Subject: Re: timing issue
To: None <firstname.lastname@example.org>
From: Manuel Badzong <email@example.com>
Date: 11/26/2006 02:40:49
Chuck Swiger wrote:
> What does everybody have their scheduler quantum set to (kern.hz or
> maybe kern.clockrate sysctl?) set to?
> If HZ=100, it's possibly reasonable for the process to not be able to
> sleep and have the kernel return to the process in less than one
> quantum, aka 10 ms. It might be the case that setting the scheduler
> to HZ=1000 will significantly improve the observed latency for this test.
Sorry, I was a few days off. Anyway, thanks for all the answers.
For the archives: After recompiling the Kernel with HZ=1000 the latency
dropped below 1ms (exactly like FreeBSD 6.1, which uses a default
clockrate of 1000 Hz). The new output of timing.c looks like:
timeout: 1000 usec
gettimeofday: 2.5 usec
nanosleep: 1996.9 usec
usleep: 1997.4 usec
select: 1998.3 usec