Re: [PATCH] tsc-disable_B9

[Mikael Pettersson]

Alan Cox writes:
 > On Thu, 2002-08-15 at 17:56, Andrea Arcangeli wrote:
 > > sorry but I don't see the point of badtsc only in kernel.
 > > 
 > > If the TSC is bad that will be in particular bad from userspace where
 > > there's no hope to know what CPU you're running on.
 > 
 > You can still do meaningful measurements for things like profiling
 > because the cpu hop is statistically uninteresting.

There are kernel extensions around that handle process migration across
CPUs while providing virtualised per-process TSC counts, and for which
the TSCs do NOT need to be in perfect sync.

Disabling user-space RDTSC just because the TSCs aren't in sync is stupid.

/Mikael