Add reference implementation for parallel_phase feature #1570

isaevil · 2024-11-26T16:31:50Z

Description

Add a comprehensive description of proposed changes

Fixes # - issue number(s) if exists

Type of change

Choose one or multiple, leave empty if none of the other choices apply

Add a respective label(s) to PR if you have permissions

bug fix - change that fixes an issue
new feature - change that adds functionality
tests - change in tests
infrastructure - change in infrastructure and CI
documentation - documentation update

Tests

added - required for new features and some bug fixes
not needed

Documentation

updated in # - add PR number
needs to be updated
not needed

Breaks backward compatibility

Yes
No
Unknown

Notify the following users

List users with @ to send notifications

Other information

isaevil · 2024-11-27T09:58:20Z

@akukanov @aleksei-fedotov @vossmjp Could you please take a look at the PR in terms of implementation and ABI.

P.S. Tests are still WIP.

aleksei-fedotov

Not a complete review, just a couple of starters to think about.

src/tbb/waiters.h

src/tbb/arena.h

include/oneapi/tbb/task_arena.h

aleksei-fedotov

A bunch of comments from me. Have not looked at the tests yet. Also, not finished reviewing the PHASE_* switching logic because of found issue.

include/oneapi/tbb/task_arena.h

src/tbb/arena.h

src/tbb/arena.cpp

src/tbb/arena.h

src/tbb/waiters.h

include/oneapi/tbb/task_arena.h

src/tbb/arena.cpp

src/tbb/arena.h

test/tbb/test_task_arena.cpp

aleksei-fedotov · 2024-12-15T23:35:14Z

test/tbb/test_task_arena.cpp

In addition, I think need to cover in tests the following:

The DELAYED_LEAVE is returned back once new task is submitted.

Here I think we can test that the return of a worker after one-time-fast-leave happens generally longer than the following returns made after new task(s) is/are submitted.

Nested parallel phases with combinations of DELAYED and (ONE TIME) FAST leaves.

src/tbb/waiters.h

Signed-off-by: pavelkumbrasev <[email protected]>

Signed-off-by: Isaev, Ilya <[email protected]>

…rallel_block Signed-off-by: Isaev, Ilya <[email protected]>

Signed-off-by: Isaev, Ilya <[email protected]>

Co-authored-by: Aleksei Fedotov <[email protected]>

Signed-off-by: Isaev, Ilya <[email protected]>

src/tbb/arena.cpp

aleksei-fedotov

I think the PR looks good enough as a preview functionality. Consider my other suggestions to ponder on and insignificant remarks. Perhaps, we would be able to "close on" these before fully supporting this feature.

I approve it. Though you might also want implementing Alexey's comment about single fast_leave_policy_flag as well because suggested in-the-patch approach can be implemented in future if we would ever have more than two leave policies.

src/tbb/waiters.h

src/tbb/arena.h

test/tbb/test_task_arena.cpp

src/tbb/waiters.h

src/tbb/arena.h

Signed-off-by: Isaev, Ilya <[email protected]>

test/tbb/test_parallel_phase.cpp

…rena Signed-off-by: Isaev, Ilya <[email protected]>

dnmokhov

LGTM

akukanov

My comments below are not critical; feel free to commit as-is and address later.

include/oneapi/tbb/task_arena.h

akukanov · 2024-12-23T11:53:16Z

include/oneapi/tbb/task_arena.h

+        return fast_policy_set ? leave_policy::fast : leave_policy::automatic;
+    }
+
+    int leave_policy_to_traits(leave_policy lp) const {


Rename to leave_policy_trait?

akukanov · 2024-12-23T11:55:40Z

include/oneapi/tbb/task_arena.h

    task_arena(int max_concurrency_ = automatic, unsigned reserved_for_masters = 1,
-               priority a_priority = priority::normal)
-        : task_arena_base(max_concurrency_, reserved_for_masters, a_priority)
+               priority a_priority = priority::normal
+#if __TBB_PREVIEW_PARALLEL_PHASE
+                    , leave_policy lp = leave_policy::automatic
+#endif


