Date: Mon, 21 Nov 2022 14:08:02 -0500 From: mike tancsa <mike@sentex.net> To: FreeBSD Questions <freebsd-questions@freebsd.org>, Ian Smith <smithi@nimnet.asn.au>, Kevin Oberman <rkoberman@gmail.com> Subject: Re: RELENG_13 and min cpu frequency Message-ID: <f5b51083-4bc4-2ee2-befd-b2356a781189@sentex.net> In-Reply-To: <9d17ea30-4b10-2aa3-9d09-017da7423844@sentex.net> References: <9d17ea30-4b10-2aa3-9d09-017da7423844@sentex.net>
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On 11/18/2022 4:28 PM, mike tancsa wrote: > I noticed that when I moved from an old RELENG11 to RELENG13 firewall, > I was starting to get dropped packets. Looking at when it was > happening, it actually seems to happen at times where the network load > is really low?!?! When I see a high PPS or high bandwidth, I dont get > overruns on the nic. Trying to figure out whats going on, it seems to > correlate with when the CPU reduces its frequency to save on power. > When its in turbo mode, it scales up to 4300, but then in the quiet > hours, it goes down to 800 and that seems to be when I start getting > the odd overrun. > OK, some possible progress. I noticed that sysctl -a dev.cpufreq.0.freq_driver dev.cpufreq.0.freq_driver: hwpstate_intel0 Looking at the man page dev.hwpstate_intel.%d.epp Energy/Performance Preference. Valid values range from 0 to 100. Setting this field conveys a hint to the hardware regarding a preference towards performance (at value 0), energy efficiency (at value 100), or somewhere in between. it defaults to 50. I changed the value to 5 sysctl -w dev.hwpstate_intel.0.epp=5 Looking at the freq value dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 dev.cpu.0.freq: 4410 Should have a better sense in a couple of days ---Mike > 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 > > dev.cpu.0.cx_method: C1/hlt > dev.cpu.0.cx_usage_counters: 229391593 > dev.cpu.0.cx_usage: 100.00% last 87us > dev.cpu.0.cx_lowest: C1 > dev.cpu.0.cx_supported: C1/1/0 > dev.cpu.0.freq_levels: 3400/-1 > dev.cpu.0.freq: 1302 > dev.cpu.0.temperature: 43.0C > dev.cpu.0.coretemp.throttle_log: 0 > dev.cpu.0.coretemp.tjmax: 100.0C > dev.cpu.0.coretemp.resolution: 1 > dev.cpu.0.coretemp.delta: 57 > dev.cpu.0.%parent: acpi0 > dev.cpu.0.%pnpinfo: _HID=none _UID=0 _CID=none > dev.cpu.0.%location: handle=\_SB_.PR00 > dev.cpu.0.%driver: cpu > dev.cpu.0.%desc: ACPI CPU > > 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) > >
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