The signal number must be unused by the program under normal operation. Internally it acts as a switch, triggered by the signal, which is off by default. In your code, bracket the code you want profiled in calls to ProfilerStart and ProfilerStop. ProfilerStart will take the profile-filename as an argument. In Linux 2. For security reasons, CPU profiling will not write to a file -- and is thus not usable -- for setuid programs. It has many output modes, both textual and graphical. Some give just raw numbers, much like the -pg output of gcc , and others show the data in the form of a dependency graph.
It also requires dot to be installed for any of the graphical output routines, and gv to be installed for --gv mode described below. Use kcachegrind to analyze your callgrind output:. The cost is specified in 'hits', i. The 'calls' from function a to b record how many times function b was found in the stack traces directly below function a. Tip: if you use a debug build the output will include file and line number information and kcachegrind will show an annotated source code view.
In the various graphical modes of pprof, the output is a call graph annotated with timing information, like so:. Each node represents a procedure. The directed edges indicate caller to callee relations. Each node is formatted as follows:. The last one or two lines contains the timing information.
The profiling is done via a sampling method, where by default we take samples a second. Therefor one unit of time in the output corresponds to about 10 milliseconds of execution time.
The "local" time is the time spent executing the instructions directly contained in the procedure and in any other procedures that were inlined into the procedure. The "cumulative" time is the sum of the "local" time and the time spent in any callees. If the cumulative time is the same as the local time, it is not printed.
The size of the node is proportional to the local count. The percentage displayed in the node corresponds to the count divided by the total run time of the program that is, the cumulative count for main. An edge from one node to another indicates a caller to callee relationship. Any solution? Thanks a lot,. Improve this question. Vu Nguyen Vu Nguyen 11 3 3 bronze badges.
Add a comment. Active Oldest Votes. Improve this answer. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The heap checker may mischaracterize some memory accesses in libraries listed after it on the link line. For instance, it may report these libraries as leaking memory when they're not. See the source code for more details.
Furthermore, if you do fork, and the child calls exit , it may corrupt the profile data. We hope to have a fix for both problems in the next release of perftools hopefully perftools 1. These are in addition to the environment variables you can set at runtime to affect tcmalloc, described below. Thus, there's no harm in linking -lprofiler into every application, and also -ltcmalloc assuming you're ok using the non-libc malloc library.
The easiest way to turn them on is by setting the appropriate environment variables. The second compares tcmalloc to win32's malloc. The perftools configure script can't always detect this kind of case, leading to that error.
Neither issue should affect the core tcmalloc library; they both affect the perftools tools such as cpu-profiler, heap-checker, and heap-profiler.
This bug should not affect tcmalloc, but may cause occasional deadlock with the cpu-profiler, heap-profiler, and heap-checker. Its likeliness increases the more dlopen commands an executable has. Most executables don't have any, though several library routines like getgrgid call dlopen behind the scenes.
I'll explain the problem first, and then some workarounds. If you do not turn on cpu-profiling, you shouldn't see any crashes due to perftools. The gory details: The underlying problem is in the backtrace function, which is a built-in function in libc.
Backtracing is fairly straightforward in the normal case, but can run into problems when having to backtrace across a signal frame. Unfortunately, the cpu-profiler uses signals in order to register a profiling event, so every backtrace that the profiler does crosses a signal frame. The solution: The dwarf debugging format has support for 'cfi annotations', which make it easy to recognize a signal frame.
Some OS distributions, such as Fedora and gentoo A future version of libunwind should recognize these annotations; these systems should not see any crashes.
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