On Sat, Aug 23, 2014 at 11:01:01AM -0700, Randy Dunlap wrote: > On 08/22/14 23:05, Ganesh Rapolu wrote: > > In the first example in the memory-barriers.txt file, CPU 2 is assigned to > > run (x = B; y = A;). However, the rest of the example proceeds as if CPU 2 had been > > running (x = A; y = B;) as shown by the descriptions of the possible executions: > > > > STORE A=3, STORE B=4, x=LOAD A->3, y=LOAD B->4 > > STORE A=3, STORE B=4, y=LOAD B->4, x=LOAD A->3 > > STORE A=3, x=LOAD A->3, STORE B=4, y=LOAD B->4 > > STORE A=3, x=LOAD A->3, y=LOAD B->2, STORE B=4 > > STORE A=3, y=LOAD B->2, STORE B=4, x=LOAD A->3 > > STORE A=3, y=LOAD B->2, x=LOAD A->3, STORE B=4 > > STORE B=4, STORE A=3, x=LOAD A->3, y=LOAD B->4 > > STORE B=4, ... > > ... > > > > The change was merely to make the inital evironment consistent with what happens in the > > rest of the example. > > > > Signed-off-by: Ganesh Rapolu <ganesh.rapolu@xxxxxxxxxxx> > > > Comments David, Alexey, Andrew, Paul? > > This would revert Alexey's patch 615cc2c9cf9529846fbc342560d6787c2ccaaeea: > "Documentation/memory-barriers.txt: fix important typo re memory barriers" > that was merged on June 6, 2014. > > Thanks. > > > > --- > > Documentation/memory-barriers.txt | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt > > index a4de88f..9a46bbe 100644 > > --- a/Documentation/memory-barriers.txt > > +++ b/Documentation/memory-barriers.txt > > @@ -115,8 +115,8 @@ For example, consider the following sequence of events: > > CPU 1 CPU 2 > > =============== =============== > > { A == 1; B == 2 } > > - A = 3; x = B; > > - B = 4; y = A; > > + A = 3; x = A; > > + B = 4; y = B; Alexey's patch was correct as far as it went, but it was incomplete. (Read his commit log for more information.) Would either of you like to send a patch fixing up the combinations? Thanx, Paul > > The set of accesses as seen by the memory system in the middle can be arranged > > in 24 different combinations: > > > > > -- > ~Randy > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html