I've been trying to understand a performance bug involving the Linux kernel. I rebuilt the MIC's kernel planning to make changes in order to explore the problem. I've used the GCC cross-compiler and sources from the MPSS distribution.
Unfortunately, when re-running my problematic scenarios on the rebuilt kernel, the performance problems become inexplicably vastly worse. Since I'm just trying to understand the problem, the performance decrease alone is not my issue: my issue is that the rebuilt kernel's behavior has changed so much from the distributed kernel's. The huge changes lead me to believe that I might be building the kernel with different options or a different compiler.
How is the distributed kernel built? Is it built with the same GCC compiler distributed with MPSS? Is it built using the same options and source provided in http://registrationcenter.intel.com/irc_nas/3778/mpss-src-3.1.2.tar ?