On Fri, Jun 14, 2024 at 11:54:52AM +0100, Michael wrote > I would think 46-48°C is refreshingly cool, but it very much depends > on the CPU chip, the MoBo and its BIOS/microcode settings.
I looked up my CPU (see my reply to Dale). The max temp allowed is 71.3 C. A short kernel compile is one thing. I tried schedutil during an emerge world update, and the temp was hitting 70 C. Ouch! schedutil has to go. > I recall an early i7 CPU laptop would not go above 2,400MHz when > 4core/8threads were running, but on single core processes I would > see it on i7z jumping up to 4,200MHz. Speaking of cores+threads... I had always thought my cpu had 12 cores. i.e. /proc/cpuinfo showed 12 "cpus" as did directory /sys/devices/system/cpu/ But I was wrong. The specs show 6 real cores, plus hyperthreading. See Greg Kroah-Hartman's presentation about the security issue called "hyperthreading"... https://events19.linuxfoundation.org/wp-content/uploads/2018/07/gregkh_mds.pdf Read it and weep. Page 6 summarizes it succinctly... ================================================== OpenBSD was right * Guessed more problems would be in this area * Disabled SMT for Intel chips in June 2018 * Repeated the plea to disable this in August 2018 * Prevented almost all MDS issues automatically * Security over performance * Huge respect! ================================================== I immediately went into the BIOS and disabled hyperthreading... and adjusted makeopts in make.conf <G> > What do you get when you run make with '-j jobs', where jobs=max > threads of your CPU? I hadn't realized that this applied to kernel compiling as well as portage "emerge". Since my system now shows 6 (real) cores, I set 5 jobs. My /usr/src/makeover script is now... =========================================================== #!/bin/bash make -j 5 && \ make modules_install && \ cp arch/x86_64/boot/bzImage /boot/vmlinuz-experimental && \ cp System.map /boot/System.map-experimental && \ cp .config /boot/config-experimental =========================================================== Since I wanted to exorcise schedutil from my system, I had an excuse to run another compile. From /usr/src/linux I executed... cp .config .. make mrproper cp ../.config . time ../makeover I had manually selected "userspace" and 2900000 khz. The result was so farcical, I repeated it a second time to confirm it was for real. real 4m43.120s user 20m11.003s sys 1m25.728s. Under 5 minutes. Like wow! The CPU stayed pegged at around 2.900 Ghz and the temperature never got over 47 C. Thank you very much for that info about jobs for make. -- Roses are red Roses are blue Depending on their velocity Relative to you
