#3553: parallel gc suffers badly if one thread is descheduled
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Reporter: simonmar | Owner: igloo
Type: merge | Status: new
Priority: normal | Milestone: 6.12.2
Component: Runtime System | Version: 6.10.4
Keywords: | Difficulty: Unknown
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by wuzzeb):
I would be careful about adding sched_yield. Ingo Molnar, the developer
who wrote and maintains the linux scheduler, says he has never seen a
valid use of sched_yield. See
http://kerneltrap.org/Linux/Using_sched_yield_Improperly for the
discussion. At least with the CFS scheduler in linux, using sched_yield
might not always do what you expect.
Also, from your blog post at least, it seems like futexes are perfect for
what you need. In the uncontended case, they are completely in userspace.
They can be acquired on one thread and released on another thread. Any
reasons why futexes don't work?
http://people.redhat.com/drepper/futex.pdf
http://en.wikipedia.org/wiki/Futex
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3553#comment:3>
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