Re: Compile performance of Linux kernels in mainline gcc

[Zack Weinberg <zack at codesourcery dot com>]

Andi Kleen <ak@suse.de> writes:

> Hallo,
>
> Did some comparisons of the compile speed of current mainline compared to the
> 3.3-hammer compiler from suse 9.1. Test environment is a fast dual EM64T 
> box with HyperThreading, all compilations were done for x86-64 using native
> compilers. I tested an 2.6.10rc1 based kernel with the x86-64 defconfig. 

...

I can't comment on much of anything else, but this

> The warnings from the 4.0 snapshot were pretty messed up. It always 
> printed binary garbage for function names. I assume there is already a PR
> for it.
>
> It printed a lot of new incomprehensible warnings like:
> fs/reiserfs/bitmap.c:756: warning: pointer targets in passing
> argument 1 of <garbage> Apart from being incorrect English what is
> that supposed to mean?

is definitely *not* a problem I have seen before.  Unless someone
knows better, I recommend you file a PR (with a reduced test case if
possible).  The diagnostic GCC was trying to issue is probably

 warning: pointer targets in passing argument %d of %s differ in signedness

where %d is the argument number and %s is the function name.  In the
context of kernel programming this is *probably* harmless.

I have a suspicion as to what is causing the garbage, and therefore I
suggest that you try to reproduce the problem with LANG=C and LC_ALL=C
in the environment.  Do file a PR whether or not it goes away, though.

zw