Re: [Valgrind-users] Application doesn't leak memory running valgrind

[Stefano A. <san...@al...>]

On Mon, 2022-02-28 at 13:11 -0800, Stefano Antonelli wrote:
> When the leak occurs, the number of 4k pages owned by this render
> device increases.  Running valgrind leak-test (or gdb with malloc
> breakpoint), the number of 4k pages owned by this render device _do
> not_ increase.

When I run callgrind, the same behaviour happens.

valgrind  --tool=callgrind --instr-atstart=no ./qml-mwe3

Once the application is up and running, I use:

:~# callgrind_control --instr=on 4120
PID 4120: ./qml-mwe3
sending command instrumentation on to pid 4120
  OK.
:~# callgrind_control -s 4120
PID 4120: ./qml-mwe3
sending command status internal to pid 4120
  Number of running threads: 4, thread IDs: 1 2 3 4
  Events collected: Ir
  Functions: 1,104 (executed 1,289, contexts 1,104)
  Basic blocks: 1,816 (executed 1,120,586,516, call sites 452)

:~# callgrind_control --instr=off 4120
PID 4120: ./qml-mwe3
sending command instrumentation off to pid 4120
  OK.

After the I turn on the instrumentation, the display stops updating
completely (it's running an animation).  Once I turn off the
instrumentation, the display resumes.  I would expect the animation to
run dreadfully slow, but not freeze in place for the duration of time
instrumentation was on.  I don't know exactly how much time this was,
but if I had to guess I'd say around 10 minutes.

I should also add that the processor is armhf and I noticed with
callgrind I get a couple of warnings:

==4120== Callgrind, a call-graph generating cache profiler
==4120== Copyright (C) 2002-2017, and GNU GPL'd, by Josef Weidendorfer
et al.
==4120== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright
info
==4120== Command: ./qml-mwe3
==4120== 
==4120== For interactive control, run 'callgrind_control -h'.
==4120== Warning: noted but unhandled ioctl 0x6443 with no
size/direction hints.
==4120==    This could cause spurious value errors to appear.
==4120==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing
a proper wrapper.
==4120== Warning: noted but unhandled ioctl 0x4b51 with no
size/direction hints.
==4120==    This could cause spurious value errors to appear.
==4120==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing
a proper wrapper.
disInstr(thumb): unhandled instruction: 0xDEFF 0xF8DD

I don't know if that's breaking things or not.  Nor do I know what
these IOCTLs are, but I am trying to
parse README_MISSING_SYSCALL_OR_IOCTL as I go along here.

-Stef