Thomas29/11/2013 13:25, Monjalon : > 29/11/2013 14:53, Dmitry Vyal : > > On 11/28/2013 03:01 PM, Richardson, Bruce wrote: > > > [BR] Frequency changes should not affect timers for modern Intel CPUs. > > > > The error frequency greatly reduces if I patch > > loop limit as I described earlier or if I call rte_power_init and > > rte_power_freq_max as Thomas suggested. > > > > But the only way to get rid of them completely is to set performance > > governor. > > Please check that your hardware do not support invariant TSC. > It would explain why you need to fix frequency. > > I attach a simple code to test CPU feature "Invariant TSC".
Note that this feature is called constant_tsc in /proc/cpuinfo: grep --color -m1 constant_tsc /proc/cpuinfo It is checked by check_tsc_flags() at DPDK initialization and should print a warning if missing: http://dpdk.org/browse/dpdk/commit/?id=e7c8996e13b9abb706ea0de53271346f4f86ca03 -- Thomas