Red Hat Enterprise Linux TSC work has proven that there is a definite need for using a fast time source such as TSC amongst enterprise Linux customers. The fact of the matter is that TSC was never designed to be used as a time source with multi-processor systems. However, customers are interested in using TSC as the time source to perform the time sensitive operations and at the same time desire scalable solutions.

Next generation AMD processors will provide a TSC that is P-state and C-State invariant, which will make the TSC immune to drift. Applications will then be able to use TSC as the time source without any need for custom engineering work described in this article. At the same time the Linux community is working on a per-CPU TSC solution that will keep track of each core's TSC frequency.

Bhavana Nagendra is a Member of AMD's technical staff supporting Red Hat Enterprise Linux on the AMD Opteron™ processor platform. She has worked extensively on TSC drift solutions in RHEL along with her colleague Mark Langsdorf who authored the RHEL4 TSCnow! patch, in collaboration with Red Hat development and performance teams.