Re: Measure time

From: Der Herr Hofrat (der.herr@mail.hofr.at)
Date: Wed May 08 2002 - 07:00:36 EST


> Hello!
>
> Is there any function for high precision time measuring.
> time() returns only in second. I need nanoseconds.
>
you can directly read the TSC but that will not realy give you nanoseconds
resolution as the actual read access even on a PIII/1GHz is going to take
up to a few 100 nanoseconds, and depending on what you want to time
stamp the overall jitter of that code can easaly be in the
range of a microsecond.

There are some hard-realtime patches to the Linux kernel that will
allow time precission of aprox. 1us (the TSC has a precission of 32ns)
but I don't think you can get below that without dedicated hardware.

for RTLinux check at ftp://ftp.rtlinux.org/pub/rtlinux/

hofrat
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