* [PATCH v4] tools/memory-model: Document herd7 (abstract) representation
@ 2024-06-19 1:06 Andrea Parri
2024-06-20 17:12 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Andrea Parri @ 2024-06-19 1:06 UTC (permalink / raw)
To: stern, will, peterz, boqun.feng, npiggin, dhowells, j.alglave,
luc.maranget, paulmck, akiyks, dlustig, joel
Cc: linux-kernel, linux-arch, hernan.poncedeleon, jonas.oberhauser,
Andrea Parri
The Linux-kernel memory model (LKMM) source code and the herd7 tool are
closely linked in that the latter is responsible for (pre)processing
each C-like macro of a litmus test, and for providing the LKMM with a
set of events, or "representation", corresponding to the given macro.
This commit therefore provides herd-representation.txt to document
the representations of the concurrency macros, following their
"classification" in Documentation/atomic_t.txt.
Suggested-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
---
Changes since v3 [1]:
- note that rmw is a subset of po
- include paulmck's wordsmithing
- add limitations, aka stress that certain ops have been intentionally omitted
- add collected Reviewed-by: tags
Changes since v2 [2]:
- drop lk-rmw links
Changes since v1 [3]:
- add legenda/notations
- add some SRCU, locking macros
- update formatting of failure cases
- update README file
[1] https://lore.kernel.org/lkml/20240617201759.1670994-1-parri.andrea@gmail.com/
[2] https://lore.kernel.org/lkml/20240605134918.365579-1-parri.andrea@gmail.com/
[3] https://lore.kernel.org/lkml/20240524151356.236071-1-parri.andrea@gmail.com/
tools/memory-model/Documentation/README | 7 +-
.../Documentation/herd-representation.txt | 110 ++++++++++++++++++
2 files changed, 116 insertions(+), 1 deletion(-)
create mode 100644 tools/memory-model/Documentation/herd-representation.txt
diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index db90a26dbdf40..1f73014cc48a3 100644
--- a/tools/memory-model/Documentation/README
+++ b/tools/memory-model/Documentation/README
@@ -33,7 +33,8 @@ o You are familiar with Linux-kernel concurrency and the use of
o You are familiar with Linux-kernel concurrency and the use
of LKMM, and would like to learn about LKMM's requirements,
- rationale, and implementation: explanation.txt
+ rationale, and implementation: explanation.txt and
+ herd-representation.txt
o You are interested in the publications related to LKMM, including
hardware manuals, academic literature, standards-committee
@@ -57,6 +58,10 @@ control-dependencies.txt
explanation.txt
Detailed description of the memory model.
+herd-representation.txt
+ The (abstract) representation of the Linux-kernel concurrency
+ primitives in terms of events.
+
litmus-tests.txt
The format, features, capabilities, and limitations of the litmus
tests that LKMM can evaluate.
diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt
new file mode 100644
index 0000000000000..ed988906f2b71
--- /dev/null
+++ b/tools/memory-model/Documentation/herd-representation.txt
@@ -0,0 +1,110 @@
+#
+# Legend:
+# R, a Load event
+# W, a Store event
+# F, a Fence event
+# LKR, a Lock-Read event
+# LKW, a Lock-Write event
+# UL, an Unlock event
+# LF, a Lock-Fail event
+# RL, a Read-Locked event
+# RU, a Read-Unlocked event
+# R*, a Load event included in RMW
+# W*, a Store event included in RMW
+# SRCU, a Sleepable-Read-Copy-Update event
+#
+# po, a Program-Order link
+# rmw, a Read-Modify-Write link - every rmw link is a po link
+#
+# By convention, a blank line in a cell means "same as the preceding line".
+#
+# Disclaimer. The table includes representations of "add" and "and" operations;
+# corresponding/identical representations of "sub", "inc", "dec" and "or", "xor",
+# "andnot" operations are omitted.
