Accuracy of rte_get_tsc_hz() compared to linux

[Isaac Boukris]

On an older laptop (i7-8650U), running fedora with kernel 6.8.9-100.fc38.x86_64

journalctl -b | grep -i tsc
Aug 29 12:34:00 localhost.localdomain kernel: tsc: Detected 2100.000
MHz processor
Aug 29 12:34:00 localhost.localdomain kernel: tsc: Detected 2099.944 MHz TSC
Aug 29 12:34:00 localhost.localdomain kernel: TSC deadline timer available
Aug 29 12:34:00 localhost.localdomain kernel: clocksource: tsc-early:
mask: 0xffffffffffffffff max_cycles: 0x1e44fb6c2ab, max_idle_ns:
440795206594 ns
Aug 29 12:34:00 localhost.localdomain kernel: clocksource: Switched to
clocksource tsc-early
Aug 29 12:34:00 localhost.localdomain kernel: tsc: Refined TSC
clocksource calibration: 2112.000 MHz

sudo bpftrace -e 'BEGIN { printf("%u\n", *kaddr("tsc_khz")); exit(); }'
Attaching 1 probe...
2112000

dpdk logs before lowering the rounding:

EAL: TSC frequency arch ~0 KHz
EAL: TSC frequency linux ~2110000 KHz
EAL: TSC frequency estimate ~2110000 KHz

after lowering the rounding to 1KHz:

EAL: TSC frequency arch ~0 KHz
EAL: TSC frequency linux ~2112000 KHz
EAL: TSC frequency estimate ~2112949 KHz