Public bug reported:
I noticed that systemd on my idle Wily desktop is creating very short
lived threads at 1Hz. While these aren't doing much, it still consumes
power doing wakeups to create these periodic threads.
Showing thread creation with forkstat:
$ sudo forkstat
Time Event PID Info Duration Process
13:43:07 clone 1 parent /sbin/init splash
13:43:07 clone 7483 thread /sbin/init splash
13:43:07 exit 7483 0 0.001 /sbin/init splash
13:43:08 clone 1 parent /sbin/init splash
13:43:08 clone 7484 thread /sbin/init splash
13:43:08 exit 7484 0 0.000 /sbin/init splash
13:43:10 clone 1 parent /sbin/init splash
13:43:10 clone 7485 thread /sbin/init splash
13:43:10 exit 7485 0 0.000 /sbin/init splash
13:43:11 clone 1 parent /sbin/init splash
13:43:11 clone 7486 thread /sbin/init splash
13:43:11 exit 7486 0 0.000 /sbin/init splash
13:43:12 clone 1 parent /sbin/init splash
13:43:12 clone 7487 thread /sbin/init splash
13:43:12 exit 7487 0 0.000 /sbin/init splash
13:43:13 clone 1 parent /sbin/init splash
13:43:13 clone 7488 thread /sbin/init splash
13:43:13 exit 7488 0 0.000 /sbin/init splash
13:43:15 clone 1 parent /sbin/init splash
13:43:15 clone 7489 thread /sbin/init splash
13:43:15 exit 7489 0 0.000 /sbin/init splash
13:43:16 clone 1 parent /sbin/init splash
13:43:16 clone 7490 thread /sbin/init splash
13:43:16 exit 7490 0 0.000 /sbin/init splash
13:43:17 clone 1 parent /sbin/init splash
13:43:17 clone 7491 thread /sbin/init splash
13:43:17 exit 7491 0 0.000 /sbin/init splash
And it's consuming some cycles over time:
$ sudo perf stat -p 1
^C
Performance counter stats for process id '1':
7.519868 task-clock (msec) # 0.000 CPUs utilized
41 context-switches # 0.005 M/sec
39 cpu-migrations # 0.005 M/sec
3 page-faults # 0.399 K/sec
12,107,977 cycles # 1.610 GHz
10,597,101 stalled-cycles-frontend # 87.52% frontend cycles
idle
0 stalled-cycles-backend # 0.00% backend cycles
idle
2,285,818 instructions # 0.19 insns per cycle
# 4.64 stalled cycles per
insn
457,133 branches # 60.790 M/sec
69,444 branch-misses # 15.19% of all branches
46.099593011 seconds time elapsed
The thread is just doing the following:
clock_gettime(0x7 /* CLOCK_??? */, {52592, 947682919}) = 0
read(14, "\1\0\0\0\0\0\0\0", 8) = 8
fcntl(30, F_DUPFD_CLOEXEC, 3) = 15
ioctl(30, 0xc0189374, 0x7ffeaf311470) = 0
fcntl(16, F_GETFD) = 0x1 (flags FD_CLOEXEC)
clone(Process 7466 attached
child_stack=0x7f97c3580e30,
flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
parent_tidptr=0x7f97c35819d0, tls=0x7f97c3581700, child_tidptr=0x7f97c35819d0)
= 7466
[pid 7466] set_robust_list(0x7f97c35819e0, 24) = 0
[pid 1] timerfd_settime(14, TFD_TIMER_ABSTIME, {it_interval={0, 0},
it_value={52594, 197493000}}, NULL <unfinished ...>
[pid 7466] ioctl(15, 0xc018937c <unfinished ...>
[pid 1] <... timerfd_settime resumed> ) = 0
[pid 7466] <... ioctl resumed> , 0x7f97c3580d60) = -1 EAGAIN (Resource
temporarily unavailable)
[pid 1] epoll_wait(4, <unfinished ...>
[pid 7466] close(15) = 0
[pid 7466] close(16) = 0
[pid 7466] madvise(0x7f97c2d81000, 8368128, MADV_DONTNEED) = 0
[pid 7466] _exit(0) = ?
[pid 7466] +++ exited with 0 +++
<... epoll_wait resumed> {{EPOLLIN, {u32=3, u64=3}}}, 34, -1) = 1
** Affects: systemd (Ubuntu)
Importance: Undecided
Status: New
** Summary changed:
- systemd on wily desktop generating short lived threads every second in a
quite system
+ systemd on wily desktop generating short lived threads every second in a
quiet system
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Desktop Bugs, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1470845
Title:
systemd on wily desktop generating short lived threads every second in
a quiet system
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