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| author | Simon Marlow <marlowsd@gmail.com> | 2010-03-29 14:44:56 +0000 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2010-03-29 14:44:56 +0000 |
| commit | 5d52d9b64c21dcf77849866584744722f8121389 (patch) | |
| tree | 25aeafc9b761e73714c24ae414c0b1c41765c99f /rts/Schedule.h | |
| parent | 79957d77c1bff767f1041d3fabdeb94d92a52878 (diff) | |
| download | haskell-5d52d9b64c21dcf77849866584744722f8121389.tar.gz | |
New implementation of BLACKHOLEs
This replaces the global blackhole_queue with a clever scheme that
enables us to queue up blocked threads on the closure that they are
blocked on, while still avoiding atomic instructions in the common
case.
Advantages:
- gets rid of a locked global data structure and some tricky GC code
(replacing it with some per-thread data structures and different
tricky GC code :)
- wakeups are more prompt: parallel/concurrent performance should
benefit. I haven't seen anything dramatic in the parallel
benchmarks so far, but a couple of threading benchmarks do improve
a bit.
- waking up a thread blocked on a blackhole is now O(1) (e.g. if
it is the target of throwTo).
- less sharing and better separation of Capabilities: communication
is done with messages, the data structures are strictly owned by a
Capability and cannot be modified except by sending messages.
- this change will utlimately enable us to do more intelligent
scheduling when threads block on each other. This is what started
off the whole thing, but it isn't done yet (#3838).
I'll be documenting all this on the wiki in due course.
Diffstat (limited to 'rts/Schedule.h')
| -rw-r--r-- | rts/Schedule.h | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/rts/Schedule.h b/rts/Schedule.h index 2412285d29..0db2b1ed84 100644 --- a/rts/Schedule.h +++ b/rts/Schedule.h @@ -86,15 +86,6 @@ extern StgTSO *blocked_queue_hd, *blocked_queue_tl; extern StgTSO *sleeping_queue; #endif -/* Set to rtsTrue if there are threads on the blackhole_queue, and - * it is possible that one or more of them may be available to run. - * This flag is set to rtsFalse after we've checked the queue, and - * set to rtsTrue just before we run some Haskell code. It is used - * to decide whether we should yield the Capability or not. - * Locks required : none (see scheduleCheckBlackHoles()). - */ -extern rtsBool blackholes_need_checking; - extern rtsBool heap_overflow; #if defined(THREADED_RTS) |