Indentation seems a bit misaligned.

akukanov · 2024-12-23T12:07:03Z

src/tbb/arena.h

+    static const std::uint64_t DELAYED_LEAVE = 1 << 2;
+    static const std::uint64_t PARALLEL_PHASE = 1 << 3;
+
+    std::atomic<std::uint64_t> my_state{0};


Not sure if 64-bit atomic is really needed. Even if it's only 32 bit, 2^29 seems quite enough for the amount of simultaneous parallel phases. The benefit would be better support for 32 bit platforms, but maybe it's negligible.

Changed it to uintptr_t.

akukanov · 2024-12-23T12:13:18Z

src/tbb/arena.h

+
+    std::atomic<std::uint64_t> my_state{0};
+public:
+    void set_initial_state(tbb::task_arena::leave_policy lp) {


Since this is essentially the constructor, please add a comment that this method is required to be called soon after construction, and is not thread-safe. Or maybe consider converting it into a real constructor.

Added a comment.

akukanov · 2024-12-23T12:37:26Z

src/tbb/arena.h

+        }
+    }
+
+    void restore_default_policy_if_needed() {


I would just call it reset (or reset_if_needed) for better encapsulation.

Done. Renamed it to reset_if_needed.

akukanov · 2024-12-23T12:46:07Z

src/tbb/arena.h

+    static const std::uint64_t FAST_LEAVE = 1;
+    static const std::uint64_t ONE_TIME_FAST_LEAVE = 1 << 1;
+    static const std::uint64_t DELAYED_LEAVE = 1 << 2;


In principle, you only need 2 bits, not 3. One bit could be set at construction. indicating "default" fast leave; the other could be set for one-time fast leave. Both bits unset would mean delayed leave. I think that might also simplify the implementation logic.

I didn't find how it would change the implementation logic. But at least we leave one more bit for parallel phase ref counting :)

vossmjp · 2025-01-14T19:23:59Z

include/oneapi/tbb/task_arena.h

@@ -95,6 +95,11 @@ TBB_EXPORT void __TBB_EXPORTED_FUNC isolate_within_arena(d1::delegate_base& d, s
 TBB_EXPORT void __TBB_EXPORTED_FUNC enqueue(d1::task&, d1::task_arena_base*);
 TBB_EXPORT void __TBB_EXPORTED_FUNC enqueue(d1::task&, d1::task_group_context&, d1::task_arena_base*);
 TBB_EXPORT void __TBB_EXPORTED_FUNC submit(d1::task&, d1::task_group_context&, arena*, std::uintptr_t);
+
+#if __TBB_PREVIEW_PARALLEL_PHASE
+TBB_EXPORT void __TBB_EXPORTED_FUNC register_parallel_phase(d1::task_arena_base*, std::uintptr_t);


Is there a reason to use "register" and "unregister" in the names for the entry points? To me "registration" does not imply the start and end of the active time in the region, but might be used to indicate that a region just exists. For example, an athlete might register for a race but that doesn't mean they've started running.

I think the main idea was to use more generic names, which do not depend on feature API. So, if API will change dramatically, entry point names would still make some sense.

vossmjp · 2025-01-14T21:10:51Z

test/tbb/test_parallel_phase.cpp

+    auto median_automatic = utils::median(times_automatic.begin(), times_automatic.end());
+    auto median_fast = utils::median(times_fast.begin(), times_fast.end());
+
+    WARN_MESSAGE(median_automatic < median_fast,


Are all of the tests guaranteed to work (i.e. not have warnings) for hybrid systems where automatic is not delayed leave?

That is a good question. I suppose that only one test case(Parallel Phase retains workers in task_arena) would produce expected results on hybrid systems. Other tests don't make much sense on such configurations, but I think it is fine since these are warnings, not asserts.