+#
+ ------------------------------------------------------------------------------
+ | C macro | Events |
+ ------------------------------------------------------------------------------
+ | Non-RMW ops | |
+ ------------------------------------------------------------------------------
+ | READ_ONCE | R[once] |
+ | atomic_read | |
+ | WRITE_ONCE | W[once] |
+ | atomic_set | |
+ | smp_load_acquire | R[acquire] |
+ | atomic_read_acquire | |
+ | smp_store_release | W[release] |
+ | atomic_set_release | |
+ | smp_store_mb | W[once] ->po F[mb] |
+ | smp_mb | F[mb] |
+ | smp_rmb | F[rmb] |
+ | smp_wmb | F[wmb] |
+ | smp_mb__before_atomic | F[before-atomic] |
+ | smp_mb__after_atomic | F[after-atomic] |
+ | spin_unlock | UL |
+ | spin_is_locked | On success: RL |
+ | | On failure: RU |
+ | smp_mb__after_spinlock | F[after-spinlock] |
+ | smp_mb__after_unlock_lock | F[after-unlock-lock] |
+ | rcu_read_lock | F[rcu-lock] |
+ | rcu_read_unlock | F[rcu-unlock] |
+ | synchronize_rcu | F[sync-rcu] |
+ | rcu_dereference | R[once] |
+ | rcu_assign_pointer | W[release] |
+ | srcu_read_lock | R[srcu-lock] |
+ | srcu_down_read | |
+ | srcu_read_unlock | W[srcu-unlock] |
+ | srcu_up_read | |
+ | synchronize_srcu | SRCU[sync-srcu] |
+ | smp_mb__after_srcu_read_unlock | F[after-srcu-read-unlock] |
+ ------------------------------------------------------------------------------
+ | RMW ops w/o return value | |
+ ------------------------------------------------------------------------------
+ | atomic_add | R*[noreturn] ->rmw W*[once] |
+ | atomic_and | |
+ | spin_lock | LKR ->po LKW |
+ ------------------------------------------------------------------------------
+ | RMW ops w/ return value | |
+ ------------------------------------------------------------------------------
+ | atomic_add_return | F[mb] ->po R*[once] |
+ | | ->rmw W*[once] ->po F[mb] |
+ | atomic_fetch_add | |
+ | atomic_fetch_and | |
+ | atomic_xchg | |
+ | xchg | |
+ | atomic_add_negative | |
+ | atomic_add_return_relaxed | R*[once] ->rmw W*[once] |
+ | atomic_fetch_add_relaxed | |
+ | atomic_fetch_and_relaxed | |
+ | atomic_xchg_relaxed | |
+ | xchg_relaxed | |
+ | atomic_add_negative_relaxed | |
+ | atomic_add_return_acquire | R*[acquire] ->rmw W*[once] |
+ | atomic_fetch_add_acquire | |
+ | atomic_fetch_and_acquire | |
+ | atomic_xchg_acquire | |
+ | xchg_acquire | |
+ | atomic_add_negative_acquire | |
+ | atomic_add_return_release | R*[once] ->rmw W*[release] |
+ | atomic_fetch_add_release | |
+ | atomic_fetch_and_release | |
+ | atomic_xchg_release | |
+ | xchg_release | |
+ | atomic_add_negative_release | |
+ ------------------------------------------------------------------------------
+ | Conditional RMW ops | |
+ ------------------------------------------------------------------------------
+ | atomic_cmpxchg | On success: F[mb] ->po R*[once] |
+ | | ->rmw W*[once] ->po F[mb] |
+ | | On failure: R*[once] |
+ | cmpxchg | |
+ | atomic_add_unless | |
+ | atomic_cmpxchg_relaxed | On success: R*[once] ->rmw W*[once] |
+ | | On failure: R*[once] |
+ | atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[once] |
+ | | On failure: R*[once] |
+ | atomic_cmpxchg_release | On success: R*[once] ->rmw W*[release] |
+ | | On failure: R*[once] |
+ | spin_trylock | On success: LKR ->po LKW |
+ | | On failure: LF |
+ ------------------------------------------------------------------------------
--
2.34.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v4] tools/memory-model: Document herd7 (abstract) representation
2024-06-19 1:06 [PATCH v4] tools/memory-model: Document herd7 (abstract) representation Andrea Parri
@ 2024-06-20 17:12 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2024-06-20 17:12 UTC (permalink / raw)
To: Andrea Parri
Cc: stern, will, peterz, boqun.feng, npiggin, dhowells, j.alglave,
luc.maranget, akiyks, dlustig, joel, linux-kernel, linux-arch,
hernan.poncedeleon, jonas.oberhauser
On Wed, Jun 19, 2024 at 03:06:04AM +0200, Andrea Parri wrote:
> The Linux-kernel memory model (LKMM) source code and the herd7 tool are
> closely linked in that the latter is responsible for (pre)processing
> each C-like macro of a litmus test, and for providing the LKMM with a
> set of events, or "representation", corresponding to the given macro.
