Re: [PATCHv8 02/34] lib/vdso: make do_hres and do_coarse as __always_inline

[Vincenzo Frascino]

On 1/10/20 12:02 PM, Thomas Gleixner wrote:
> Vincenzo Frascino <vincenzo.frascino@xxxxxxx> writes:
>> On 1/10/20 11:42 AM, Thomas Gleixner wrote:
>>>>> +Â Â /*ÂgotoÂallowsÂtoÂavoidÂextraÂinliningÂofÂdo_hres.Â*/
>>>>> +Â Â gotoÂout_hres;
>>>>
>>>> What is the performance impact of "goto out_hres"?
>>>
>>> On x86 it's invisible at least in my limited testing.
>>
>> On arm64 as well based on mine as well. Shall we keep the code more readable
>> here (without goto)?
> 
> The delta patch below makes it readable again and also avoids the double
> inlining. Quick testing shows no difference.
>

I tested it on arm64 and it does not show any difference as well.
I vote for it :)

> Thanks,
> 
>         tglx
> 
> 8<---------------
> --- a/lib/vdso/gettimeofday.c
> +++ b/lib/vdso/gettimeofday.c
> @@ -98,17 +98,15 @@ static __maybe_unused int
>  	msk = 1U << clock;
>  	if (likely(msk & VDSO_HRES)) {
>  		vd = &vd[CS_HRES_COARSE];
> -out_hres:
> -		return do_hres(vd, clock, ts);
>  	} else if (msk & VDSO_COARSE) {
>  		do_coarse(&vd[CS_HRES_COARSE], clock, ts);
>  		return 0;
>  	} else if (msk & VDSO_RAW) {
>  		vd = &vd[CS_RAW];
> -		/* This goto avoids extra inlining of do_hres. */
> -		goto out_hres;
> +	} else {
> +		return -1;
>  	}
> -	return -1;
> +	return do_hres(vd, clock, ts);
>  }
>  
>  static __maybe_unused int
> 

-- 
Regards,
Vincenzo