Understanding the -A and the -H flags

Johan Tibell johan.tibell at gmail.com
Tue Feb 28 16:59:52 CET 2012

On Tue, Feb 28, 2012 at 12:57 AM, Simon Marlow <marlowsd at gmail.com> wrote:
> Ah, so I see where your confusion arises - this assumption is not true in
> general.  Just discard the assumption, and I think everything will make more
> sense.
> Picking a size for -A around the L2 cache is often a good idea, but not
> always.  GHC defaults to -A512K, but programs that benefit from much larger
> sizes are quite common.  For more about the tradeoff, see my SO answer here:
> http://stackoverflow.com/questions/3171922/ghcs-rts-options-for-garbage-collection/3172704#3172704

Thanks for the explanation.

One has to be very careful in selecting the size of the allocation
area in benchmarks. If the allocation area is large enough the GC
might not need to run at all for the duration of the benchmark, while
in a real program it would run.

-- Johan

More information about the Glasgow-haskell-users mailing list