Messages in this thread | | | Date | Tue, 6 Oct 2015 18:06:50 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] Documentation: Remove misleading examples of the barriers in wake_*() |
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On Thu, Sep 24, 2015 at 09:21:22PM +0800, Boqun Feng wrote: > > Included in it are some of the details on this subject, because a wakeup > > has two prior states that are of importance, the tasks own prior state > > and the wakeup state, both should be considered in the 'program order' > > flow. > > > > Great and very helpful ;-) > > > So maybe we can reduce the description in memory-barriers to this > > 'split' program order guarantee, where a woken task must observe both > > its own prior state and its wakee state. > ^^^^^ > I think you mean "waker" here, right?
Yes.
> And the waker is not necessarily the same task who set the @cond to > true, right?
It should be.
> If so, I feel like it's really hard to *use* this 'split' > program order guarantee in other places than sleep/wakeup itself. Could > you give an example? Thank you.
It was not meant to be used in any other scenario; the 'split' PO really is part of the whole sleep/wakeup. It does not apply to anything else.
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