On Tue, Sep 16, 2008 at 11:06:07AM +0200, Oliver Fromme wrote: > cpghost <cpghost_at_cordula.ws> wrote: > > On Sun, Sep 14, 2008 at 08:38:00PM -0500, Stephen Montgomery-Smith wrote: > > > I have a dual core amd64 on which I run a processor intensive numerical > > > program. I had been frustrated because it seemed to run 3 or 4 times > > > faster under Linux. But with a recent upgrade of FreeBSD-CURRENT, it > > > now goes at about the same speed as Linux. > > > > > > The program takes about an hour. For the first minute, the program runs > > > rather slowly, but then it is as if the operating system finds its way, > > > and suddenly it speeds up. "top -H" suggests that for the first minute > > > that one thread is going really slowly, and is perhaps being starved or > > > something. > > > > > > My question is - why is this happening, and is this something I should > > > expect? Are there certain switches or sysctls I can set to make it go > > > fast from the get go? > > > > It looks like you're running powerd (see in /etc/rc.conf). It can take up > > to a minute for the load average of the machine to exceed a certain > > threshold where powerd would finally bump the cpu(s) to full speed. > > No. powerd(8) does not look at the load average at all, > it looks at the CPU usage. It detects within 0.5 seconds > (the default polling interval) when the CPU usage went up > and starts adjusting the performance. It certainly doesn't > take a minute. Oh, yes, you're right: I stand corrected. powerd looks at the kern.cp_time sysctl and not at the load average. > Best regards > Oliver Thanks, -cpghost. -- Cordula's Web. http://www.cordula.ws/Received on Tue Sep 16 2008 - 11:40:08 UTC
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