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Message-ID: <ZqOzio8Oco9ZFsDm@x1> Date: Fri, 26 Jul 2024 11:32:42 -0300 From: Arnaldo Carvalho de Melo <acme@...nel.org> To: Suzuki K Poulose <suzuki.poulose@....com> Cc: James Clark <james.clark@...aro.org>, coresight@...ts.linaro.org, gankulkarni@...amperecomputing.com, mike.leach@...aro.org, leo.yan@...ux.dev, anshuman.khandual@....com, James Clark <james.clark@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>, Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, "Liang, Kan" <kan.liang@...ux.intel.com>, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-stm32@...md-mailman.stormreply.com, linux-perf-users@...r.kernel.org Subject: Re: [PATCH v6 00/17] coresight: Use per-sink trace ID maps for Perf sessions On Fri, Jul 26, 2024 at 03:26:04PM +0100, Suzuki K Poulose wrote: > Hi Arnaldo > > On 26/07/2024 15:18, Arnaldo Carvalho de Melo wrote: > > On Mon, Jul 22, 2024 at 11:11:42AM +0100, James Clark wrote: > > > This will allow sessions with more than CORESIGHT_TRACE_IDS_MAX ETMs > > > as long as there are fewer than that many ETMs connected to each sink. > > > > Hey, may I take the tools part, i.e. patches 0-7 and someone on the ARM > > kernel team pick the driver bits? > > I plan to pick the kernel driver bits for v6.12 Perhaps it is better for me to wait for that? - Arnaldo > Kind regards > Suzuki > > > > > - Arnaldo > > > Each sink owns its own trace ID map, and any Perf session connecting to > > > that sink will allocate from it, even if the sink is currently in use by > > > other users. This is similar to the existing behavior where the dynamic > > > trace IDs are constant as long as there is any concurrent Perf session > > > active. It's not completely optimal because slightly more IDs will be > > > used than necessary, but the optimal solution involves tracking the PIDs > > > of each session and allocating ID maps based on the session owner. This > > > is difficult to do with the combination of per-thread and per-cpu modes > > > and some scheduling issues. The complexity of this isn't likely to worth > > > it because even with multiple users they'd just see a difference in the > > > ordering of ID allocations rather than hitting any limits (unless the > > > hardware does have too many ETMs connected to one sink). > > > > > > Per-thread mode works but only until there are any overlapping IDs, at > > > which point Perf will error out. Both per-thread mode and sysfs mode are > > > left to future changes, but both can be added on top of this initial > > > implementation and only sysfs mode requires further driver changes. > > > > > > The HW_ID version field hasn't been bumped in order to not break Perf > > > which already has an error condition for other values of that field. > > > Instead a new minor version has been added which signifies that there > > > are new fields but the old fields are backwards compatible. > > > > > > Changes since v5: > > > * Hide queue number printout behind -v option > > > * Style change in cs_etm__process_aux_output_hw_id() > > > * Move new format enum to an earlier commit to reduce churn > > > > > > Changes since v4: > > > > > > * Fix compilation failure when TRACE_ID_DEBUG is set > > > * Expand comment about not freeing individual trace IDs in > > > free_event_data() > > > > > > Changes since v3: > > > > > > * Fix issue where trace IDs were overwritten by possibly invalid ones > > > by Perf in unformatted mode. Now the HW_IDs are also used for > > > unformatted mode unless the kernel didn't emit any. > > > * Add a commit to check the OpenCSD version. > > > * Add a commit to not save invalid IDs in the Perf header. > > > * Replace cs_etm_queue's formatted and formatted_set members with a > > > single enum which is easier to use. > > > * Drop CORESIGHT_TRACE_ID_UNUSED_FLAG as it's no longer needed. > > > * Add a commit to print the queue number in the raw dump. > > > * Don't assert on the number of unformatted decoders if