Subject: Re: [linux-audio-dev] high-res time measurement?
From: Paul Davis (paul_AT_linuxaudiosystems.com)
Date: Fri May 30 2003 - 02:05:48 EEST
> In my host, I would like to be able to measure how much time each
>individual LADPSA plugin takes. Assuming I do realtime work with the
>smallest buffer sizes my system can handle, what options are available
>to me to measure time on this small scale? I know that the typical
>system calls time and gettimeofday have resolution of 10 ms, which is
no, gettimeofday() has microsecond resolution. on a PII-450, it takes
about 60usec to call gettimeofday(), and about 12usec to execute
inline code to read the cycle counter and then divide by a
pre-established CPU MHz. its really a lot simpler to use
getttimeofday(), but JACK (http://jackit.sf.net/) has generic code to
read the cycle timer and figure out the CPU MHz if you want to go down
that path.
>too big for this purpose. Is there any way to do this? Is there a
>high-res time howto?
no howto. most kernel people try to discourage it with claims about
unreliability.
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