[PATCH v6 00/17] coresight: Use per-sink trace ID maps for Perf sessions
Suzuki K Poulose
suzuki.poulose at arm.com
Fri Jul 26 07:26:04 PDT 2024
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
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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