Re: [PATCH -v2] perf, x86: try to handle unknown nmis with running perfctrs

Peter Zijlstra
2010-08-16T19:13:30Z

On Mon, 2010-08-16 at 23:06 +0400, Cyrill Gorcunov wrote:
> I never heard of backward running tsc, though tsc is a strange beast.
>
Its not supposed to happen, but then there's BIOS failure-add that frobs
the TSC from SMIs and fun TSC artifacts around CPU frequency changes and
people resetting TSC in S-states etc..

In short, never trust the TSC to be even remotely sane.