On Thu 24-02-22 12:30:47, Dirk Müller wrote:
Hi Jiri,
Am Do., 24. Feb. 2022 um 10:30 Uhr schrieb Jiri Slaby
: Historically, you wanted the lowest good value for power savings.
I think that was before HZ_IDLE functionality, but I might be wrong.
And the highest possible for preemption (best user response feeling).
it's not only that, it is also affecting resolution / granularity of a lot of things.
Yes, but that goes both ways. E.g. some kernel tunables are in milliseconds and translated to jiffies internally. So if I previously was setting 4/8 ms in those settings, it was 1 or 2 jiffies. Now it will be again 1 or 2 jiffies but resulting in delays of 3.3 and 6.6 ms instead. So the change will have subtle impact on various things in user setups.
I actually don't care about what value is selected. But you should get in touch with timer guys and the performance team too. I doubt they read this list :). But they should definitely comment (provided we unify kernels with SLE). So maybe creating a bug?
Who are the "timer guys" and why are they not subscribed to the kernel list? ;)
I can create a bugreport if thats the preferred way to come to a decision.
Yeah, let's track this in bugzilla both for the sake of documentation of
the decision as well as having some place to track various impacts we
find the change has. Please add kernel-performance-bugs@suse.de to CC for
performance team awareness... Thanks!
Honza
--
Jan Kara