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| author | Simon Marlow <marlowsd@gmail.com> | 2014-11-21 17:05:58 +0000 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2014-11-25 14:37:26 +0000 |
| commit | 452eb80f15fce8665df52bc9facebfafb5b6267b (patch) | |
| tree | a34e76ab765b6d1db49b1c05372f8924e52cacf9 /docs | |
| parent | e22bc0dedb9e9da0176ad7ce4a74acbefedc7207 (diff) | |
| download | haskell-452eb80f15fce8665df52bc9facebfafb5b6267b.tar.gz | |
Add +RTS -n<size>: divide the nursery into chunks
See the documentation for details.
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/runtime_control.xml | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/docs/users_guide/runtime_control.xml b/docs/users_guide/runtime_control.xml index cdd9fd4997..612a44122a 100644 --- a/docs/users_guide/runtime_control.xml +++ b/docs/users_guide/runtime_control.xml @@ -365,6 +365,42 @@ $ ./prog -f +RTS -H32m -S -RTS -h foo bar </varlistentry> <varlistentry> + <term> + <option>-n</option><replaceable>size</replaceable> + <indexterm><primary><option>-n</option></primary><secondary>RTS option</secondary></indexterm> + <indexterm><primary>allocation area, chunk size</primary></indexterm> + </term> + <listitem> + <para>[Default: 0, Example: + <literal>-n4m</literal>] When set to a non-zero value, + this option divides the allocation area (<option>-A</option> + value) into chunks of the specified size. During execution, + when a processor exhausts its current chunk, it is given + another chunk from the pool until the pool is exhausted, at + which point a collection is triggered.</para> + + <para>This option is only useful when running in parallel + (<option>-N2</option> or greater). It allows the processor + cores to make better use of the available allocation area, + even when cores are allocating at different rates. Without + <option>-n</option>, each core gets a fixed-size allocation + area specified by the <option>-A</option>, and the first + core to exhaust its allocation area triggers a GC across all + the cores. This can result in a collection happening when + the allocation areas of some cores are only partially full, + so the purpose of the <option>-n</option> is to allow cores + that are allocating faster to get more of the allocation + area. This means less frequent GC, leading a lower GC + overhead for the same heap size.</para> + + <para>This is particularly useful in conjunction with larger + <option>-A</option> values, for example <option>-A64m + -n4m</option> is a useful combination on larger core counts + (8+).</para> + </listitem> + </varlistentry> + + <varlistentry> <term> <option>-c</option> <indexterm><primary><option>-c</option></primary><secondary>RTS option</secondary></indexterm> |