Co-authored-by: Alexey Kukanov <[email protected]> Signed-off-by: Isaev, Ilya <[email protected]>

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil · 2025-01-15T17:44:58Z

@aleksei-fedotov @akukanov @vossmjp @pavelkumbrasev @dnmokhov I have updated the RFC document: included some technical details and conditions to leave the experimental stage.

github-actions bot added enhancement tests labels Nov 26, 2024

isaevil changed the title ~~Add reference implementation of parallel_block feature~~ Add reference implementation for parallel_block feature Nov 26, 2024

isaevil requested review from aleksei-fedotov, akukanov and dnmokhov November 27, 2024 09:56

aleksei-fedotov reviewed Nov 28, 2024

View reviewed changes

src/tbb/waiters.h Outdated Show resolved Hide resolved

src/tbb/arena.h Outdated Show resolved Hide resolved

src/tbb/arena.h Outdated Show resolved Hide resolved

include/oneapi/tbb/task_arena.h Outdated Show resolved Hide resolved

akukanov reviewed Dec 2, 2024

View reviewed changes

include/oneapi/tbb/task_arena.h Outdated Show resolved Hide resolved

dnmokhov reviewed Dec 4, 2024

View reviewed changes

include/oneapi/tbb/task_arena.h Outdated Show resolved Hide resolved

isaevil changed the title ~~Add reference implementation for parallel_block feature~~ Add reference implementation for parallel_phase feature Dec 4, 2024

aleksei-fedotov reviewed Dec 6, 2024

View reviewed changes

akukanov reviewed Dec 10, 2024

View reviewed changes

include/oneapi/tbb/task_arena.h Outdated Show resolved Hide resolved

include/oneapi/tbb/task_arena.h Outdated Show resolved Hide resolved

isaevil marked this pull request as ready for review December 13, 2024 15:19

aleksei-fedotov reviewed Dec 15, 2024

View reviewed changes

isaevil requested review from vossmjp, aleksei-fedotov, akukanov, pavelkumbrasev and dnmokhov December 17, 2024 11:21

pavelkumbrasev and others added 10 commits December 17, 2024 12:28

Add initial impl of Parallel Block

5e5778e

Signed-off-by: pavelkumbrasev <[email protected]>

Add test for workers_leave

55fd835

Signed-off-by: pavelkumbrasev <[email protected]>

Fix thread_leave_manager

637a74d

Signed-off-by: pavelkumbrasev <[email protected]>

Add parallel_block API, improve tests

eb172a7

Signed-off-by: Isaev, Ilya <[email protected]>

Improve tests for parallel_block

7f08af0

Signed-off-by: Isaev, Ilya <[email protected]>

Add workers_leave::automatic, let hybric systems take advantage of pa…

f6a139a

…rallel_block Signed-off-by: Isaev, Ilya <[email protected]>

Fix Windows compilation

0a9faed

Signed-off-by: Isaev, Ilya <[email protected]>

Add win32 exports

c1802a1

Signed-off-by: Isaev, Ilya <[email protected]>

Add mac64 symbols

ecd5a9e

Signed-off-by: Isaev, Ilya <[email protected]>

Correct mask, add a clarifying comment to it

0d32f80

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil and others added 6 commits December 17, 2024 12:28

Improve test reporting, move thread demand into internals

7311cec

Signed-off-by: Isaev, Ilya <[email protected]>

Extend testing suite with scoped phases and test with this_task_arena

1f22bc6

Signed-off-by: Isaev, Ilya <[email protected]>

Apply suggestions from code review

fd4a24f

Co-authored-by: Aleksei Fedotov <[email protected]>

Simplify state transition logic

77985c0

Signed-off-by: Isaev, Ilya <[email protected]>

Align leave_policy variables names across code

1a6b73c

Signed-off-by: Isaev, Ilya <[email protected]>

Move parallel phase tests into a separate file

398d16b

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil force-pushed the dev/pavelkumbrasev/parallel_block branch from b93e59e to 398d16b Compare December 17, 2024 15:07

