On 2021/06/07 06:54, Thomas Hartwig wrote:
Hi,
for some reason PREEMPT is configured for 250? Am I missing something or is it by error?
$: grep CONFIG_HZ /boot/config-5.3.18-lp152.75-preempt # CONFIG_HZ_PERIODIC is not set # CONFIG_HZ_100 is not set CONFIG_HZ_250=y # CONFIG_HZ_300 is not set # CONFIG_HZ_1000 is not set CONFIG_HZ=250
----- # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set && # CONFIG_HZ_100 is not set # CONFIG_HZ_250 is not set # CONFIG_HZ_300 is not set CONFIG_HZ_1000=y CONFIG_HZ=1000 CONFIG_SCHED_HRTICK=y --- Have always leaned toward 1kHz, it divides a bunch of ways. I went with the voluntary preempt, thought max latency in no preempt might make some things shudder, while my linux box really is more akin to a server and thought voluntary preemption might be sufficient. Haven't ever noticed downsides. Ya know, Opensuse does ship their src packages for kernels, you could always build a kernel from one of those. I like the idea of knowing what's in my kernel. I have a script to pull down latest patches from kernel.org for latest stable and I build from those patches/deltas Saves about 80% in disk space with the # kernel sources I keep around. I'd have to say building a kernel is one of the easier jobs you could try. Once you've got a build for your machine, you could even go for booting directly from disk...but takes a bit of bravery. But still if you use a currently running kernel as base sample of what drivers need to be included, its not that difficult to do.
Thomas
On 6/7/21 3:00 PM, Takashi Iwai wrote:
Well, if HZ=1000 really helps, it implies that it's no requirement of the hard RT, and kernel-preempt flavor would work enough for that purpose.
AFAIK, kernel-preempt is available for Leap. And for TW, we're going to switch to the dynamic preempt, i.e. the preemption model is chosen via boot option.
Takashi