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[173.242.120.104]) by smtp.gmail.com with ESMTPSA id v68-20020a626147000000b0052f39a877d8sm392006pfb.65.2022.08.07.00.03.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Aug 2022 00:03:22 -0700 (PDT) Date: Sun, 7 Aug 2022 15:03:18 +0800 From: Leo Yan To: carsten.haitzler@foss.arm.com Cc: linux-kernel@vger.kernel.org, coresight@lists.linaro.org, suzuki.poulose@arm.com, mathieu.poirier@linaro.org, mike.leach@linaro.org, linux-perf-users@vger.kernel.org, acme@kernel.org Subject: Re: [PATCH v5 14/14] perf test: Add relevant documentation about CoreSight testing Message-ID: <20220807070318.GL34254@leoy-ThinkPad-X240s> References: <20220728145256.2985298-1-carsten.haitzler@foss.arm.com> <20220728145256.2985298-15-carsten.haitzler@foss.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220728145256.2985298-15-carsten.haitzler@foss.arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Thu, Jul 28, 2022 at 03:52:56PM +0100, carsten.haitzler@foss.arm.com wrote: > From: "Carsten Haitzler (Rasterman)" > > 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 > --- > .../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 > + :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. > + 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/ > +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: Reviewed-by: Leo Yan > @@ -0,0 +1,5 @@ > +Arm CoreSight Support > +===================== > + > +For full documentation, see Documentation/trace/coresight/coresight-perf.rst > +in the kernel tree. > -- > 2.32.0 >