Messages in this thread |  | | Date | Wed, 18 Feb 2015 17:32:56 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] [PATCH] sched: Add smp_rmb() in task rq locking cycles |
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On 02/18, Peter Zijlstra wrote: > > On Wed, Feb 18, 2015 at 04:53:34PM +0100, Oleg Nesterov wrote: > > On 02/17, Paul E. McKenney wrote: > > > > > > | mb | wmb | rmb | rbd | acq | rel | ctl | > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > mb | Y | | Y | y | Y | | Y + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > wmb | Y | | Y | y | Y | | Y + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > rmb | | | | | | | + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > rbd | | | | | | | + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > acq | | | | | | | + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > rel | Y | | Y | y | Y | | Y + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > ctl | | | | | | | + > > > -----+-------+-------+-------+-------+-------+-------+-------+ > > > > OK, so "acq" can't pair with "acq", and I am not sure I understand. > > Please consider the table in the context of message passing; that is > what Paul proposed. Your example from sysvsems, while interesting, would > not fit the general scenario of message passing.
Ah, yeeees, sorry. Somehow I completely missed that part of Paul's email.
> This too illustrates a problem with that approach, people can't read, so > they'll pick the wrong table to look at.
At least we know that I certainly can't ;)
Thanks,
Oleg.
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