[PATCH] powerpc/configs: Enable function trace by default

[Christophe LEROY]

Le 13/04/2017 à 10:19, Balbir Singh a écrit :
> On Thu, 2017-04-13 at 09:24 +0200, Christophe LEROY wrote:
>> Hi Baldir
>
> Hi Christophe, It's Balbir

Sorry

>
>>
>> Le 13/04/2017 à 09:03, Balbir Singh a écrit :
>>> We expect to have these configs on by default, most
>>> distros turn them off, its always good to have them on
>>> so that we can use them and hopefully not break them
>>
>> Isn't it the purpose of the target allyesconfig to allow such tests ?
>>
>
> As a developer I don't use allyesconfig for submitting patches or testing
> the kernel.

I do it most of the time to check compilation doesn't fail.

>
>> FTRACE is quite CPU consumming, shouldn't it really be on by default ?
>
> It does some work at boot to NOP out function entry points at _mcount
> locations. Is that what you are referring to? Or the overhead of the
> code in terms of size? Most distro kernels have tracing on by default.

You said in you patch text: "most distros turn them off".

If most distros turn it ON (and not OFF as you said), then I can 
understand we have it ON as well in defconfigs.

Christophe

>
> The rest of the overhead is enablement based.
>
> Thanks for the review!
> Balbir Singh
>