-fprofile-generate and -fprofile-use

[Kelley Cook]

> I started with a clean slate in my build environment 
> and did not have any residual files hanging around. 
> Are the steps I have indicated in my earlier email 
> correct. Is there a way I can break down the problem 
> into a smaller sub-set of flags and eliminate the flag 
> causing the performance problem. What I mean is since 
> -fprofile-generate and -fprofile-use enable a bunch of 
> flags, would it make sense to avoid profiling and try 
> out some of the individual flags on a trial and error 
> basis. If so what would be the flags to start the 
> trials with.
> 
> -girish

Before we go any farther, are you sure that you are also turning on optimization with -fprofile-generate and -fprofile-use?

In other words, you aren't just using "gcc -fprofile-generate xxx.c" to create your object files are you?

You need to use something like "gcc -O2 -march=pentium4 -fprofile-generate" as unoptimized profiles are pretty pointless.

Instead of general terms, specific examples would help a lot.  Like a link to your code that is having problems.

Kelley Cook