Optimization for Newer Processors

[Tim Prince]

Tim Prince wrote:
> Brian McGrew wrote:
>>  We¹re currently compiling
>> with gcc-4.1.1 using the following optimization flags on Fedora Core 5 using
>> a 2.6.16.16 kernel.  As it happens, the code runs seemlessly on CentOS 5.2
>> with a 2.6.18 kernel as well.  Upgrading compilers, if there is a compelling
>> reason is an option for us.  Upgrading kernels, at this time is not an
>> option because of 3rd party hardware support.
>>
> Basically, you seem to be saying that the old scheduler doesn't work well
> for you, while the newer one is OK. That's not under the control of gcc.
> You didn't say whether you set the NUMA option in BIOS.  If you wish to
> run with NUMA, so as to get the advantage of local memory access, and want
> high level affinity control from gcc, you might upgrade to a gcc version
> which supports libgomp, use OpenMP directives in the important code
> sections, and set the GOMP_CPU_AFFINITY.
Of course, if taskset isn't working for you on FC5, GOMP_CPU_AFFINITY may
not work either.