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Clarify section about broken performance counters on i.MX6

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The performance counters are broken on most (all?) i.MX6 boards, not
only on the ones from Boundary Devices.

Task-number: QTBUG-56769
Change-Id: I9e0f291be7e00df3d9d1b98c7414dfd37e265b39
Reviewed-by: Kari Hormi <kari.hormi@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
This commit is contained in:
Ulf Hermann
2016-10-31 14:23:05 +01:00
parent 4325f4facb
commit d012e3e4bd
1 changed files with 5 additions and 5 deletions
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10
doc/src/analyze/cpu-usage-analyzer.qdoc
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@@ -346,11 +346,11 @@
\li Some versions of Perf will not start recording unless given a \li Some versions of Perf will not start recording unless given a
certain minimum sampling frequency. Try with a certain minimum sampling frequency. Try with a
\uicontrol {Sampling Frequency} of 1000. \uicontrol {Sampling Frequency} of 1000.
\li On some devices, for example Boundary Devices i.MX6 Boards, the \li On some devices, in particular various i.MX6 Boards, the hardware
Perf support is not very stable and the Linux kernel may randomly performance counters are dysfunctional and the Linux kernel may
fail to record data after some time. Perf can use different types randomly fail to record data after some time. Perf can use different
of events to trigger samples. You can get a list of available event types of events to trigger samples. You can get a list of available
types by running \c {perf list} on the device and add event types by running \c {perf list} on the device and add
\c {-e <event type>} to the \uicontrol {Additional arguments} field \c {-e <event type>} to the \uicontrol {Additional arguments} field
to change the event type to be used. The choice of event type to change the event type to be used. The choice of event type
affects the performance and stability of the sampling. affects the performance and stability of the sampling.