From: Joerg Roedel This patch simplifies the get_cycles_sync() function by removing the #ifdefs from it. Further it introduces an optimization for AMD processors. There the RDTSCP instruction is used instead of CPUID;RDTSC which is helpfull if the kernel runs as a KVM guest. Running as a guest makes CPUID very expensive because it causes an intercept of the guest. Signed-off-by: Joerg Roedel -- Joerg Roedel Operating System Research Center AMD Saxony LLC & Co. KG