On Sun, 2006-11-26 at 00:16 -0800, Wink Saville wrote: > Robert Hancock wrote: > >>>> Actually, we need to ask the CPU/System makers to provide a system wide > > Generally user mode code should just be using gettimeofday. When the TSC > > is usable as a sane time source, the kernel will use it. When it's not, > > it will use something else like the HPET, ACPI PM Timer or (at last > > resort) the PIT, in increasing degrees of slowness. > > > > But gettimeofday is much too expensive compared to RDTSC.
it's the cost of a syscall (1000 cycles?) plus what it takes to get a reasonable time estimate. Assuming your kernel has enough time support AND your tsc is reasonably ok, it'll be using that. If it's NOT using that then that's a pretty good sign that you can't also use it in userspace.... -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - 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/