> This commit therefore provides herd-representation.txt to document
> the representations of the concurrency macros, following their
> "classification" in Documentation/atomic_t.txt.
>
> Suggested-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
> Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> Reviewed-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
I have reverted the previous version and queued this one, thank you!!!
Thanx, Paul
> ---
> Changes since v3 [1]:
> - note that rmw is a subset of po
> - include paulmck's wordsmithing
> - add limitations, aka stress that certain ops have been intentionally omitted
> - add collected Reviewed-by: tags
>
> Changes since v2 [2]:
> - drop lk-rmw links
>
> Changes since v1 [3]:
> - add legenda/notations
> - add some SRCU, locking macros
> - update formatting of failure cases
> - update README file
>
> [1] https://lore.kernel.org/lkml/20240617201759.1670994-1-parri.andrea@gmail.com/
> [2] https://lore.kernel.org/lkml/20240605134918.365579-1-parri.andrea@gmail.com/
> [3] https://lore.kernel.org/lkml/20240524151356.236071-1-parri.andrea@gmail.com/
>
> tools/memory-model/Documentation/README | 7 +-
> .../Documentation/herd-representation.txt | 110 ++++++++++++++++++
> 2 files changed, 116 insertions(+), 1 deletion(-)
> create mode 100644 tools/memory-model/Documentation/herd-representation.txt
>
> diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
> index db90a26dbdf40..1f73014cc48a3 100644
> --- a/tools/memory-model/Documentation/README
> +++ b/tools/memory-model/Documentation/README
> @@ -33,7 +33,8 @@ o You are familiar with Linux-kernel concurrency and the use of
>
> o You are familiar with Linux-kernel concurrency and the use
> of LKMM, and would like to learn about LKMM's requirements,
> - rationale, and implementation: explanation.txt
> + rationale, and implementation: explanation.txt and
> + herd-representation.txt
>
> o You are interested in the publications related to LKMM, including
> hardware manuals, academic literature, standards-committee
> @@ -57,6 +58,10 @@ control-dependencies.txt
> explanation.txt
> Detailed description of the memory model.
>
> +herd-representation.txt
> + The (abstract) representation of the Linux-kernel concurrency
> + primitives in terms of events.
> +
> litmus-tests.txt
> The format, features, capabilities, and limitations of the litmus
> tests that LKMM can evaluate.
> diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt
> new file mode 100644
> index 0000000000000..ed988906f2b71
> --- /dev/null
> +++ b/tools/memory-model/Documentation/herd-representation.txt
> @@ -0,0 +1,110 @@
> +#
> +# Legend:
> +# R, a Load event
> +# W, a Store event
> +# F, a Fence event
> +# LKR, a Lock-Read event
> +# LKW, a Lock-Write event
> +# UL, an Unlock event
> +# LF, a Lock-Fail event
> +# RL, a Read-Locked event
> +# RU, a Read-Unlocked event
> +# R*, a Load event included in RMW
> +# W*, a Store event included in RMW
> +# SRCU, a Sleepable-Read-Copy-Update event
> +#
> +# po, a Program-Order link
> +# rmw, a Read-Modify-Write link - every rmw link is a po link
> +#
> +# By convention, a blank line in a cell means "same as the preceding line".
> +#
> +# Disclaimer. The table includes representations of "add" and "and" operations;
> +# corresponding/identical representations of "sub", "inc", "dec" and "or", "xor",
> +# "andnot" operations are omitted.
