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Threading Building Blocks Early March 2008 Development Releases
By Kevin Farnham (108 posts) on March 14, 2008 at 7:32 pm
The Threading Building Blocks development team has moved to a weekly development release schedule recently: there have already been two early March releases following the February 26 release that I blogged about in my last post. In this post, I aim to catch up with the development team!
2008 March 4 TBB Development release
The CHANGES file for the tbb20_20080304oss development release highlights these changes:
- Task-to-thread affinity support, previously kept under a macro, now fully legalized.
- Work-in-progress on cache_aligned_allocator improvements.
- Pipeline really supports parallel input stage; it's no more serialized.
- Various improvements to code, tests, examples and Makefiles.
and these bug fixes:
- 119 - fix for scalable_malloc sometimes failing to return a big block.
- TR575 - fixed a deadlock occurring on Windows in startup/shutdown under some conditions.
An important thing to note here is the Bug 119 fix. This is a bug that was entered by "uj" into the public TBB bug database. I've been telling people for a while that, while the online TBB bug database doesn't contain every bug (the internal bug list hasn't yet been merged into the public bug database), it's still very worthwhile for TBB users to post bugs into the public database, because the TBB development team pays attention to everything that's posted there. If you find what you believe may be a bug, please do take the time to post the bug, and help improve TBB!
A quick look at a diff of the 20080226 and 20080304 releases shows significant changes (mostly additions) to the cache_aligned_allocator.cpp and pipeline.cpp files in src/tbb, and many changes in src/tbb/task.cpp related to affinity. A lot of other files have a few altered lines, many of which are again related to the affinity changes mentioned in the CHANGES file.
The test_pipeline.cpp and test_task.cpp files in the src/test directory were significantly modified to better test the new pipeline and task changes.
2008 March 11 TBB Development release
The tbb20_20080311oss development release CHANGES files lists the following changes:
- An enumerator added for pipeline filter types (serial vs. parallel).
- New task_scheduler_observer class introduced, to observe when threads start and finish interacting with the TBB task scheduler.
- task_scheduler_init reverted to not use internal versioned class; binary compatibility guaranteed with stable releases only.
- Various improvements to code, tests, examples and Makefiles.
To me, the new task_scheduler_observor class is quite interesting. It would seem that this class will empower developers with capability to tune their applications for greater efficiency and performance. I'd like to investigate this new class more thoroughly in a future post.
Looking at a diff between the 20080304 and 20080311 development releases, changes in src/tbb/task.cpp stand out in terms of number of changed lines (most of them additions). This backs up my expressed interest in the new task_scheduler_observor class, since much of the code for the observor is in the task.cpp file. Further investigation of this is promised!
Conclusion
It's clear that the TBB development team is hard at work. The team is working toward an upcoming significant release--maybe not a 3.0, but a 2.1 anyway. I encourage those who are experimenting with TBB to download and work with the later development releases. There's a lot there that is not available in the latest stable or commercial-aligned releases. And, from what I'm told, much of what's in these recent development releases--all the new features and improvements to the base code, the tests, the examples--is likely to solidify into a highly-stable commercial-aligned release sometime in the next few months. I heartily encourage TBB experimenters to work with the latest TBB development releases.
Kevin Farnham, O'Reilly Media TBB Open Source Community, Freenode IRC #tbb, TBB Mailing Lists
Categories: Multicore, Open Source, Threading Building Blocks
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