> what's the point of setting CONFIG_HZ=1000 with it? Agreed, if you go "tickless", you want to go to the lowest value for what's still ticking: I have my own

> what's the point of setting CONFIG_HZ=1000 with it? Agreed, if you go "tickless", you want to go to the lowest value for what's still ticking: I have my own kernel configs, and I generally use HZ=100: # zcat /proc/config.gz |grep HZ_ CONFIG_NO_HZ_COMMON=y # CONFIG_HZ_PERIODIC is not set # CONFIG_NO_HZ_IDLE is not set CONFIG_NO_HZ_FULL=y CONFIG_HZ_100=y # CONFIG_HZ_250 is not set # CONFIG_HZ_300 is not set # CONFIG_HZ_1000 is not set CONFIG_MACHZ_WDT=m For Little.Big heterogeneous cores (like on the i7-1270P Alder Lake P), I suggest also thinking about how the cores are arranged to group the interrupts intelligently, and not just go by which cores are efficiency/power as /usr/local/bin/coretype simply reports: P CORES: 0..7 E Cores: 8..19 You should check which cores are on a core.id with: cat /proc/cpuinfo |egrep "physical|core.id|cache.size|processor" |grep -E "core.id|processor" On my cpu: processor : 0 core id : 0 processor : 1 core id : 0 processor : 2 core id : 4 processor : 3 core id : 4 processor : 4 core id : 8 processor : 5 (....) Therefore you could want to: - Leave efficiency cores 8..19 as-is (nohz_full is not ideal and consumes power, leave the efficiency cores alone - they are made to be efficient!) - Use power core 0 as normal - Put all the other power cores 1-7 but 4 in NOHZ_FULL - Put all IRQ and callbacks on power core cpu 4: for performance + a race to sleep So on my i7-1270P, I use: `nohz_full=1-3,5-7 rcu_nocbs=0-3,5-7 irqaffinity=4` In theory, you get the best of both worlds. In practice, unfortunately, it's not perfect as the NVMe and WIFI drivers require extra care or they'll sprinkle interrupts everywhere which you can check with just cat /proc/interrupts For NVMe, you can limit the queues for nocbs with `nvme.poll_queues=1 nvme.write_queues=1` For wifi, you can try to limit its eagerness to have more interrupts with a simple script like `for irq in $(grep -v " ...: ......... 0 0 0 ......... 0 0 0 0 0 0 0 0 0 0 0" /proc/interrupts |sed -e 's/:.//g' -e 's/^ //g' -e 's/ .//g' |grep -v '^$') do [ -f /proc/irq/$irq/smp_affinity_list ] \ && echo 4 > /proc/irq/$irq/smp_affinity_list \ || echo skipping $irq done` BTW, if you have more IO and you prefer having interrupts spread a little more, you can use both cores one of the avx512-less efficiency core.id 8 with irqaffinity=4-5 Then the cmdline becomes: cpu0_hotplug nohz_full=1-3,5-7 nr_running=1 rcu_nocbs=0-3,6-7 irqaffinity=4-5 EDIT: I added some clarifications, it's very late but I realized it required a little more context