http://redhat.com/~mingo/time-warp-test/MINI-HOWTO

You can check TSC reliability on 32-bit and 64-bit x86 boxes via:

  http://people.redhat.com/mingo/time-warp-test/time-warp-test.c

On a 'good' system with perfectly in-sync TSCs you should get
output like this:

| aldebaran:~/tmp> ./time-warp-test
| 16 CPUs, running 16 parallel test-tasks.
| checking for time-warps via:
| - read time stamp counter (RDTSC) instruction (cycle resolution)
|
|  TSC: 0.42us, fail:0 /

On a 'bad' system with not-in-sync TSCs you should get output like:

| europe:~/tmp> ./time-warp-test
| 2 CPUs, running 2 parallel test-tasks.
| checking for time-warps via:
| - read time stamp counter (RDTSC) instruction (cycle resolution)
|
| new TSC-warp maximum:   -579271 cycles, 00000029861e916f -> 000000298615baa8
| new TSC-warp maximum:   -579491 cycles, 00000029862960b5 -> 0000002986208912
| new TSC-warp maximum:   -579502 cycles, 00000029865a74a4 -> 0000002986519cf6
| new TSC-warp maximum:   -579557 cycles, 000000298731ae39 -> 000000298728d654
| new TSC-warp maximum:   -579579 cycles, 000000299c72ff25 -> 000000299c6a272a
| new TSC-warp maximum:   -579601 cycles, 00000029ef2e806d -> 00000029ef25a85c
|  TSC: 0.38us, fail:25071 |

You get the 'TSC-warp' messages, and the 'fail' count is non-zero.