing I'm missing here. These comments only state > that it does in fact imply a full memory barrier, but do not explain > why, should it?
I think because RELEASE and ACQUIRE concepts didn't really exist in Linux at the time I wrote the doc, so the choices were read/readdep, write or full.
Since this document defines the *minimum* you can expect rather than what the kernel actually gives you, I think it probably makes sense to switch to RELEASE and ACQUIRE here.
David
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