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From: John Baldwin <jhb@freebsd.org>
To: Andriy Gapon <avg@freebsd.org>
Date: Tue, 17 May 2011 11:51:17 -0400
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Cc: Max Laier <max@love2party.net>,
	FreeBSD current <freebsd-current@freebsd.org>, neel@freebsd.org,
	Peter Grehan <grehan@freebsd.org>
Subject: Re: proposed smp_rendezvous change
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On Tuesday, May 17, 2011 10:34:41 am Andriy Gapon wrote:
> on 17/05/2011 16:58 John Baldwin said the following:
> > No, it doesn't quite work that way.  It wouldn't work on Alpha for example.
> > 
> > All load_acq is a load with a memory barrier to order other loads after it.
> > It is still free to load stale data.  Only a read-modify-write operation
> > would actually block until it could access an up-to-date value.
> 
> Hmm, ok.
> How about atomic_add_acq_int(&smp_rv_waiters[0], 0) ? :-)
> Or an equivalent MI action that doesn't actually change smp_rv_waiters[0] value,
> if there could be any.
> Maybe explicit atomic_cmpset_acq_int(&smp_rv_waiters[0], 0, 0) ?
> 
> You see at what I am getting?

Yeah, either of those would work.  At this point just leaving the
atomic_add_int() as-is would be the smallest diff. :)

-- 
John Baldwin