ResolutionThat's incorrect to compare Redhat's SMP kernel with Virtuozzo SMP kernel just because they were built using different configuration options.
This performance difference is caused by so called 4GB/4GB split feature
which is on by default in Virtuoozzo SMP kernel while RedHat ships it only
in bigmem kernel. This feature results in bigger system call overhead and as a
result in worse overall performance. Redhat's SMP kernel also includes support of PAE (Physical Address Extension) which is disabled in Virtuozzo SMP kernel.
It would be correct to compare Redhat's SMP kernel with Virtuozzo entnosplit one or Redhat's bigmem kernel with Virtuozzo enterprise one because these pairs have similar configuration.
This article briefly describes different types of Virtuozzo kernels available for installation.