lkml.org 
[lkml]   [2018]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC tools/memory-model] Add litmus-test naming scheme
On Wed, Sep 05, 2018 at 05:01:17PM -0700, Paul E. McKenney wrote:
> 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?

Sure, that looks much easier to maintain. With that, you can add my ack:

Acked-by: Will Deacon <will.deacon@arm.com>

Cheers,

Will

> ------------------------------------------------------------------------
>
> 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
>

\
 
 \ /
  Last update: 2018-09-06 15:53    [W:0.072 / U:4.400 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site