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SubjectRe: [PATCH RFC tools/memory-model] Add litmus-test naming scheme
On Tue, May 29, 2018 at 09:17:13PM +0100, Will Deacon wrote:
> On Tue, May 29, 2018 at 05:11:07AM -0700, Paul E. McKenney wrote:
> > On Tue, May 29, 2018 at 10:30:50AM +0100, Will Deacon wrote:
> > > Hi Paul,
> > >
> > > On Fri, May 25, 2018 at 12:10:20PM -0700, Paul E. McKenney wrote:
> > > > This commit documents the scheme used to generate the names for the
> > > > litmus tests.
> > > >
> > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > > > ---
> > > > README | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> > > > 1 file changed, 135 insertions(+), 1 deletion(-)
> > >
> > > Whilst I think documentation like this is extremely important for users,
> > > this feels like it's documenting how to drive parts of diy and I'm not
> > > convinced that it belongs in the kernel source tree as long as the projects
> > > remain separate.
> > >
> > > Why not contribute this to the herdtools7 documentation, then just reference
> > > that from here? That would also be helpful for other people interested in
> > > memory models, but perhaps not interested in Linux (assuming such people
> > > exist ;).
> >
> > We would still need at least a pointer from the Linux kernel to that
> > documentation, but I am happy either way. We probably need examples of
> > the common cases, but probably not a full exposition of all the available
> > herd7 edges.
>
> Completely agreed.
>
> > Should this be in the herdtools7 documentation, or as added detail
> > from a variation on the "diyone7 -bell linux-kernel.bell -show edges"
> > command? If the latter, I suppose that the ones coming from the .bell
> > file might simply be labelled as such.
>
> Many of the edges aren't specific to the Linux kernel, so I think they
> should be part of the diyone7 documentation. We could then describe only
> the additional edges added by the kernel memory model (e.g. "Once") in
> the kernel documentation.

And there are a -lot- of them, and they are likely to change going
forward, both in herd7 and in linux-kernel.bell. How about if I give
examples and say where they are from and how to get a list, as in the
following --squash commit to be merged with the orginal?

Thanx, Paul

------------------------------------------------------------------------

commit e366b8cd832535894c55265c112355c4de9a3247
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Wed Sep 5 15:38:00 2018 -0700

squash! EXP tools/memory-model: Add litmus-test naming scheme

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Apply feedback from Will Deacon. ]

diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index 08c1116c0314..5ee08f129094 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -243,56 +243,11 @@ produce the name:

Adding the ".litmus" suffix: SB+rfionceonce-poonceonces.litmus

+The descriptors that describe connections between consecutive accesses
+within the cycle through a given litmus test can be provided by the herd
+tool (Rfi, Po, Fre, and so on) or by the linux-kernel.bell file (Once,
+Release, Acquire, and so on).

-=======================
-LITMUS TEST DESCRIPTORS
-=======================
-
-These descriptors cover connections between consecutive accesses within
-the cycle through a given litmus test:
-
-Fre: From-read external. The current process wrote a variable that
- the previous process read. Example: The SB (store buffering) test.
-Fri: From-read internal. This process read a variable and then
- immediately wrote to it. Example: ???
-PodRR: Program-order different variable, read followed by read.
- This process read a variable and again read a different variable.
- Example: The read-side process in the MP (message-passing) test.
-PodRW: Program-order different variable, read followed by write.
- This process read a variable and then wrote a different variable.
- Example: The LB (load buffering) test.
-PodWR: Program-order different variable, write followed by read.
- This process wrote a variable and then read a different variable.
- Example: The SB (store buffering) test.
-PodWW: Program-order different variable, write followed by write.
- This process wrote a variable and again wrote a different variable.
- Example: The write-side process in the MP (message-passing) test.
-PosRR: Program-order same variable, read followed by read.
- This process read a variable and again read that same variable.
- Example: ???
-PosRW: Program-order same variable, read followed by write.
- This process read a variable and then wrote that same variable.
- Example: ???
-PosWR: Program-order same variable, write followed by read.
- This process wrote a variable and then read that same variable.
- Example: ???
-PosWW: Program-order same variable, write followed by write.
- This process wrote a variable and again wrote that same variable.
- Example: ???
-Rfe: Read-from external. The current process read a variable written
- by the previous process. Example: The MP (message passing) test.
-Rfi: Read-from internal. The current process wrote a variable and then
- immediately read the value back from it. For the purposes
- of litmus-test code generation, Rfi acts identically to PosWR.
- However, they differ for purposes of naming, and they also result
- in different "exists" clauses.
- Example: ???
-Wse: Write same external. The current process wrote to a variable that
- was also written to by the previous process. Example: ???
-Wsi: Write same internal. The current process wrote to a variable and
- then immediately wrote to it again. Example: ???
-
-Please note that the above is a partial list. To see the full list of
-descriptors, execute the following command:
+To see the full list of descriptors, execute the following command:

$ diyone7 -bell linux-kernel.bell -show edges
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