Unity8 wakes up continuously at around 62Hz on an idle desktop

Bug #1664828 reported by Daniel van Vugt on 2017-02-15
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Canonical System Image
Undecided
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The Ubuntu Power Consumption Project
Undecided
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qtmir (Ubuntu)
Undecided
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unity8 (Ubuntu)
Medium
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Bug Description

eventstat showing two unity8 threads on an idle desktop:

 Event/s PID Task Init Function Callback
   62.00 12359 QSGRenderThread do_nanosleep hrtimer_wakeup
   62.00 11858 unity8 schedule_hrtimeout_range_ hrtimer_wakeup

Although it's not calling swap buffers or rendering anything (confirmed by MIR_CLIENT_PERF_REPORT=log). Just waking up at around the same frequency as the screen (although 62Hz is more like every 16.0ms, unlike the screen's 16.68ms/59.95Hz)

description: updated
description: updated
Daniel van Vugt (vanvugt) wrote :

Maybe related:

/usr/share/unity8/Components/ScrollCalculator.qml: interval: 16

description: updated
Daniel van Vugt (vanvugt) wrote :

We do implement this in QtMir, which might also be related:

http://doc.qt.io/qt-5/qscreen.html#refreshRate-prop

Daniel van Vugt (vanvugt) wrote :

Spinning the QSGRenderThread at this frequency could easily explain bug 1664160 too...

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