Add reference implementation for parallel_phase feature #1570

isaevil · 2024-11-26T16:31:50Z

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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]>

Co-authored-by: Aleksei Fedotov <[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.

akukanov · 2024-12-23T11:51:01Z

include/oneapi/tbb/task_arena.h

+        bool fast_policy_set = (my_version_and_traits & fast_leave_policy_flag) == fast_leave_policy_flag;
+        return fast_policy_set ? leave_policy::fast : leave_policy::automatic;


Suggested change

bool fast_policy_set = (my_version_and_traits & fast_leave_policy_flag) == fast_leave_policy_flag;

return fast_policy_set ? leave_policy::fast : leave_policy::automatic;

return (my_version_and_traits & fast_leave_policy_flag) ? leave_policy::fast : leave_policy::automatic;

It's really the same but shorter :)

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.

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.

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.

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.

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

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akukanov reviewed Dec 2, 2024

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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

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akukanov reviewed Dec 10, 2024

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

aleksei-fedotov reviewed Dec 15, 2024

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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 14 commits December 17, 2024 12:28

Apply suggested typo fix

f61fc1d

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

Rename block to phase

17f1dac

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

Align with RFC, utilize my_version_and_traits, improve readability

aa7cc2a

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

Fix non-preview compilation

104606c

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

Change scoped_parallel_phase default parameter, fix entry points for Win

597136f

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

Apply suggestions from code review

1bc6e3a

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

Apply comments, change tests

73742f3

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

Correct mac64 exports

ba5b922

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

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

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

aleksei-fedotov previously approved these changes Dec 17, 2024

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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

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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 approved these changes Dec 20, 2024

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akukanov reviewed Dec 23, 2024

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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 •

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		bool fast_policy_set = (my_version_and_traits & fast_leave_policy_flag) == fast_leave_policy_flag;
		return fast_policy_set ? leave_policy::fast : leave_policy::automatic;

	bool fast_policy_set = (my_version_and_traits & fast_leave_policy_flag) == fast_leave_policy_flag;
	return fast_policy_set ? leave_policy::fast : leave_policy::automatic;
	return (my_version_and_traits & fast_leave_policy_flag) ? leave_policy::fast : leave_policy::automatic;

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isaevil commented Nov 26, 2024

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Breaks backward compatibility

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isaevil commented Nov 27, 2024 • edited Loading

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isaevil commented Nov 27, 2024 •

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