Jan Hubicka - Re: [PATCH/RFC/PR28071]: New scheduler dependencies lists. (original) (raw)

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• From: Jan Hubicka
• To: Maxim Kuvyrkov
• Cc: Vladimir Makarov , James E Wilson , Ayal Zaks , Andrey Belevantsev , Revital1 Eres , gcc-patches at gcc dot gnu dot org
• Date: Sun, 4 Feb 2007 22:49:57 +0100
• Subject: Re: [PATCH/RFC/PR28071]: New scheduler dependencies lists.
• References: 45B5BC60.8000809@ispras.ru

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%)

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. Also I am just curious, what is the advantage of using the pointers back to the next field instead of usual doubly linked list? Thanks for all the hard work!

Honza

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    * From: Ayal Zaks
  • Re: [PATCH/RFC/PR28071]: New scheduler dependencies lists.
    * From: Maxim Kuvyrkov