diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2023-01-12 16:20:13 +0100 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2023-01-16 10:14:12 -1000 |
| commit | 5584e2dbe8c9c95ceb178786fb88e5edf625e1b6 (patch) | |
| tree | 6b117636e203be8e4246aa30704d784243e4deee /docs | |
| parent | 7c10cb38ccb86a0e56fff32bb348aa4b34e17e10 (diff) | |
| download | qemu-5584e2dbe8c9c95ceb178786fb88e5edf625e1b6.zip qemu-5584e2dbe8c9c95ceb178786fb88e5edf625e1b6.tar.gz qemu-5584e2dbe8c9c95ceb178786fb88e5edf625e1b6.tar.bz2 | |
tcg: add perfmap and jitdump
Add ability to dump /tmp/perf-<pid>.map and jit-<pid>.dump.
The first one allows the perf tool to map samples to each individual
translation block. The second one adds the ability to resolve symbol
names, line numbers and inspect JITed code.
Example of use:
perf record qemu-x86_64 -perfmap ./a.out
perf report
or
perf record -k 1 qemu-x86_64 -jitdump ./a.out
DEBUGINFOD_URLS= perf inject -j -i perf.data -o perf.data.jitted
perf report -i perf.data.jitted
Co-developed-by: Vanderson M. do Rosario <vandersonmr2@gmail.com>
Co-developed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230112152013.125680-4-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/devel/tcg.rst | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/docs/devel/tcg.rst b/docs/devel/tcg.rst index 136a7a0..b4096a1 100644 --- a/docs/devel/tcg.rst +++ b/docs/devel/tcg.rst @@ -188,3 +188,26 @@ memory areas instead calls out to C code for device emulation. Finally, the MMU helps tracking dirty pages and pages pointed to by translation blocks. +Profiling JITted code +--------------------- + +The Linux ``perf`` tool will treat all JITted code as a single block as +unlike the main code it can't use debug information to link individual +program counter samples with larger functions. To overcome this +limitation you can use the ``-perfmap`` or the ``-jitdump`` option to generate +map files. ``-perfmap`` is lightweight and produces only guest-host mappings. +``-jitdump`` additionally saves JITed code and guest debug information (if +available); its output needs to be integrated with the ``perf.data`` file +before the final report can be viewed. + +.. code:: + + perf record $QEMU -perfmap $REMAINING_ARGS + perf report + + perf record -k 1 $QEMU -jitdump $REMAINING_ARGS + DEBUGINFOD_URLS= perf inject -j -i perf.data -o perf.data.jitted + perf report -i perf.data.jitted + +Note that qemu-system generates mappings only for ``-kernel`` files in ELF +format. |