CoreSight

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2768 discussions

[PATCH v3 0/4] coresight: Do not call smp_processor_id from preemptible contexts

by Suzuki K Poulose

We have a few places where we call smp_processor_id() from preemptible contexts during the perf buffer handling. We do this to figure out the numa node for the allocation in case the event is not CPU bound. Use numa_node_id() instead in such cases to avoid a splat. Changes since V2: - Use NUMA_NO_NODE instead of numa_node_id() for event->cpu == -1. (Robin Murphy) Suzuki K Poulose (4): coresight: tmc-etr: Do not call smp_processor_id() from preemptible coresight: tmc-etr: alloc_perf_buf: Do not call smp_processor_id from preemptible coresight: tmc-etf: Do not call smp_processor_id from preemptible coresight: etb10: Do not call smp_processor_id from preemptible drivers/hwtracing/coresight/coresight-etb10.c | 6 ++---- drivers/hwtracing/coresight/coresight-tmc-etf.c | 6 ++---- drivers/hwtracing/coresight/coresight-tmc-etr.c | 13 ++++--------- 3 files changed, 8 insertions(+), 17 deletions(-) -- 2.7.4

7 years

[PATCH v4 00/30] coresight: Support for ACPI bindings

by Suzuki K Poulose

This series adds the support for CoreSight devices on ACPI based platforms. The device connections are encoded as _DSD graph property[0], with CoreSight specific extensions to indicate the direction of data flow as described in [1]. Components attached to CPUs are listed as child devices of the corresponding CPU, removing explicit links to the CPU like we do in the DT. The majority of the series cleans up the driver and prepares the subsystem for platform agnostic firwmare probing, naming scheme, searching etc. We introduce platform independent helpers to parse the platform supplied information. Thus we rename the platform handling code from: of_coresight.c => coresight-platform.c The CoreSight driver creates shadow devices that appear on the Coresight bus, in addition to the real devices (e.g, AMBA bus devices). The name of these devices match the real device. This makes the device name a bit cryptic for ACPI platform. So this series also introduces a generic platform agnostic device naming scheme for the shadow Coresight devices. Towards this we also make changes to the way we lookup devices to resolve the connections, as we can't use the names to identify the devices. So, we use the "fwnode_handle" of the real device for the device lookups. Towards that we clean up the drivers to keep track of the "CoreSight" device rather than the "real" device. However, all real operations, like DMA allocation, Power management etc. must be performed on the real device which is the parent of the shadow device. Finally we add the support for parsing the ACPI platform data. The power management support is missing in the ACPI (and this is not specific to CoreSight). The firmware must ensure that the respective power domains are turned on. Applies on v5.2-rc1 Tested on a Juno-r0 board with ACPI bindings patch (Patch 31/30) added on top of [2]. You would need to make sure that the debug power domain is turned on before the Linux kernel boots. (e.g, connect the DS-5 to the Juno board while at UEFI). arm32 code is only compile tested. [0] ACPI Device Graphs using _DSD (Not available online yet, approved but awaiting publish and eventually should be linked at). https://uefi.org/sites/default/files/resources/_DSD-implementation-guide-to… [1] https://developer.arm.com/docs/den0067/latest/acpi-for-coresighttm-10-platf… [2] https://github.com/tianocore/edk2-platforms.git Changes since v3: - Add tags from Mathieu Changes since v2: - Fix the symlink name for ETM devices under cs_etm PMU (Patch by Mathieu) - Drop patches merged already in the tree. - Add the tags from Mathieu - More documentation with examples of ACPI graph in ACPI bindings support. - Fix ETM4 error return path (Mathieu) - Drop the patches exposing device links via sysfs, to be posted as separate series. - Drop the generic helper for device search by fwnode for a better cleanup later. - Split the ACPI bindings support patch for AMBA and platform devices. - Return integer error for <platform>_get_platform_data() helpers. - Fix comment about the return code for acpi_get_coresight_cpu(). - Ensure we don't have devices part of multiple graphs (Mathieu). Changes since v1: [ http://lists.infradead.org/pipermail/linux-arm-kernel/2019-March/639963.html ] - Dropped the replicator driver merge changes as they were pulled already. - Cleanups for Power management in the drivers. - Reuse platform description for connection information. Also introduce routines to clean up the platform description to make sure we drop the references (fwnode_handle). - Add RFC patches for exposing the device-links via sysfs. - Drop tracking the device in favour of coresight_device. - Name etb10 as "etb" - Fix other comments in v1. - Use a generic helper for searching with fwnode_handle rather than adding one for CoreSight. Mathieu Poirier (1): coresight: Use coresight device names for sinks in PMU attribute Suzuki K Poulose (29): coresight: funnel: Clean up device book keeping coresight: replicator: Cleanup device tracking coresight: tmc: Clean up device specific data coresight: catu: Cleanup device specific data coresight: tpiu: Clean up device specific data coresight: stm: Cleanup device specific data coresight: etm: Clean up device specific data coresight: etb10: Clean up device specific data coresight: Rename of_coresight to coresight-platform coresight: etm3x: Rearrange cp14 access detection coresight: stm: Rearrange probing the stimulus area coresight: tmc-etr: Rearrange probing default buffer size coresight: platform: Make memory allocation helper generic coresight: Make sure device uses DT for obsolete compatible check coresight: Introduce generic platform data helper coresight: Make device to CPU mapping generic coresight: Remove cpu field from platform data coresight: Remove name from platform description coresight: Cleanup coresight_remove_conns coresight: Reuse platform data structure for connection tracking coresight: Rearrange platform data probing coresight: Add support for releasing platform specific data coresight: platform: Use fwnode handle for device search coresight: Use fwnode handle instead of device names coresight: Use platform agnostic names coresight: stm: ACPI support for parsing stimulus base coresight: Support for ACPI bindings coresight: acpi: Support for AMBA components coresight: acpi: Support for platform devices drivers/acpi/acpi_amba.c | 9 + drivers/hwtracing/coresight/Makefile | 3 +- drivers/hwtracing/coresight/coresight-catu.c | 40 +- drivers/hwtracing/coresight/coresight-catu.h | 1 - drivers/hwtracing/coresight/coresight-cpu-debug.c | 3 +- drivers/hwtracing/coresight/coresight-etb10.c | 51 +- drivers/hwtracing/coresight/coresight-etm-perf.c | 8 +- drivers/hwtracing/coresight/coresight-etm.h | 6 +- .../hwtracing/coresight/coresight-etm3x-sysfs.c | 12 +- drivers/hwtracing/coresight/coresight-etm3x.c | 45 +- drivers/hwtracing/coresight/coresight-etm4x.c | 37 +- drivers/hwtracing/coresight/coresight-etm4x.h | 2 - drivers/hwtracing/coresight/coresight-funnel.c | 35 +- drivers/hwtracing/coresight/coresight-platform.c | 810 +++++++++++++++++++++ drivers/hwtracing/coresight/coresight-priv.h | 4 + drivers/hwtracing/coresight/coresight-replicator.c | 42 +- drivers/hwtracing/coresight/coresight-stm.c | 118 ++- drivers/hwtracing/coresight/coresight-tmc-etf.c | 9 +- drivers/hwtracing/coresight/coresight-tmc-etr.c | 44 +- drivers/hwtracing/coresight/coresight-tmc.c | 96 +-- drivers/hwtracing/coresight/coresight-tmc.h | 2 - drivers/hwtracing/coresight/coresight-tpiu.c | 24 +- drivers/hwtracing/coresight/coresight.c | 164 ++++- drivers/hwtracing/coresight/of_coresight.c | 297 -------- include/linux/coresight.h | 61 +- 25 files changed, 1332 insertions(+), 591 deletions(-) create mode 100644 drivers/hwtracing/coresight/coresight-platform.c delete mode 100644 drivers/hwtracing/coresight/of_coresight.c ACPI bindings for Juno-r0 (applies on [2] above) Suzuki K Poulose (1): edk2-platform: juno: Update ACPI CoreSight Bindings Platform/ARM/JunoPkg/AcpiTables/Dsdt.asl | 241 +++++++++++++++++++++++++++++++ 1 file changed, 241 insertions(+) -- 2.7.4

7 years

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7 years

OpenCSD v0.11.2

by Wookey

I don't think there was an announcement of v0.11.2, but tools noticed its existence, so I've updated the debian experimental package to match. (New releases are goinging into experimental until Buster is released, probably in the next couple of months) https://tracker.debian.org/pkg/libopencsd https://buildd.debian.org/status/package.php?p=libopencsd&suite=experimental Wookey -- Principal hats: Linaro, Debian, Wookware, ARM http://wookware.org/