akukanov reviewed Dec 17, 2024

View reviewed changes

src/tbb/arena.cpp Outdated Show resolved Hide resolved

aleksei-fedotov previously approved these changes Dec 17, 2024

View reviewed changes

Address comments

4dfaf5e

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil dismissed aleksei-fedotov’s stale review via 4dfaf5e December 18, 2024 13:52

dnmokhov reviewed Dec 20, 2024

View reviewed changes

test/tbb/test_parallel_phase.cpp Outdated Show resolved Hide resolved

Decrease the size of dummy work, don't execute tests for workerless a…

6a951bd

…rena Signed-off-by: Isaev, Ilya <[email protected]>

dnmokhov previously approved these changes Dec 20, 2024

View reviewed changes

akukanov reviewed Dec 23, 2024

View reviewed changes

isaevil dismissed dnmokhov’s stale review via c05d9a7 January 14, 2025 11:36

vossmjp reviewed Jan 14, 2025

View reviewed changes

isaevil and others added 2 commits January 15, 2025 15:26

Apply suggestions from code review

9d507ca

Co-authored-by: Alexey Kukanov <[email protected]> Signed-off-by: Isaev, Ilya <[email protected]>

Improve test stability

515fd33

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil force-pushed the dev/pavelkumbrasev/parallel_block branch from c05d9a7 to 515fd33 Compare January 15, 2025 14:34

isaevil added 4 commits January 15, 2025 16:07

Use uintptr_t

0f233bb

Signed-off-by: Isaev, Ilya <[email protected]>

Update copyright years

15c3ea5

Signed-off-by: Isaev, Ilya <[email protected]>

Reduce testing time

f041f3a

Signed-off-by: Isaev, Ilya <[email protected]>

Move RFC to the experimental stage

fdae151

Signed-off-by: Isaev, Ilya <[email protected]>

isaevil requested review from akukanov, vossmjp, aleksei-fedotov and dnmokhov January 15, 2025 17:41

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add reference implementation for parallel_phase feature #1570

Add reference implementation for parallel_phase feature #1570

isaevil commented Nov 26, 2024

isaevil commented Nov 27, 2024 •

edited

Loading

aleksei-fedotov left a comment

aleksei-fedotov left a comment

aleksei-fedotov Dec 15, 2024

aleksei-fedotov left a comment

dnmokhov left a comment

akukanov left a comment

akukanov Dec 23, 2024

isaevil Jan 15, 2025

akukanov Dec 23, 2024

isaevil Jan 15, 2025

akukanov Dec 23, 2024

isaevil Jan 15, 2025

akukanov Dec 23, 2024

isaevil Jan 17, 2025

akukanov Dec 23, 2024

isaevil Jan 15, 2025 •

edited

Loading

akukanov Dec 23, 2024

isaevil Jan 15, 2025 •

edited

Loading

vossmjp Jan 14, 2025

isaevil Jan 15, 2025

vossmjp Jan 14, 2025

isaevil Jan 15, 2025 •

edited

Loading

isaevil commented Jan 15, 2025

Add reference implementation for parallel_phase feature #1570

Are you sure you want to change the base?

Add reference implementation for parallel_phase feature #1570

Conversation

isaevil commented Nov 26, 2024

Description

Type of change

Tests

Documentation

Breaks backward compatibility

Notify the following users

Other information

isaevil commented Nov 27, 2024 • edited Loading

aleksei-fedotov left a comment

Choose a reason for hiding this comment

aleksei-fedotov left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

aleksei-fedotov left a comment

Choose a reason for hiding this comment

dnmokhov left a comment

Choose a reason for hiding this comment

akukanov left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

isaevil Jan 15, 2025 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

isaevil Jan 15, 2025 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

isaevil Jan 15, 2025 • edited Loading

Choose a reason for hiding this comment

isaevil commented Jan 15, 2025

isaevil commented Nov 27, 2024 •

edited

Loading

isaevil Jan 15, 2025 •

edited

Loading

isaevil Jan 15, 2025 •

edited

Loading

isaevil Jan 15, 2025 •

edited

Loading