Re: AMD X2 unsynced TSC fix?

Christoph Lameter
2006-10-30T20:31:28Z

On Fri, 27 Oct 2006, thockin@hockin.org wrote:

> Wrong, too. We have a patch that will be coming SOON (trust me, I am
> pushing hard for the author to publish it). With this patch applied you
> should never see the TSC go backwards. Period. It should be monotonic
> (to userspace, kernel rdtsc calls can still be wrong). CPUs should stay
> very nearly in sync (again, to userspace). The overhead of this patch is
> pretty minimal and costs nothing unless you actually read the TSC.

Well why not use regular clock_gettime() instead? If you add code for TSC
processing (intercepting RDTSC from user space???) then it may be
comparable in performance to time retrieval via POSIX calls using
vsyscalls. Look like you may start duplicating the time subsystem?