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SubjectRe: [PATCH] lib: Make _find_next_bit helper function inline
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Hi Cassidy,


On Wed, Jul 29, 2015 at 11:40 PM, Cassidy Burden <cburden@codeaurora.org> wrote:
> I changed the test module to now set the entire array to all 0/1s and
> only flip a few bits. There appears to be a performance benefit, but
> it's only 2-3% better (if that). If the main benefit of the original
> patch was to save space then inlining definitely doesn't seem worth the
> small gains in real use cases.
>
> find_next_zero_bit (us)
> old new inline
> 14440 17080 17086
> 4779 5181 5069
> 10844 12720 12746
> 9642 11312 11253
> 3858 3818 3668
> 10540 12349 12307
> 12470 14716 14697
> 5403 6002 5942
> 2282 1820 1418
> 13632 16056 15998
> 11048 13019 13030
> 6025 6790 6706
> 13255 15586 15605
> 3038 2744 2539
> 10353 12219 12239
> 10498 12251 12322
> 14767 17452 17454
> 12785 15048 15052
> 1655 1034 691
> 9924 11611 11558
>
> find_next_bit (us)
> old new inline
> 8535 9936 9667
> 14666 17372 16880
> 2315 1799 1355
> 6578 9092 8806
> 6548 7558 7274
> 9448 11213 10821
> 3467 3497 3449
> 2719 3079 2911
> 6115 7989 7796
> 13582 16113 15643
> 4643 4946 4766
> 3406 3728 3536
> 7118 9045 8805
> 3174 3011 2701
> 13300 16780 16252
> 14285 16848 16330
> 11583 13669 13207
> 13063 15455 14989
> 12661 14955 14500
> 12068 14166 13790
>
> On 7/29/2015 6:30 AM, Alexey Klimov wrote:
>>
>> I will re-check on another machine. It's really interesting if
>> __always_inline makes things better for aarch64 and worse for x86_64. It
>> will be nice if someone will check it on x86_64 too.
>
>
> Very odd, this may be related to the other compiler optimizations Yuri
> mentioned?

It's better to ask Yury, i hope he can answer some day.

Do you need to re-check this (with more iterations or on another machine(s))?

--
Best regards, Klimov Alexey


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