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[Bug libstdc++/54075] [4.7.1] unordered_map insert 3x slower than 4.6.2
- From: "fdumont at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 24 Oct 2012 19:27:58 +0000
- Subject: [Bug libstdc++/54075] [4.7.1] unordered_map insert 3x slower than 4.6.2
- Auto-submitted: auto-generated
- References: <bug-54075-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54075
--- Comment #30 from FranÃois Dumont <fdumont at gcc dot gnu.org> 2012-10-24 19:27:58 UTC ---
I am going to take a look to 4.4 implementation to see if I can explain the
difference. But waiting for that can you confirm that without the reserve the
number of rehash is similar to what you had with version 4.4.
Regarding the resident memory, I can't remember any overhead with the new
implementation but once again checking 4.4 implementation will point me to it.
Do you have it with the code originally posted, that is to say an
unordered_map<int, int> ?
For information the major reason to review the implementation was for Standard
conformity. The erase method had to return the iterator following the erased
one.