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Re: [RFA] update ggc_min_heapsize_heuristic()
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Markus Trippelsdorf <markus at trippelsdorf dot de>
- Cc: "Richard Earnshaw (lists)" <Richard dot Earnshaw at arm dot com>, Alexander Monakov <amonakov at ispras dot ru>, gcc at gcc dot gnu dot org
- Date: Mon, 10 Apr 2017 06:06:55 -0500
- Subject: Re: [RFA] update ggc_min_heapsize_heuristic()
- Authentication-results: sourceware.org; auth=none
- References: <20170409144125.GA10606@x4> <alpine.LNX.2.20.13.1704092108210.4498@monopod.intra.ispras.ru> <20170409191019.GA294@x4> <20170409200621.GC294@x4> <9f82f10b-f72c-08a9-9bca-fd11e9a259fc@arm.com> <20170410101537.GA11802@x4> <20170410105215.GB11802@x4>
On Mon, Apr 10, 2017 at 12:52:15PM +0200, Markus Trippelsdorf wrote:
> > --param ggc-min-heapsize=131072
> > 11264.89user 311.88system 24:18.69elapsed 793%CPU (0avgtext+0avgdata 1265352maxresident)k
>
> --param ggc-min-heapsize=262144
> 10778.52user 336.34system 23:15.71elapsed 796%CPU (0avgtext+0avgdata 1277468maxresident)k
>
> > --param ggc-min-heapsize=393216
> > 10655.42user 347.92system 23:01.17elapsed 796%CPU (0avgtext+0avgdata 1280476maxresident)k
> >
> > --param ggc-min-heapsize=524288
> > 10565.33user 352.90system 22:51.33elapsed 796%CPU (0avgtext+0avgdata 1506348maxresident)k
So 256MB gets 70% of the speed gain of 512MB, but for only 5% of the cost
in RSS. 384MB is an even better tradeoff for this testcase (but smaller
is safer).
Can the GC not tune itself better? Or, not cost so much in the first
place ;-)
Segher