PR 54075 Restore 4.6 growth factor

[François Dumont]

Patch applied. I usually CC to gcc-patches when I signal that it has 
been applied. Should I send it all my patch proposals ?

François

On 07/28/2012 11:18 PM, Jonathan Wakely wrote:
> Please remember to CC gcc-patches too.
>
> On 28 July 2012 21:49, François Dumont wrote:
>> Hi
>>
>>      Here is the patch to restore the 4.6 growth factor of 2. I prefer to
>> validate the restored behavior by adding a performance test. Without the
>> patch the result was:
>>
>> unordered_set.cc             unordered_set 10000000 insertions  403r  329u
>> 73s 402825280mem    0pf
>>
>> after the patch:
>>
>> unordered_set.cc             unordered_set 10000000 insertions  112r   86u
>> 25s 402825104mem    0pf
>>
>> It validates the 3x times performance hint.
>>
>> Tested under Linux x86_64.
>>
>> 2012-07-28  François Dumont  <fdumont@gcc.gnu.org>
>>
>>      PR libstdc++/54075
>>      * include/bits/hashtable_policy.h
>>      (_Prime_rehash_policy::_M_next_bkt): Add a growth factor set to 2
>>      to boost growth in the number of buckets.
>>      * testsuite/performance/23_containers/insert/unordered_set.cc: New.
>>
>> Even if it is not a Standard conformity issue I think we can apply it to the
>> 4.7 branch too.
> Yes, it's a performance regression, so this is OK for trunk and 4.7, thanks.

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