Date: Thu, 24 May 2012 17:04:33 -0700 From: Marcel Moolenaar <marcel@xcllnt.net> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, Marcel Moolenaar <marcel@freebsd.org>, src-committers@freebsd.org Subject: Re: svn commit: r235931 - head/sys/powerpc/include Message-ID: <B04831EF-C423-48C6-AFA6-F8FD07AFA1A2@xcllnt.net> In-Reply-To: <4FBEBA30.6050901@freebsd.org> References: <201205242045.q4OKjipb059398@svn.freebsd.org> <4FBEA493.4020702@freebsd.org> <EEFFC9C4-7469-4D70-A5C6-7F5CB19CAC28@xcllnt.net> <4FBEB2F3.4060405@freebsd.org> <358A54BA-6B8E-4685-8CDD-CCAC305ACA2B@xcllnt.net> <4FBEBA30.6050901@freebsd.org>
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On May 24, 2012, at 3:46 PM, Nathan Whitehorn wrote: > On 05/24/12 17:22, Marcel Moolenaar wrote: >>=20 >> On May 24, 2012, at 3:15 PM, Nathan Whitehorn wrote: >>=20 >>>>> Summary: >>>>> 1. *mb() must be lwsync or sync on all machines, except for wmb() = which could be eieio >>>>> 2. __ATOMIC_ACQ() must be isync (though could be reduced to lwsync = with bus_space changes) >>>>> 3. __ATOMIC_REL() must be lwsync or sync >>>>=20 >>>> This is absolutely not what I concluded from our discussions. I = have no idea >>>> how we could end up so out of sync... >>>>=20 >>>=20 >>> Thanks for the quick change. No idea how we got out of sync. I find = all of this synchronization stuff a little mind-bending, so sorry for = any miscommunication. __ATOMIC_ACQ() needed to also be isync on ppc64, = so I've fixed that up. Things should be good now. >>=20 >> Ok. I didn't change wmb() to eieio as I wanted to avoid a pendulum = effect. >> I'll reread our emails and make sure wmb() is what we think it is and = if >> so I'll do a followup commit. >> FYI, >>=20 >=20 > I don't think it really makes a difference. Basically nothing uses = wmb(), and those things that do mostly use it wrong and need sync. So it = should probably stay as [lw]sync. Works for me. Thanks! --=20 Marcel Moolenaar marcel@xcllnt.net
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