> On Aug 1, 2015, at 21:32, Neil Horman <nhor...@redhat.com> wrote:
>
> On Sat, Aug 01, 2015 at 03:12:42PM +0800, yalin wang wrote:
>>
>>> 在 2015年7月31日，22:14，Thomas Gleixner <t...@linutronix.de> 写道：
>>>
>>>
>>> On Fri, 31 Jul 2015, Thomas Gleixner wrote:
>>>
>>>> On Fri, 31 Jul 2015, yalin wang wrote:
>>>>> it is optimised to 2 instructions ,
>>>>>
>>>>> this is my patch, hope can be merged :
>>>>
>>>> We are not exposing the internals of kthread management. Period.
>>>
>>> And your 'optimization' is completely bogus:
>>>
>>> Before your modification:
>>>
>>> size kernel/built-in.o
>>>
>>> text data bss dec hex filename
>>> 1091514 141498 341928 1574940 18081c ../build/kernel/built-in.o
>>>
>>> After:
>>>
>>> text data bss dec hex filename
>>> 1091664 141498 341928 1575090 1808b2 ../build/kernel/built-in.o
>>>
>>> That's an increase of text size by 150 byte. Interesting optimization.
>>>
>>> Thanks,
>>>
>>> tglx
>>>
>>>
>> strange, this is my test result:
>>
>> size built-in.o*
>> text data bss dec hex filename
>> 743937 50786 56008 850731 cfb2b built-in.o // with the
>> patch
>> 744069 50786 56008 850863 cfbaf built-in.o_old // with out the
>> patch
>>
> So you're willing to expose the internals of kthread_park in exchange for the
> hope of saving 132 bytes of text.
>
> Thats just dumb. I agree with tglx, this shouldn't change.
>
> Neil
not just size, mainly for performance,
without inline:
ffffffc0000d26b0: 97fff4aa bl ffffffc0000cf958
<kthread_should_park>
ffffffc0000d26b4: 53001c00 uxtb w0, w0
if kthread_should_park() inline:
ffffffc0000d1a44: f85c8020 ldr x0, [x1,#-56]
// kthread_should_park
line
ffffffc0000d1a48: 36100300 tbz w0, #2, ffffffc0000d1aa8
<smpboot_thread_fn+0xbc> // kthread_should_park line
still use 2 instructions, but don’t need a function call,
maybe can do more optimisation by gcc sometimes .
Anyway, this is just a suggest,
it is up to you apply it or not. :)
Thanks
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