Hi Willy, On Wed, Jan 31, 2024 at 6:39 PM Willy Tarreau <w@xxxxxx> wrote: > On Wed, Jan 31, 2024 at 05:46:48PM +0100, Geert Uytterhoeven wrote: > > When working on SoC bring-up, (a full) userspace may not be available, > > making it hard to benchmark the CPU performance of the system under > > development. Still, one may want to have a rough idea of the (relative) > > performance of one or more CPU cores, especially when working on e.g. > > the clock driver that controls the CPU core clock(s). > > > > Hence add the CPU MHz benchmark test[1], which estimates the clock > > frequency of the CPU core it is running on, and make it available as a > > Linux kernel test module. > > > > When built-in, this benchmark can be run without any userspace present. > > That's a great idea, I never thought about turning it into a module! > > > Parallel runs (run on multiple CPU cores) are supported, just kick the > > "run" file multiple times. > > Hmmm does it mean it will run on the CPU that writes this "run" ? > Because this could allow one to start tests using e.g.: > > taskset -c $CPU tee /sys/.../run <<< y That does indeed work. > But we could also wonder if it wouldn't be easier to either send "y" > to /sys/.../cpu0/run or may just send the CPU number to "run" instead > of "y". That would complicate the code a lot. > In my experience with this tool, you most always want to easily > control the CPU number because SoCs these days are not symmetrical at > all. That's why it prints the CPU number ;-) On multi-core systems, you can also do e.g. for i in $(seq $(nproc)); do echo yes > /sys/module/test_mhz/parameters/run & done and collect the results for all CPU cores. BTW, this is the same for test_dhry. > Another point is that it would be nice if there was a way to present > the result in a form that a script can retrieve from the directory, > maybe the last measurement or something like this. I know that scripts > are commonly used to check for a machine's correct behavior, and I try > to encourage users to verify that it's working well, so anything we can > do that makes it easier to use would be welcome. I'll give that a try... > But overall, I like it! You've got my ack. Thanks! > Hmmm I don't know if this is intended, the SPDX tag says MIT but the > MODULE_LICENSE at the top says MIT/GPL. I can't say I care that much but > I preferred to report it in case it's an accident ;-) That must be an oversight. I'll change the SPDX-License-Identifier to "GPL-2.0 OR MIT". Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds