Re: RELENG_13 and min cpu frequency

On 19 November 2022 8:28:45 am AEDT, mike tancsa <mike@sentex.net> wrote:

Hi mike,

 > I noticed that when I moved from an old RELENG11 to RELENG13
 > firewall, I 
 > was starting to get dropped packets.
 
excuse savage pruning; phone ...

 > e.g. printing it out every second, I see
 > 
 > while true
 > do
 > /sbin/sysctl -n dev.cpu.0.freq
 > sleep 1
 > done
 > 
 > 4308
 > 4308
 > 4308
 > 4308
 > 1902
 > 900
 > 900
 > 900
 > 4308
 > 4308
 > 4308
 > 4308
 > 4308
 > 
 >    Whats the best way to set the box NOT to scale down the CPU below
 > a 
 > certain frequency ? I want to see if not letting it drop below 3000 
 > prevents packet overruns when there is a burst of traffic from a time
 > of 
 > things being quiet ?
 > 
 > Setting debug.cpufreq.lowest: to 3000 does not seem to make a
 > difference

I see below that it's 0 .. didn't it take, or was that another time?

 > dev.cpu.0.freq_levels: 3400/-1
 > dev.cpu.0.freq: 1302

So, hmm.  powerd reads and sets values in dev.cpu.0.freq_levels, hence can't change it to anything but 3400.

So how is cpu.0.freq changing at all?  Is cpufreq using est(4)?  Are there more freqs in dev.est.0.freq_settings?

Or is it using a _relative_ driver like acpi_throttle or p4tcc?  Default /boot/device.hints has both of these disabled for good reason (Kevin Oberman can elaborate)

 > sysctl -A debug.cpufreq
 > debug.cpufreq.verbose: 0
 > debug.cpufreq.lowest: 0
 > 
 > 
 > CPU is CPU: Intel(R) Xeon(R) E-2226G CPU @ 3.40GHz
 > (3400.00-MHz K8-class CPU)

Also noted that the usual +1 freq for turbo mode isn't there.  Strange?  (I don't speak Xeon though)

cheers, Ian