simplify algorithms of synchronization objects #268
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
ABTI_waitlist is a helper to suspend and resume multiple threads, which is useful to implement synchronization objects. The next commit will change the implementation of existing synchronization objects.
This patch uses ABTI_waitlist for synchronization objects including ABT_barrier, ABT_cond, ABT_eventual, and ABT_future. This can reduce the common code that manages a queue of waiting threads.
The mutex logic that uses ABTI_thread_htable is broken and hard to fix. This patch removes this implementation. Note that this algorithm is disabled by default (which can be turned on by passing --disable-simple-mutex).
The current busy-yield-based implementation can easily make pools full of waiting threads, which is inefficient. ABTI_waitlist-based implementation can avoid such a case. Note that by default ABT_mutex will use busy-yield-based implementation in order not to change the default performance of ABT_mutex. For example, the original implementation performs better if there is no contention. ABTI_waitlist-based implementation can be enabled by passing --disable-simple-mutex at configuration time.
|
test:argobots/all |
4 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Problem
The implementations of synchronization objects are overlapped but differently written in each file. Specifically, the core algorithm of synchronization objects is managing a queue of waiting threads, but
ABT_cond,ABT_barrier,ABT_future, andABT_eventualuse similar but different code.ABT_mutexuses an incorrect queue implementation (see #14, #41, and #102).Solution
To avoid code duplication, this PR implements
ABTI_waitlist.ABT_mutexwill use this when--disable-simple-mutexis passed; by default the existing yield-based implementation is used. BetterABT_muteximplementation is our future work.Expected impact
This change significantly affects the performance of
ABT_mutexwith--disable-simple-mutex. The new implementation is correct but slower in some cases. This PR should not affect the performance of the other synchronization objects (includingABT_mutexwithout--disable-simple-mutex) much -- this PR should make them faster.