X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=docs%2Fusers_guide%2Fruntime_control.xml;h=725ee887dd622c684cdd915cefd002567a8a5a25;hb=9b2cd28e7be049d7abaff2cb9c0cda8eb67932f4;hp=62a01acdda4b35b98dbe307c4a24c7fd48ff538d;hpb=5263c9ab4408e3b62dbf7505ab40a81946d4e49b;p=ghc-hetmet.git 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 + . + + + + size RTS option @@ -399,46 +436,35 @@ + + file + RTS option + - file + file RTS option - file + file RTS option - Write modest () or verbose - () garbage-collector statistics into file - file. The default - file is - program.stat. The - file stderr - 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 - file stderr - 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.