Re: [PATCH 1/4] Add gcc-auto-profile script

[Andi Kleen <ak at linux dot intel dot com>]

On Wed, Apr 27, 2016 at 05:42:48PM +0200, Bernd Schmidt wrote:
> On 03/28/2016 06:44 AM, Andi Kleen wrote:
> >This patch adds a new gcc-auto-profile script that figures out the
> >correct event and runs perf. The script is installed with on Linux systems.
> 
> That sounds useful, and I think we'll want to accept this.
> 
> >So Linux just hardcodes installing the script, but it may fail at runtime.
> 
> For this reason it would probably be best to retain the documentation for
> the old method alongside the new one.

The old method actually doesn't work, unless you apply a very obscure
patch to your perf. I don't think it is very useful for users.

> 
> >+
> >+baseurl = "https://download.01.org/perfmon";
> 
> Slightly scary to see a random unknown download URL. Apparently it's an
> Intel thing? Is this referenced somewhere on an intel.com web page?

http://www.intel.com/content/www/us/en/search.html?toplevelcategory=none&keyword=01.org


> 
> >  E.g.
> >  @smallexample
> >  create_gcov --binary=your_program.unstripped --profile=perf.data \
> >-    --gcov=profile.afdo
> >+    --gcov=profile.afdo -gcov_version 1
> >  @end smallexample
> >  @end table
> 
> Why this change? What does it do?

It actually makes it work. The google autofdo distribution defaults
to some google internal magic gcov version number that doesn't work
with standard gcc.

I can split it out.

> 
> Why isn't the new script in contrib? Does it have to be in gcc to be
> installed?

Because autoprofiledfeedback needs it.

Also the idea was to eventually install it by default (although the patch
doesn't do that yet)

-Andi


-- 
ak@linux.intel.com -- Speaking for myself only