Messages in this thread | | | From | Mike Leach <> | Date | Thu, 11 Aug 2022 14:03:23 +0100 | Subject | Re: [PATCH v5 14/14] perf test: Add relevant documentation about CoreSight testing |
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On Wed, 10 Aug 2022 at 18:59, Carsten Haitzler <carsten.haitzler@foss.arm.com> wrote: > > > > On 8/7/22 08:03, Leo Yan wrote: > > On Thu, Jul 28, 2022 at 03:52:56PM +0100, carsten.haitzler@foss.arm.com wrote: > >> From: "Carsten Haitzler (Rasterman)" <raster@rasterman.com> > >> > >> Add/improve documentation helping people get started with CoreSight and > >> perf as well as describe the testing and how it works. > >> > >> Cc: linux-doc@vger.kernel.org > >> Signed-off-by: Carsten Haitzler <carsten.haitzler@arm.com> > >> --- > >> .../trace/coresight/coresight-perf.rst | 160 ++++++++++++++++++ > >> tools/perf/Documentation/arm-coresight.txt | 5 + > >> 2 files changed, 165 insertions(+) > >> create mode 100644 Documentation/trace/coresight/coresight-perf.rst > >> create mode 100644 tools/perf/Documentation/arm-coresight.txt > >> > >> diff --git a/Documentation/trace/coresight/coresight-perf.rst b/Documentation/trace/coresight/coresight-perf.rst > >> new file mode 100644 > >> index 000000000000..401a097aea4b > >> --- /dev/null > >> +++ b/Documentation/trace/coresight/coresight-perf.rst > >> @@ -0,0 +1,160 @@ > >> +.. SPDX-License-Identifier: GPL-2.0 > >> + > >> +================ > >> +CoreSight - Perf > >> +================ > >> + > >> + :Author: Carsten Haitzler <carsten.haitzler@arm.com> > >> + :Date: June 29th, 2022 > >> + > >> +Perf is able to locally access CoreSight trace data and store it to the > >> +output perf data files. This data can then be later decoded to give the > >> +instructions that were traced for debugging or profiling purposes. You > >> +can log such data with a perf record command like:: > >> + > >> + perf record -e cs_etm//u testbinary > >> + > >> +This would run some test binary (testbinary) until it exits and record > >> +a perf.data trace file. That file would have AUX sections if CoreSight > >> +is working correctly. You can dump the content of this file as > >> +readable text with a command like:: > >> + > >> + perf report --stdio --dump -i perf.data > >> + > >> +You should find some sections of this file have AUX data blocks like:: > >> + > >> + 0x1e78 [0x30]: PERF_RECORD_AUXTRACE size: 0x11dd0 offset: 0 ref: 0x1b614fc1061b0ad1 idx: 0 tid: 531230 cpu: -1 > >> + > >> + . ... CoreSight ETM Trace data: size 73168 bytes > >> + Idx:0; ID:10; I_ASYNC : Alignment Synchronisation. > >> + Idx:12; ID:10; I_TRACE_INFO : Trace Info.; INFO=0x0 { CC.0 } > >> + Idx:17; ID:10; I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0x0000000000000000; > >> + Idx:26; ID:10; I_TRACE_ON : Trace On. > >> + Idx:27; ID:10; I_ADDR_CTXT_L_64IS0 : Address & Context, Long, 64 bit, IS0.; Addr=0x0000FFFFB6069140; Ctxt: AArch64,EL0, NS; > >> + Idx:38; ID:10; I_ATOM_F6 : Atom format 6.; EEEEEEEEEEEEEEEEEEEEEEEE > >> + Idx:39; ID:10; I_ATOM_F6 : Atom format 6.; EEEEEEEEEEEEEEEEEEEEEEEE > >> + Idx:40; ID:10; I_ATOM_F6 : Atom format 6.; EEEEEEEEEEEEEEEEEEEEEEEE > >> + Idx:41; ID:10; I_ATOM_F6 : Atom format 6.; EEEEEEEEEEEN > >> + ... > >> + > >> +If you see these above, then your system is tracing CoreSight data > >> +correctly. > >> + > >> +To compile perf with CoreSight support in the tools/perf directory do:: > >> + > >> + make CORESIGHT=1 > >> + > >> +This requires OpenCSD to build. You may install distribution packages > >> +for the support such as libopencsd and libopencsd-dev or download it > >> +and build yourself. Upstream OpenCSD is located at: > >> + > >> + https://github.com/Linaro/OpenCSD > >> + > >> +For complete information on building perf with CoreSight support and > >> +more extensive usage look at: > >> + > >> + https://github.com/Linaro/OpenCSD/blob/master/HOWTO.md > >> + > >> + > >> +Kernel CoreSight Support > >> +------------------------ > >> + > >> +You will also want CoreSight support enabled in your kernel config. > >> +Ensure it is enabled with:: > >> + > >> + CONFIG_CORESIGHT=y > >> + > >> +There are various other CoreSight options you probably also want > >> +enabled like:: > >> + > >> + CONFIG_CORESIGHT_LINKS_AND_SINKS=y > >> + CONFIG_CORESIGHT_LINK_AND_SINK_TMC=y > >> + CONFIG_CORESIGHT_CATU=y > >> + CONFIG_CORESIGHT_SINK_TPIU=y > >> + CONFIG_CORESIGHT_SINK_ETBV10=y > >> + CONFIG_CORESIGHT_SOURCE_ETM4X=y > >> + CONFIG_CORESIGHT_STM=y > >> + CONFIG_CORESIGHT_CPU_DEBUG=y > > > > So far CORESIGHT_STM and CORESIGHT_CPU_DEBUG are irrelevant with perf > > recording. Perf only creates path from source (ETM) to sink (TMC-ETR > > or TMC-ETF), so it's good to drop them. > > will do. > > >> + CONFIG_CORESIGHT_CTI=y > >> + CONFIG_CORESIGHT_CTI_INTEGRATION_REGS=y > >> + > >> +Please refer to the kernel configuration help for more information. > >> + > >> +Perf test - Verify kernel and userspace perf CoreSight work > >> +----------------------------------------------------------- > >> + > >> +When you run perf test, it will do a lot of self tests. Some of those > >> +tests will cover CoreSight (only if enabled and on ARM64). You > >> +generally would run perf test from the tools/perf directory in the > >> +kernel tree. Some tests will check some internal perf support like: > >> + > >> + Check Arm CoreSight trace data recording and synthesized samples > >> + Check Arm SPE trace data recording and synthesized samples > >> + > >> +Some others will actually use perf record and some test binaries that > >> +are in tests/shell/coresight and will collect traces to ensure a > >> +minimum level of functionality is met. The scripts that launch these > >> +tests are in the same directory. These will all look like: > >> + > >> + CoreSight / ASM Pure Loop > >> + CoreSight / Memcpy 16k 10 Threads > >> + CoreSight / Thread Loop 10 Threads - Check TID > >> + etc. > >> + > >> +These perf record tests will not run if the tool binaries do not exist > >> +in tests/shell/coresight/*/ and will be skipped. If you do not have > >> +CoreSight support in hardware then either do not build perf with > >> +CoreSight support or remove these binaries in order to not have these > >> +tests fail and have them skip instead. > >> + > >> +These tests will log historical results in the current working > >> +directory (e.g. tools/perf) and will be named stats-\*.csv like: > >> + > >> + stats-asm_pure_loop-out.csv > >> + stats-memcpy_thread-16k_10.csv > >> + ... > >> + > >> +These statistic files log some aspects of the AUX data sections in > >> +the perf data output counting some numbers of certain encodings (a > >> +good way to know that it's working in a very simple way). One problem > >> +with CoreSight is that given a large enough amount of data needing to > >> +be logged, some of it can be lost due to the processor not waking up > >> +in time to read out all the data from buffers etc.. You will notice > >> +that the amount of data collected can vary a lot per run of perf test. > >> +If you wish to see how this changes over time, simply run perf test > >> +multiple times and all these csv files will have more and more data > >> +appended to it that you can later examine, graph and otherwise use to > >> +figure out if things have become worse or better. > >> + > >> +This means sometimes these tests fail as they don't capture all the > >> +data needed. This is about tracking quality and amount of data > >> +produced over time and to see when changes to the Linux kernel improve > >> +quality of traces. > >> + > >> +Be aware that some of these tests take quite a while to run, specifically > >> +in processing the perf data file and dumping contents to then examine what > >> +is inside. > >> + > >> +You can change where these csv logs are stored by setting the > >> +PERF_TEST_CORESIGHT_STATDIR environment variable before running perf > >> +test like:: > >> + > >> + export PERF_TEST_CORESIGHT_STATDIR=/var/tmp > >> + perf test > >> + > >> +They will also store resulting perf output data in the current > >> +directory for later inspection like:: > >> + > >> + perf-asm_pure_loop-out.data > >> + perf-memcpy_thread-16k_10.data > >> + ... > >> + > >> +You can alter where the perf data files are stored by setting the > >> +PERF_TEST_CORESIGHT_DATADIR environment variable such as:: > >> + > >> + PERF_TEST_CORESIGHT_DATADIR=/var/tmp > >> + perf test > >> + > >> +You may wish to set these above environment variables if you whish to > > > > s/whish/wish/ > > good catch. :) > > >> +keep the output of tests outside of the current working directory for > >> +longer term storage and examination. > >> diff --git a/tools/perf/Documentation/arm-coresight.txt b/tools/perf/Documentation/arm-coresight.txt > >> new file mode 100644 > >> index 000000000000..c117fc50a2a9 > >> --- /dev/null > >> +++ b/tools/perf/Documentation/arm-coresight.txt > > > > You could see we have a document perf-arm-spe.txt, for alignment it's > > good to rename this file as perf-arm-coresight.txt. > > > > The rest of this patch is good for me, with addressing the above minor > > comments: > > will do. > > > Reviewed-by: Leo Yan <leo.yan@linaro.org> > > > > > >> @@ -0,0 +1,5 @@ > >> +Arm CoreSight Support > >> +===================== > >> + > >> +For full documentation, see Documentation/trace/coresight/coresight-perf.rst > >> +in the kernel tree. > >> -- > >> 2.32.0 > >>
Reviewed-by: Mike Leach <mike.leach@linaro.org> -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK
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