touch-packages team mailing list archive

[Colin Ian King <1364464@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

one of the threads to unity8-dash is creating quite a few wakeups per
second:

# eventstat 60 1

 Event/s PID   Task            Init Function             Callback
   13.02  2812 scopes_ng::Scop hrtimer_start_range_ns    hrtimer_wakeup

process 2812 is a thread of unity8-dash

attaching strace to the thread we see:

root@ubuntu-phablet:/proc# strace -p 2812 
Process 2812 attached
clock_gettime(CLOCK_MONOTONIC, {925, 47970238}) = 0
epoll_wait(57, {}, 256, 115)            = 0
clock_gettime(CLOCK_MONOTONIC, {925, 165670469}) = 0
socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0
connect(50, {sa_family=AF_LOCAL, sun_path="/run/user/32011/zmq/priv/clickscope"}, 110) = -1 ENOENT (No such file or directory)
close(50)                               = 0
clock_gettime(CLOCK_MONOTONIC, {925, 174626930}) = 0
epoll_wait(57, {}, 256, 39)             = 0
clock_gettime(CLOCK_MONOTONIC, {925, 215561930}) = 0
socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0
connect(50, {sa_family=AF_LOCAL, sun_path="/run/user/32011/zmq/priv/clickscope"}, 110) = -1 ENOENT (No such file or directory)
close(50)                               = 0
clock_gettime(CLOCK_MONOTONIC, {925, 222932007}) = 0
epoll_wait(57, {}, 256, 65)             = 0
clock_gettime(CLOCK_MONOTONIC, {925, 290266777}) = 0
socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0

..ad infinitum...

the epoll_wait() is sleeping a very short while before a connect to a
clickscope named socket path is attempted over and over again. Is this
rapid polling really necessary?   It's contributing to 0.50%-1.00% of
the CPU load of the phone.

** Affects: unity8 (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1364464

Title:
  unity8-dash has a thread that is polling rather rapidly on epoll wait

Status in “unity8” package in Ubuntu:
  New

Bug description:
  one of the threads to unity8-dash is creating quite a few wakeups per
  second:

  # eventstat 60 1

   Event/s PID   Task            Init Function             Callback
     13.02  2812 scopes_ng::Scop hrtimer_start_range_ns    hrtimer_wakeup

  process 2812 is a thread of unity8-dash

  attaching strace to the thread we see:

  root@ubuntu-phablet:/proc# strace -p 2812 
  Process 2812 attached
  clock_gettime(CLOCK_MONOTONIC, {925, 47970238}) = 0
  epoll_wait(57, {}, 256, 115)            = 0
  clock_gettime(CLOCK_MONOTONIC, {925, 165670469}) = 0
  socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
  fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
  fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0
  connect(50, {sa_family=AF_LOCAL, sun_path="/run/user/32011/zmq/priv/clickscope"}, 110) = -1 ENOENT (No such file or directory)
  close(50)                               = 0
  clock_gettime(CLOCK_MONOTONIC, {925, 174626930}) = 0
  epoll_wait(57, {}, 256, 39)             = 0
  clock_gettime(CLOCK_MONOTONIC, {925, 215561930}) = 0
  socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
  fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
  fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0
  connect(50, {sa_family=AF_LOCAL, sun_path="/run/user/32011/zmq/priv/clickscope"}, 110) = -1 ENOENT (No such file or directory)
  close(50)                               = 0
  clock_gettime(CLOCK_MONOTONIC, {925, 222932007}) = 0
  epoll_wait(57, {}, 256, 65)             = 0
  clock_gettime(CLOCK_MONOTONIC, {925, 290266777}) = 0
  socket(PF_LOCAL, SOCK_STREAM|SOCK_CLOEXEC, 0) = 50
  fcntl64(50, F_GETFL)                    = 0x2 (flags O_RDWR)
  fcntl64(50, F_SETFL, O_RDWR|O_NONBLOCK) = 0

  ..ad infinitum...

  the epoll_wait() is sleeping a very short while before a connect to a
  clickscope named socket path is attempted over and over again. Is this
  rapid polling really necessary?   It's contributing to 0.50%-1.00% of
  the CPU load of the phone.

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