[coreboot] Off-topic: what's a fast, easily accessible I/O (pin)?
david.c.hubbard+coreboot at gmail.com
Thu Dec 6 04:10:01 CET 2012
On Wed, Dec 5, 2012 at 6:55 PM, Stefan Tauner
<stefan.tauner at student.tuwien.ac.at> wrote:
> if you would want to measure the instant in time you do something() in
> software with a scope or logic analyser (by toggling a pin once) on a
> typical x86 PC (e.g. pci, serial, lpt available, ok maybe not THAT
> typical anymore ;) running linux, what kind of I/O would you choose?
> latency should be minimal, but without major hardware hacks (no
> soldering to CPU pins or similar please :)
I did something similar for quantifying latency and jitter for a
control system (like a PID loop). What is your margin of error? If you
can only tolerate an error of about 1 nanosecond, you may have to take
great pains to make sure you have an accurate clock. Some physicists
had to do that to resolve their questions:
You could read from a PCI or PCI-e device and a scope or logic
analyzer on the bus would know the instant that happened.
Hope that helps,
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