On Thu, Sep 26, 2013 at 3:27 PM, Jan Hubicka wrote:
>> Hi,
>>
>> Current default probably for builtin_expect is 0.9996.
>> This makes the freq of unlikely bb very low (4), which
>> suppresses the inlining of any calls within those bb.
>>
>> We used FDO data to measure the branch probably for
>> th
it might worth extend __builtin_expect to take more parameters:
1) argument to specify actual probability: __builtin_expect (x, 10, 0.6)
2) a more general way of doing this is to allow specifying multiple
values, and the probability is determined by # of occurances:
__builtin_expect (x, 10, 10, 20)
This patch improves linux kernel performance with a large workload, so
it is good to first submit this to trunk and backport it.
thanks,
David
On Thu, Sep 26, 2013 at 3:27 PM, Jan Hubicka wrote:
>> Hi,
>>
>> Current default probably for builtin_expect is 0.9996.
>> This makes the freq of unlike
> Hi,
>
> Current default probably for builtin_expect is 0.9996.
> This makes the freq of unlikely bb very low (4), which
> suppresses the inlining of any calls within those bb.
>
> We used FDO data to measure the branch probably for
> the branch annotated with builtin_expert.
>