decoders == 0. > > > > > > > > > Changes since v2: > > > > > > * Rebase on coresight-next 6.10-rc2 (b9b25c8496). > > > * Fix double free of csdev if device registration fails. > > > * Fix leak of coresight_trace_id_perf_start() if trace ID allocation > > > fails. > > > * Don't resend HW_ID for sink changes in per-thread mode. The existing > > > CPU field on AUX records can be used to track this instead. > > > * Tidy function doc for coresight_trace_id_release_all() > > > * Drop first two commits now that they are in coresight-next > > > * Add a commit to make the trace ID spinlock local to the map > > > > > > Changes since V1: > > > > > > * Rename coresight_device.perf_id_map to perf_sink_id_map. > > > * Instead of outputting a HW_ID for each reachable ETM, output > > > the sink ID and continue to output only the HW_ID once for > > > each mapping. > > > * Keep the first two Perf patches so that it applies cleanly > > > on coresight-next, although they have been applied on perf-tools-next > > > * Add new *_map() functions to the trace ID public API instead of > > > modifying existing ones. > > > * Collapse "coresight: Pass trace ID map into source enable" into > > > "coresight: Use per-sink trace ID maps for Perf sessions" because the > > > first commit relied on the default map being accessible which is no > > > longer necessary due to the previous bullet point. > > > > > > > > > James Clark (17): > > > perf: cs-etm: Create decoders after both AUX and HW_ID search passes > > > perf: cs-etm: Allocate queues for all CPUs > > > perf: cs-etm: Move traceid_list to each queue > > > perf: cs-etm: Create decoders based on the trace ID mappings > > > perf: cs-etm: Only save valid trace IDs into files > > > perf: cs-etm: Support version 0.1 of HW_ID packets > > > perf: cs-etm: Print queue number in raw trace dump > > > perf: cs-etm: Add runtime version check for OpenCSD > > > coresight: Remove unused ETM Perf stubs > > > coresight: Clarify comments around the PID of the sink owner > > > coresight: Move struct coresight_trace_id_map to common header > > > coresight: Expose map arguments in trace ID API > > > coresight: Make CPU id map a property of a trace ID map > > > coresight: Use per-sink trace ID maps for Perf sessions > > > coresight: Remove pending trace ID release mechanism > > > coresight: Emit sink ID in the HW_ID packets > > > coresight: Make trace ID map spinlock local to the map > > > > > > drivers/hwtracing/coresight/coresight-core.c | 37 +- > > > drivers/hwtracing/coresight/coresight-dummy.c | 3 +- > > > .../hwtracing/coresight/coresight-etm-perf.c | 43 +- > > > .../hwtracing/coresight/coresight-etm-perf.h | 18 - > > > .../coresight/coresight-etm3x-core.c | 9 +- > > > .../coresight/coresight-etm4x-core.c | 9 +- > > > drivers/hwtracing/coresight/coresight-priv.h | 1 + > > > drivers/hwtracing/coresight/coresight-stm.c | 3 +- > > > drivers/hwtracing/coresight/coresight-sysfs.c | 3 +- > > > .../hwtracing/coresight/coresight-tmc-etr.c | 5 +- > > > drivers/hwtracing/coresight/coresight-tmc.h | 5 +- > > > drivers/hwtracing/coresight/coresight-tpdm.c | 3 +- > > > .../hwtracing/coresight/coresight-trace-id.c | 138 ++-- > > > .../hwtracing/coresight/coresight-trace-id.h | 70 +- > > > include/linux/coresight-pmu.h | 17 +- > > > include/linux/coresight.h | 21 +- > > > tools/build/feature/test-libopencsd.c | 4 +- > > > tools/include/linux/coresight-pmu.h | 17 +- > > > tools/perf/Makefile.config | 2 +- > > > tools/perf/arch/arm/util/cs-etm.c | 11 +- > > > .../perf/util/cs-etm-decoder/cs-etm-decoder.c | 49 +- > > > .../perf/util/cs-etm-decoder/cs-etm-decoder.h | 3 +- > > > .../util/cs-etm-decoder/cs-etm-min-version.h | 13 + > > > tools/perf/util/cs-etm.c | 629 +++++++++++------- > > > tools/perf/util/cs-etm.h | 12 +- > > > 25 files changed, 650 insertions(+), 475 deletions(-) > > > create mode 100644 tools/perf/util/cs-etm-decoder/cs-etm-min-version.h > > > > > > -- > > > 2.34.1
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