> +#
> + ------------------------------------------------------------------------------
> + | C macro | Events |
> + ------------------------------------------------------------------------------
> + | Non-RMW ops | |
> + ------------------------------------------------------------------------------
> + | READ_ONCE | R[once] |
> + | atomic_read | |
> + | WRITE_ONCE | W[once] |
> + | atomic_set | |
> + | smp_load_acquire | R[acquire] |
> + | atomic_read_acquire | |
> + | smp_store_release | W[release] |
> + | atomic_set_release | |
> + | smp_store_mb | W[once] ->po F[mb] |
> + | smp_mb | F[mb] |
> + | smp_rmb | F[rmb] |
> + | smp_wmb | F[wmb] |
> + | smp_mb__before_atomic | F[before-atomic] |
> + | smp_mb__after_atomic | F[after-atomic] |
> + | spin_unlock | UL |
> + | spin_is_locked | On success: RL |
> + | | On failure: RU |
> + | smp_mb__after_spinlock | F[after-spinlock] |
> + | smp_mb__after_unlock_lock | F[after-unlock-lock] |
> + | rcu_read_lock | F[rcu-lock] |
> + | rcu_read_unlock | F[rcu-unlock] |
> + | synchronize_rcu | F[sync-rcu] |
> + | rcu_dereference | R[once] |
> + | rcu_assign_pointer | W[release] |
> + | srcu_read_lock | R[srcu-lock] |
> + | srcu_down_read | |
> + | srcu_read_unlock | W[srcu-unlock] |
> + | srcu_up_read | |
> + | synchronize_srcu | SRCU[sync-srcu] |
> + | smp_mb__after_srcu_read_unlock | F[after-srcu-read-unlock] |
> + ------------------------------------------------------------------------------
> + | RMW ops w/o return value | |
> + ------------------------------------------------------------------------------
> + | atomic_add | R*[noreturn] ->rmw W*[once] |
> + | atomic_and | |
> + | spin_lock | LKR ->po LKW |
> + ------------------------------------------------------------------------------
> + | RMW ops w/ return value | |
> + ------------------------------------------------------------------------------
> + | atomic_add_return | F[mb] ->po R*[once] |
> + | | ->rmw W*[once] ->po F[mb] |
> + | atomic_fetch_add | |
> + | atomic_fetch_and | |
> + | atomic_xchg | |
> + | xchg | |
> + | atomic_add_negative | |
> + | atomic_add_return_relaxed | R*[once] ->rmw W*[once] |
> + | atomic_fetch_add_relaxed | |
> + | atomic_fetch_and_relaxed | |
> + | atomic_xchg_relaxed | |
> + | xchg_relaxed | |
> + | atomic_add_negative_relaxed | |
> + | atomic_add_return_acquire | R*[acquire] ->rmw W*[once] |
> + | atomic_fetch_add_acquire | |
> + | atomic_fetch_and_acquire | |
> + | atomic_xchg_acquire | |
> + | xchg_acquire | |
> + | atomic_add_negative_acquire | |
> + | atomic_add_return_release | R*[once] ->rmw W*[release] |
> + | atomic_fetch_add_release | |
> + | atomic_fetch_and_release | |
> + | atomic_xchg_release | |
> + | xchg_release | |
> + | atomic_add_negative_release | |
> + ------------------------------------------------------------------------------
> + | Conditional RMW ops | |
> + ------------------------------------------------------------------------------
> + | atomic_cmpxchg | On success: F[mb] ->po R*[once] |
> + | | ->rmw W*[once] ->po F[mb] |
> + | | On failure: R*[once] |
> + | cmpxchg | |
> + | atomic_add_unless | |
> + | atomic_cmpxchg_relaxed | On success: R*[once] ->rmw W*[once] |
> + | | On failure: R*[once] |
> + | atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[once] |
> + | | On failure: R*[once] |
> + | atomic_cmpxchg_release | On success: R*[once] ->rmw W*[release] |
> + | | On failure: R*[once] |
> + | spin_trylock | On success: LKR ->po LKW |
> + | | On failure: LF |
> + ------------------------------------------------------------------------------
> --
> 2.34.1
>
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