Behavior of the -H RTS option, possible doc/impl mismatch

Akio Takano tkn.akio at
Fri Feb 18 09:51:15 CET 2011

Hi Simon,

Thank you for explanation. I think I now understand why -H behaves that way.

2011/2/17 Simon Marlow <marlowsd at>:
> Anyway, with -N2 and above I don't recommend using -H, generally I've found
> it results in lower performance.  -A1m might be good if your CPUs have
> larger L2 caches.  I have some local patches that implement an option like
> -H but which applies to the old generation sizing rather than the nursery,
> which tends to work better with -N2 and above.

An experiment shows my program benefits from larger -H value, at least
with a fixed -A. Also -A256M is much better than -A1M in my case,
perhaps because decreasing the number of minor GCs is very important
to the performance.

-- Takano Akio

> Cheers,
>        Simon

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