From: Boqun Feng <boqun.feng@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <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>,
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 20:52:50 +0800 [thread overview]
Message-ID: <20180412125250.to46vdgztwa2jsbq@tardis> (raw)
In-Reply-To: <70348608-e695-1977-d34e-d7d66b07ad25@redhat.com>
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On Wed, Apr 11, 2018 at 07:06:36PM +0200, Paolo Bonzini wrote:
> On 11/04/2018 18:31, Peter Zijlstra wrote:
> >>> Prior Operation Subsequent Operation
> >>> --------------- ---------------------
> >>> R W RMW SV R W DR DW RMW SV
> >>> - - --- -- - - -- -- --- --
> >>> smp_store_mb() Y Y Y Y Y Y Y Y Y Y
> > I'm not sure about that, the generic version of that reads:
> >
> > include/asm-generic/barrier.h:#define __smp_store_mb(var, value)
> > do { WRITE_ONCE(var, value); __smp_mb(); } while (0)
> >
> > Which doesn't not have an smp_mb() before, so it doesn't actually order
> > prior; or I'm failing to read the table wrong.
>
> You're not, even better reason to document it. :) I was going from
> memory for the x86 version.
>
> I'll start tomorrow on fixes to the current document, while we discuss
> the split format and what to do about cumulativity and propagation.
>
Besides, since smp_store_mb() is a store, so there is no DR or DW for
the subsequent operations I think, because dependencies come from a read
rather than a write.
Regards,
Boqun
> Paolo
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next prev parent reply other threads:[~2018-04-12 12:48 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 [this message]
2018-04-12 9:23 ` Andrea Parri
2018-04-12 10:18 ` Paolo Bonzini
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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