Walter Dnes wrote: > I've been doing a bunch of kernel-compiling recently and I've switched > between schedulers from compile to compile to compare. See > https://www.kernel.org/doc/html/v6.6/admin-guide/pm/cpufreq.html for > background info. All frequencies in khz. On my machine... > > * bios_limit == 2901000 > > * scaling_available_frequencies == 2901000 2900000 2700000 2600000 2400000 > 2300000 2100000 2000000 1800000 1700000 1500000 1400000 1200000 1100000 > 900000 800000 > > * scaling_available_governors == conservative ondemand userspace powersave > performance schedutil > NOTE: You must build the governors you want into the kernel > make menuconfig > Power management and ACPI options > CPU Frequency scaling > ...and select the desired governors. > > *YOUR NUMBERS AND GOVERNORS WILL BE DIFFERENT* When rebuilding > kernels, I wanted to do "apples-to-apples" comparisons so I would... > > * make menuconfig (in /usr/src/linux) > * cp .config .. (*VERY IMPORTANT*) > * make mrproper (initialize stuff in /usr/src/linux to a sane state) > * cp ../.config . (restore .config which got wiped by "make mrproper") > * (build new kernel, "time blah blah blah") > > I've cobbled together a bash script that can list and set cpu > frequencies and governors. Note that root or sudo permission is needed > to set anything, because the script is writing to the /sys/ filesystem. > I would hover the mouse pointer over the ICEWM toolbar CPU widget to get > CPU data. > > * select governor "userspace" and speed 2900000 > * computer "idling"; CPU speed approx 2.900 ghz and temp 28 C > * compiling kernel; CPU speed approx 2.900 ghz and temp 35-to-37 C > * kernel takes 20 minutes to build > > * select governor "schedutil" > * computer "idling"; CPU speed approx 0.800 ghz and temp 28 C > * compiling kernel; CPU speed approx 4.200 ghz and temp 46-to-48 C > * kernel takes 15 minutes to build > > Is that a dangerously high CPU temperature? Building the kernel 5 > minutes faster is a minor improvement. >
I think some CPUs can run at different temps. I'd check the specs to see what the max is. Obviously, stay away from that. I converted to F since C eludes me. It converts to about 118F. My FX-8350 during long compiles reaches 123F, sometimes 125F. I have a very large cooler on that thing and serious fans in my case. I've never worried about it even at that temp. I think mine starts to slow down at around 160F. Shutdown is a little more than that. I wouldn't want to go above 135F myself. That gives good wiggle room. I'd think that 118F is OK but it can vary from CPU to CPU. I'd check the specs for that chip and stay at least 30 degrees below that if possible. If you're using a laptop, that limits your options. A cooling pad can help and make sure the dust bunnies are blown out as well. If desktop, blow the dust bunnies out, make sure you have good case air flow and nothing is blocking the flow in or out. I tend to blow mine out twice a year, at least. The biggest thing, find out what the exact specs are for your CPU. Then go from there. That's your starting point tho. Hope that helps. Dale :-) :-)
