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
swapper 0 [003] 392.708323: timer:hrtimer_cancel:
hrtimer=0xffff88041ecce720
swapper 0 [003] 392.708324: timer:hrtimer_expire_entry:
hrtimer=0xffff88041ecce720 now=392697118535 function=tick_sched_timer/0x0
swapper 0 [003] 392.708325: timer:hrtimer_expire_exit:
hrtimer=0xffff88041ecce720
swapper 0 [003] 392.708326: timer:hrtimer_start:
hrtimer=0xffff88041ecce720 function=tick_sched_timer/0x0 expires=392700750000
softexpires=392700750000
swapper 0 [003] 392.708328: timer:tick_stop: success=yes msg=
swapper 0 [003] 392.708329: timer:hrtimer_cancel:
hrtimer=0xffff88041ecce720
swapper 0 [003] 392.708329: timer:hrtimer_start:
hrtimer=0xffff88041ecce720 function=tick_sched_timer/0x0 expires=4294990471
softexpires=4294990471
swapper 0 [003] 392.708331: timer:hrtimer_cancel:
hrtimer=0xffff88041ecce720
swapper 0 [003] 392.708332: timer:hrtimer_expire_entry:
hrtimer=0xffff88041ecce720 now=392697126313 function=tick_sched_timer/0x0
swapper 0 [003] 392.708333: timer:hrtimer_expire_exit:
hrtimer=0xffff88041ecce720
swapper 0 [003] 392.708334: timer:hrtimer_start:
hrtimer=0xffff88041ecce720 function=tick_sched_timer/0x0 expires=392700750000
softexpires=392700750000
swapper 0 [003] 392.708336: timer:tick_stop: success=yes msg=
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