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From: Boqun Feng <boqun.feng@gmail.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	linux-kernel@vger.kernel.org,
	Andrea Parri <parri.andrea@gmail.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	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>,
	Daniel Lustig <dlustig@nvidia.com>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-arch@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [RFC 0/3] tools/memory-model: Add litmus tests for atomic APIs
Date: Mon, 17 Feb 2020 09:27:34 +0800
Message-ID: <20200217012734.GB69864@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> (raw)
In-Reply-To: <Pine.LNX.4.44L0.2002161113320.30459-100000@netrider.rowland.org>

On Sun, Feb 16, 2020 at 11:16:50AM -0500, Alan Stern wrote:
> On Sun, 16 Feb 2020, Paul E. McKenney wrote:
> 
> > On Sun, Feb 16, 2020 at 01:43:45PM +0800, Boqun Feng wrote:
> > > On Sat, Feb 15, 2020 at 07:25:50AM -0800, Paul E. McKenney wrote:
> > > > On Fri, Feb 14, 2020 at 10:27:44AM -0500, Alan Stern wrote:
> > > > > On Fri, 14 Feb 2020, Boqun Feng wrote:
> > > > > 
> > > > > > A recent discussion raises up the requirement for having test cases for
> > > > > > atomic APIs:
> > > > > > 
> > > > > > 	https://lore.kernel.org/lkml/20200213085849.GL14897@hirez.programming.kicks-ass.net/
> > > > > > 
> > > > > > , and since we already have a way to generate a test module from a
> > > > > > litmus test with klitmus[1]. It makes sense that we add more litmus
> > > > > > tests for atomic APIs into memory-model.
> > > > > 
> > > > > It might be worth discussing this point a little more fully.  The 
> > > > > set of tests in tools/memory-model/litmus-tests/ is deliberately rather 
> > > > > limited.  Paul has a vastly more expansive set of litmus tests in a 
> > > > > GitHub repository, and I am doubtful about how many new tests we want 
> > > > > to keep in the kernel source.
> > > > 
> > > > Indeed, the current view is that the litmus tests in the kernel source
> > > > tree are intended to provide examples of C-litmus-test-language features
> > > > and functions, as opposed to exercising the full cross-product of
> > > > Linux-kernel synchronization primitives.
> > > > 
> > > > For a semi-reasonable subset of that cross-product, as Alan says, please
> > > > see https://github.com/paulmckrcu/litmus.
> > > > 
> > > > For a list of the Linux-kernel synchronization primitives currently
> > > > supported by LKMM, please see tools/memory-model/linux-kernel.def.
> > > > 
> > > 
> > > So how about I put those atomic API tests into a separate directory, say
> > > Documentation/atomic/ ?
> > > 
> > > The problem I want to solve here is that people (usually who implements
> > > the atomic APIs for new archs) may want some examples, which can help
> > > them understand the API requirements and test the implementation. And
> > > litmus tests are the perfect tool here (given that them can be
> > > translated to test modules with klitmus). And I personally really think
> > > this is something the LKMM group should maintain, that's why I put them
> > > in the tools/memory-model/litmus-tests/. But I'm OK if we end up
> > > deciding those should be put outside that directory.
> > 
> > Good point!
> > 
> > However, we should dicuss this with the proposed beneficiaries, namely
> > the architecture maintainers.  Do they want it?  If so, where would
> > they like it to be?  How should it be organized?
> > 

Paul,

Well, I was simply motivated by the discuss on microblaze's atomic
implementation (which I pasted the link in this cover letter):

	https://lore.kernel.org/lkml/20200213085849.GL14897@hirez.programming.kicks-ass.net/

, please see the last paragraph, Michal asking Peter for some tests. So
I think there is at least some one wanting this ;-)

> > In the meantime, I am more than happy to accept litmus tests into the
> > github archive.
> > 

Thanks ;-)

> > So how would you like to proceed?

I think we are still at the discussion stage, so I'm happy to see
suggestions on where to put the litmus tests and which litmus tests
should be included.

> 
> I think it makes sense to put Boqun's tests under Documentation/ rather
> than tools/.  After all, their point is to document the memory model's
> requirements for operations on atomic_t's.  They aren't meant to be
> examples or demos showing how to use herd or write litmus tests.
> 

Alan,

Got it. I will create the Documentation/atomic directory and put the
litmus tests there in the next version.

Thank you both!

Regards,
Boqun

> Alan
> 

      reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14  4:01 Boqun Feng
2020-02-14  4:01 ` [RFC 1/3] Documentation/locking/atomic: Fix atomic-set litmus test Boqun Feng
2020-02-14  4:01 ` [RFC 2/3] tools/memory-model: Add a litmus test for atomic_set() Boqun Feng
2020-02-14  8:12   ` Andrea Parri
2020-02-14 10:40     ` Boqun Feng
2020-02-25  7:34       ` Boqun Feng
2020-02-25 13:01         ` Luc Maranget
2020-02-26  2:51           ` Boqun Feng
2020-02-14 15:47   ` Alan Stern
2020-02-14 23:52     ` Boqun Feng
2020-02-17 11:02       ` Peter Zijlstra
2020-02-14  4:01 ` [RFC 3/3] tools/memory-model: Add litmus test for RMW + smp_mb__after_atomic() Boqun Feng
2020-02-14  6:15   ` Boqun Feng
2020-02-14  8:18     ` Andrea Parri
2020-02-14  8:20       ` Boqun Feng
2020-02-14 15:58   ` Alan Stern
2020-02-15  0:09     ` Boqun Feng
2020-02-14  9:55 ` [RFC 0/3] tools/memory-model: Add litmus tests for atomic APIs Peter Zijlstra
2020-02-14 10:20 ` Paul E. McKenney
2020-02-14 15:27 ` Alan Stern
2020-02-14 23:39   ` Boqun Feng
2020-02-15 15:25   ` Paul E. McKenney
2020-02-16  5:43     ` Boqun Feng
2020-02-16 12:06       ` Paul E. McKenney
2020-02-16 16:16         ` Alan Stern
2020-02-17  1:27           ` Boqun Feng [this message]

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