From: Paolo Bonzini <pbonzini@redhat.com>
To: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
Alan Stern <stern@rowland.harvard.edu>,
Andrea Parri <parri.andrea@gmail.com>,
Will Deacon <will.deacon@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
David Howells <dhowells@redhat.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Luc Maranget <luc.maranget@inria.fr>,
Akira Yokosawa <akiyks@gmail.com>
Subject: Re: [PATCH] memory-model: fix cheat sheet typo
Date: Thu, 12 Apr 2018 12:18:13 +0200 [thread overview]
Message-ID: <eda463d8-aa4e-2e6b-9d1d-41a5a4eaa3a7@redhat.com> (raw)
In-Reply-To: <20180412092303.GA6044@andrea>
On 12/04/2018 11:23, Andrea Parri wrote:
>>
>> - smp_store_mb() is missing
>
> Good point. In fact, we could add this to the model as well:
> following Peter's remark/the generic implementation,
Good idea. smp_store_mb() can save some clock cycles in the relatively
common idiom
write a write b
read b read a
if (b) if (a)
wake 'em we've been woken
> Yeah, those 'Ordering is cumulative', 'Ordering propagates' could
> mean different things to different readers... IMO, we may even omit
> such information; this doc. does not certainly aim for completeness,
> after all. OTOH, we ought to refrain from making this doc. an excuse
> to transform (what it is really) high-school maths into some black
> magic.
FWIW, what I miss in explanation.txt (and to some extent in the paper)
is a clear pointer to litmus tests that rely on cumulativity and
propagation. In the meanwhile I'll send some patches. Thanks for the
feedback, as it also helps validating my understanding of the model.
Thanks,
Paolo
next prev parent reply other threads:[~2018-04-12 10:18 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-09 16:50 [PATCH] memory-model: fix cheat sheet typo Paolo Bonzini
2018-04-09 18:42 ` Paul E. McKenney
2018-04-10 20:32 ` Paul E. McKenney
2018-04-10 21:10 ` Paolo Bonzini
2018-04-10 21:34 ` Paul E. McKenney
2018-04-11 11:15 ` Paolo Bonzini
2018-04-11 16:19 ` Paul E. McKenney
2018-04-11 16:31 ` Peter Zijlstra
2018-04-11 17:06 ` Paolo Bonzini
2018-04-12 12:52 ` Boqun Feng
2018-04-12 9:23 ` Andrea Parri
2018-04-12 10:18 ` Paolo Bonzini [this message]
2018-04-12 11:21 ` Andrea Parri
2018-04-12 21:18 ` Paul E. McKenney
2018-04-13 9:54 ` Andrea Parri
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