Re: [PATCH/RFC/PR28071]: New scheduler dependencies lists.

[Maxim Kuvyrkov <mkuvyrkov at ispras dot ru>]

Jan Hubicka wrote:
> Hi,
> the memory tester jammed for last week, but looking at the results
> on the PR28071 -O3 compilation at:
> http://www.suse.de/~gcctest/memory/graphs/index.html
> it looks like that while this patch sucesfully addressed the compilation
> time issues, the overall memory consumption increased noticeably (100MB,
> or 20%)

Hi,

I tested my patch on PR28071 testcase on x86_64 and got the following 
numbers:

Revisions of interest: r121493 (the one before my patch), r121494 (the 
one after my patch).

configure: --enable-languages=c --enable-checking=release 
--enable-gather-detailed-mem-stats --disable-bootstrap

maxmem.sh:
r121493: 701M
r121494: 440M

-fmem-report 'Total Allocated':
r121493: 565973016
r121494: 337328408

-fmem-report 'Total Overhead':
r121493: 91480975
r121494: 34319823

> I think it might be caused just by suboptimal allocation (as the lists
> with extra pointer should not consume more memory just because RTL
> containers did needed extra 64bits too).
>
> Looking at the code:
> > +/* Allocate deps_list.
> > +
> > +   If ON_OBSTACK_P is true, allocate the list on the obstack.  This is done for
> > +   INSN_FORW_DEPS lists because they should live till the end of scheduling.
> > +
> > +   INSN_BACK_DEPS and INSN_RESOLVED_BACK_DEPS lists are allocated on the free
> > +   store and are being freed in haifa-sched.c: schedule_insn ().  */
> > +static deps_list_t
> > +alloc_deps_list (bool on_obstack_p)
> > +{
> > +  if (on_obstack_p)
> > +    return obstack_alloc (dl_obstack, sizeof (struct _deps_list));
> > +  else
> > +    return xmalloc (sizeof (struct _deps_list));
> > +}
>
> This seems to be obvious candidate for allocpools instead of
> this obstack/xmalloc hybrid scheme. ...

I'm now testing the patch that among other things changes obstacks into 
alloc_pools, but on this testcase it gives exactly the same results as 
current obstack implementation.  So that is not the problem.


Thanks,

Maxim