Commit 8e058ee3 authored by Ulf Hermann's avatar Ulf Hermann

Doc: The perf profiler can now unwind JavaScript

... with certain quirks.

Change-Id: I3192853caf978a50cbf05adc039b5704a955f05c
Reviewed-by: Riitta-Leena Miettinen's avatarLeena Miettinen <riitta-leena.miettinen@qt.io>
parent a246e432
......@@ -245,13 +245,21 @@
functions that spend the most CPU time most prominently.
If a function without debug information is encountered, further unwinding
of the stack may fail. Unwinding will also fail if a QML or JavaScript
function is encountered, and for some symbols implemented in assembler. If
unwinding fails, only part of the call chain is displayed, and the
surrounding functions may seem to be interrupted. This does not necessarily
mean they were actually interrupted during the execution of the
application, but only that they could not be found in the stacks where the
unwinding failed.
of the stack may fail. Unwinding will also fail for some symbols
implemented in assembly language. If unwinding fails, only a part of the
call chain is displayed, and the surrounding functions may seem to be
interrupted. This does not necessarily mean they were actually interrupted
during the execution of the application, but only that they could not be
found in the stacks where the unwinding failed.
JavaScript functions from the QML engine running in the JIT mode can be
unwound. However, their names will only be displayed when
\c QV4_PROFILE_WRITE_PERF_MAP is set. Compiled JavaScript generated by the
\l{http://doc.qt.io/QtQuickCompiler/}{Qt Quick Compiler} can also be
unwound. In this case the C++ names generated by the compiler are shown for
JavaScript functions, rather than their JavaScript names. When running in
interpreted mode, stack frames involving QML can also be unwound, showing
the interpreter itself, rather than the interpreted JavaScript.
Kernel functions included in call chains are shown on the third row of each
thread. All kernel functions are summarized and not differentiated any
......
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