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diff --git a/docs/users_guide/runtime_control.xml b/docs/users_guide/runtime_control.xml
index 62a01ac..725ee88 100644
--- a/docs/users_guide/runtime_control.xml
+++ b/docs/users_guide/runtime_control.xml
@@ -268,6 +268,43 @@
+
+ threads
+ RTS option
+
+
+ [Default: 1] [new in GHC 6.10] Set the number
+ of threads to use for garbage collection. This option is
+ only accepted when the program was linked with the
+ option; see .
+
+ The garbage collector is able to work in parallel when
+ given more than one OS thread. Experiments have shown
+ that this usually results in a performance improvement
+ given 3 cores or more; with 2 cores it may or may not be
+ beneficial, depending on the workload. Bigger heaps work
+ better with parallel GC, so set your
+ value high (3 or more times the maximum residency). Look
+ at the timing stats with to
+ see whether you're getting any benefit from parallel GC or
+ not. If you find parallel GC is
+ significantly slower (in elapsed
+ time) than sequential GC, please report it as a
+ bug.
+
+ This value is set automatically when the
+ option is used, so the only reason to
+ use would be if you wanted to use a
+ different number of threads for GC than for execution.
+ For example, if your program is strictly single-threaded
+ but you still want to benefit from parallel GC, then it
+ might make sense to use rather than
+ .
+
+
+
+ sizeRTS option
@@ -399,46 +436,35 @@
+
+ file
+ RTS option
+
- file
+ fileRTS option
- file
+ fileRTS option
- Write modest () or verbose
- () garbage-collector statistics into file
- file. The default
- file is
- program.stat. The
- filestderr
- is treated specially, with the output really being sent to
- stderr.
-
- This option is useful for watching how the storage
- manager adjusts the heap size based on the current amount of
- live data.
-
-
+ These options produce runtime-system statistics, such
+ as the amount of time spent executing the program and in the
+ garbage collector, the amount of memory allocated, the
+ maximum size of the heap, and so on. The three
+ variants give different levels of detail:
+ produces a single line of output in the
+ same format as GHC's option,
+ produces a more detailed summary at the
+ end of the program, and additionally
+ produces information about each and every garbage
+ collection.
-
-
-
- RTS option
-
-
- Write a one-line GC stats summary after running the
- program. This output is in the same format as that produced
- by the option.
-
- As with , the default
- file is
- program.stat. The
- filestderr
- is treated specially, with the output really being sent to
- stderr.
+ The output is placed in
+ file. If
+ file is omitted, then the output
+ is sent to stderr.