[RFC][patch] time applet execution speed

[Bernhard Fischer]

On Sat, Sep 24, 2005 at 01:33:18PM -0500, Rob Landley wrote:

>Does rdtsc work happily across scheduler invocations?

I don't see why it shouldn't. rdtsc and the PPC variant are reading
a CPU built-in timer source. It will of course wrap every now and
then, depending on your clock speed, but that's due to it being just
a 64bit counter.

Using this approach may be inadequate if you do not pin an instance and
all their children to a single CPU if you happen to be on a bigger NUMA
machine which may lack synced timers across all CPUs. On these systems
you probably wouldn't use the builtin time-calculation but would most
likely use an external tool to gather performance data. I'm not familiar
and not too concerned about that kind of setup, though.