On Sun, 9 Sep 2007 20:17:28 +0200 (CEST) Jan Engelhardt <[EMAIL PROTECTED]> wrote:
> > On Sep 9 2007 17:49, Arjan van de Ven wrote: > >> > >> Question: Why are only Intel CPUs considered as stable? Could > >> there be implemented a more sophisticated heuristic, that actually > >> does some tests for tsc stability? > > > >on AMD multi-socket systems, afaik the tsc is not synchronized > >between packages. On Intel the tsc is derived from the FSB which is > >shared between the packages. > > Also, the TSC is not necessarily constant wrt. CPU clock speed. > If your program stalls, the core may reduce frequency and hence > TSC values are not linear to time anymore. > that depends on the CPU generation; most current cpus have constant-rate tscs (at least constant wrt their own concept of time, but at least independent of cpu frequency)... it gets more iffy on idle; on deep idle the tsc tends to stop ;( - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
