| 2012-02-27 10:15:54 |
Colin Ian King |
description |
I've observed that gvfs-afc-volume-monitor is polling at ~1Hz stat'ing /var/run/usbmuxd
Using eventstat from my PPA: https://launchpad.net/~colin-king/+archive/powermanagement as follows one can identify the thread that is waking up every second:
sudo eventstat 1 1 | grep gvfs-afc
1.00 2027 gvfs-afc-volume hrtimer_start_range_ns hrtimer_wakeup
and a strace shows:
stat("/var/run/usbmuxd", 0x7faf78339cd0) = -1 ENOENT (No such file or directory)
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7faf78339dd0) = 0
stat("/var/run/usbmuxd", 0x7faf78339cd0) = -1 ENOENT (No such file or directory)
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0},
Rather than continually polling for /var/run/usbmuxd it is more efficient to use inotify on /var/rub and observe any new files appearing and then do the check for /var/run/usbmuxd
Frequent periodical polling reads on the filesystem waste power and reduce the running time on battery. |
I've observed that gvfs-afc-volume-monitor is polling at ~1Hz stat'ing /var/run/usbmuxd
Using eventstat from my PPA: https://launchpad.net/~colin-king/+archive/powermanagement as follows one can identify the thread that is waking up every second:
sudo eventstat 1 1 | grep gvfs-afc
1.00 2027 gvfs-afc-volume hrtimer_start_range_ns hrtimer_wakeup
and a strace shows:
stat("/var/run/usbmuxd", 0x7faf78339cd0) = -1 ENOENT (No such file or directory)
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7faf78339dd0) = 0
stat("/var/run/usbmuxd", 0x7faf78339cd0) = -1 ENOENT (No such file or directory)
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0},
Rather than continually polling for /var/run/usbmuxd it is more efficient to use inotify on /var/run and observe any new files appearing and then do the check for /var/run/usbmuxd
Frequent periodical polling reads on the filesystem waste power and reduce the running time on battery. |
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