On Fri, 1 Jan 2016, Mike Galbraith wrote:
> On Thu, 2015-12-31 at 10:24 -0600, Clark Williams wrote:
> > I pulled this update and tried it on my laptop (i7 quad-core with HT)
> > and an Atom testbox. I'm seeing a change in the cpu utilization of
> > ksoftirqd between 4.1.15-rt17 and 4.4-rc2-rt1, where the per-cpu
> > ksoftirqd threads are running at between 25-40% utilization:
> >
> > top - 10:15:57 up 13:46, 2 users, load average: 9.44, 9.30, 8.93
> > Tasks: 188 total, 2 running, 186 sleeping, 0 stopped, 0 zombie
> > %Cpu(s): 4.7 us, 53.6 sy, 0.0 ni, 37.4 id, 0.1 wa, 0.0 hi, 4.2 si,
> > 0.0 st
> > KiB Mem : 4046064 total, 480548 free, 179528 used, 3385988 buff/cache
> > KiB Swap: 5177340 total, 5169908 free, 7432 used. 3785624 avail Mem
> >
> > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> >
> > 3 root -2 0 0 0 0 S 37.3 0.0 307:52.44
> > ksoftirqd/0
> > 32 root -2 0 0 0 0 S 37.3 0.0 308:08.72
> > ksoftirqd/2
> > 42 root -2 0 0 0 0 R 37.3 0.0 308:32.84
> > ksoftirqd/3
> > 22 root -2 0 0 0 0 S 26.9 0.0 222:29.82
> > ksoftirqd/1
> > 1 root 20 0 46628 6980 4976 S 1.3 0.2 0:13.98 systemd
> >
> > 22358 williams 20 0 159980 4552 3780 R 1.0 0.1 0:00.39 top
> >
>
> Heh, I didn't notice immediately because I throttle nohz, am seeing
> only tiny utilization (but nohz idle isn't working). With throttle
> patch removed, box is screaming, expires=4294990471 pokes eyeball.
>
> swapper 0 [003] 392.708321: timer:hrtimer_cancel:
> hrtimer=0xffff88041ecce720
> swapper 0 [003] 392.708321: timer:hrtimer_start:
> hrtimer=0xffff88041ecce720 function=tick_sched_timer/0x0 expires=4294990471
> softexpires=4294990471
There is a major hickup in the hrtimer RT conversion. I'll have a look next
week.
Thanks,
tglx
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