Messages in this thread | | | Subject | Re: [PATCH] memory-model: fix cheat sheet typo | From | Paolo Bonzini <> | Date | Tue, 10 Apr 2018 23:10:06 +0200 |
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On 10/04/2018 22:32, Paul E. McKenney wrote: > On Mon, Apr 09, 2018 at 11:42:58AM -0700, Paul E. McKenney wrote: >> On Mon, Apr 09, 2018 at 06:50:15PM +0200, Paolo Bonzini wrote: >>> "RWM" should be "RMW", and that's more or less the extent to which I >>> can claim to change the document. :) In particular, "Self" is not >>> documented and the difference between "Self" and "SV" is not clear >>> to me. >>> >>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> >> >> Applied, though without the questions. ;-) >> >> "Self" is for things like smp_load_acquire() and smp_store_release() >> that order themselves against later and earlier accesses, respectively. >> This ordering applies to later/earlier access to all variables, not >> just the one that smp_load_acquire()/smp_store_release() accessed. >> In contrast, things like smp_mb() order only other accesses, not >> themselves. Or at least it is impossible to proves whether or not they >> order themselves because they are not separately visible to other CPUs. >> >> "SV" is "same variable", which applies to pretty much anything that >> accesses a variable, but not to things like smp_mb() which do not. >> >> Does that help? > > On the perhaps naive assumption that silence means assent, how about > the following patch?
Silence meant "I tried thinking of a patch myself, and hadn't come up yet with a fully satisfactory one"; that's some kind of assent I guess. :)
Your patch is certainly an improvement!
Thanks,
Paolo
> Thanx, Paul > > ------------------------------------------------------------------------ > > commit 818e46e8db6cacb099b8640b7f2945a3151c00ab > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Date: Tue Apr 10 13:24:19 2018 -0700 > > tools/memory-order: Improve key for SELF and SV > > The key for "SELF" was missing completely and the key for "SV" was > a bit obtuse. This commit therefore adds a key for "SELF" and improves > the one for "SV". > > Reported-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > diff --git a/tools/memory-model/Documentation/cheatsheet.txt b/tools/memory-model/Documentation/cheatsheet.txt > index c0eafdaddfa4..d502993ac7d2 100644 > --- a/tools/memory-model/Documentation/cheatsheet.txt > +++ b/tools/memory-model/Documentation/cheatsheet.txt > @@ -26,4 +26,5 @@ Key: C: Ordering is cumulative > DR: Dependent read (address dependency) > DW: Dependent write (address, data, or control dependency) > RMW: Atomic read-modify-write operation > - SV Same-variable access > + SELF: Orders self, as opposed to accesses both before and after > + SV: Orders later accesses to the same variable >
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