7 years

[RFC PATCH v2 0/1] Timestamp perf samples

by Wojciech Żmuda

From: Wojciech Zmuda <wzmuda(a)n7space.com> This patchset adds time notion to perf instruction and branch samples to allow coarse time measurement of code blocks execution. The simplest verification is visibility of the time field in 'perf script' output: root@zynq:~# perf record -e cs_etm/timestamp,(a)fe970000.etr/u -a sleep 1 Couldn't synthesize bpf events. [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.262 MB perf.data ] root@zynq:~# perf script --ns -F cpu,comm,time perf [002] 9546.053455325: perf [002] 9546.053455340: perf [002] 9546.053455344: (...) sleep [003] 9546.060163742: sleep [003] 9546.060163754: sleep [003] 9546.060163766: (...) ntpd [001] 9546.389083194: ntpd [001] 9546.389083400: ntpd [001] 9546.389086319: (...) The step above works only if trace has been collected in CPU-wide mode because of some perf event flags mismatch I'm working on fixing. Timestamps in subsequent samples are monotonically increasing. The only exception are discontinuities in trace. From my understanding, we can't timestamp discontinuities reasonably, since after decoder synchronizes back after trace loss, it needs to wait for another timestamp packet. Thus, time value of such samples stays at 0x0. Another way to access these values is to use the perf script engine, which I used for validation of the feature. The script below calculates timestamp differences of two consecutive branches sharing the same branch address. This is a simple example of execution time fluctuation detector. from __future__ import print_function import os import sys sys.path.append(os.environ['PERF_EXEC_PATH'] + \ '/scripts/python/Perf-Trace-Util/lib/Perf/Trace') from perf_trace_context import * target_start_addr = int('4005e4', 16) # 0x4005e4 is func() from listing below branch = dict() branch['from'] = 0 branches = [] def process_event(s): global branch global branches sample = s['sample'] branch['cpu'] = sample['cpu'] if not branch['from']: branch['from'] = sample['addr'] branch['ts'] = sample['time'] return branch['to'] = sample['ip'] if not branch['to']: branch['from'] = 0 branch['ts'] = 0 return if branch['from'] and branch['to']: branches.append(branch.copy()) branch['from'] = 0 return def trace_end(): global branches count = 0 timestamp_start = 0 print("Got {0} samples:".format(len(branches))) for b in branches: if b['from'] == target_start_addr: if not timestamp_start: timestamp_start = b['ts'] continue print("[{0}]: ts diff = 0x{1:x} - 0x{2:x} = {3:d}".format(count, b['ts'], timestamp_start, b['ts'] - timestamp_start)) count = count + 1 timestamp_start = b['ts'] The following function was traced: static int func(int cnt) { volatile int x = 0; static int i; x += cnt + 0xdeadbeefcafeb00b; (...) /* repeats ~100 times */ if (i++ % 3 == 0) // Every third execution is longer usleep(1000); return x; } root@zynq:~# perf record -m,16K -e cs_etm/timestamp,(a)fe970000.etr/u \ --filter 'filter func @./program \ --per-thread ./program Couldn't synthesize bpf events. CTRL+C me when you find appropriate. ^C[ perf record: Woken up 12 times to write data ] [ perf record: Captured and wrote 0.135 MB perf.data ] root@zynq:~# perf script -s exectime.py Got 2469 samples: [0]: ts diff = 0x92f2752e512 - 0x92f274a7ae9 = 551465 [1]: ts diff = 0x92f2752e694 - 0x92f2752e512 = 386 [2]: ts diff = 0x92f2752e817 - 0x92f2752e694 = 387 [3]: ts diff = 0x92f275bef12 - 0x92f2752e817 = 591611 [4]: ts diff = 0x92f275bf093 - 0x92f275bef12 = 385 [5]: ts diff = 0x92f275bf211 - 0x92f275bf093 = 382 [6]: ts diff = 0x92f276451d7 - 0x92f275bf211 = 548806 [7]: ts diff = 0x92f2764535a - 0x92f276451d7 = 387 [8]: ts diff = 0x92f276454d7 - 0x92f2764535a = 381 [9]: ts diff = 0x92f276cb256 - 0x92f276454d7 = 548223 [10]: ts diff = 0x92f276cb3d9 - 0x92f276cb256 = 387 [11]: ts diff = 0x92f276cb556 - 0x92f276cb3d9 = 381 (...) At the listing above it is visible that every third execution of the function lasted longer than the other two. It is a naive example and could be enhanced to point to the area that caused the disruption by examining events 'in the middle' of the traced code range. Applies cleanly on Mathieu's 5.1-rc3-cpu-wide-v3 branch. Changes for V2: - move packet timestamping logic to decoder. Front end only uses this information to timestamp samples (as suggested by Mathieu). - leave original behaviour of CPU-wide mode, where decoder is stopped and front end is triggered about pending queue with timestamp packet. At the same time, always adjust next and current timestamp in both CPU-wide and per-thread modes (as suggested by Mathieu). - when timestamp packet is encountered, timestamp range and discontinuity packets waiting in the queue, that are not yet consumed by the front end (as suggested by Mathieu). - don't timestamp exceptions, since they are not turned into branch nor instruction samples. - fix timestamping of the last branch sample before discontinuity appears (as suggested by Leo). Wojciech Zmuda (1): perf cs-etm: Set time value for samples tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 70 ++++++++++++++++++++----- tools/perf/util/cs-etm.c | 3 ++ tools/perf/util/cs-etm.h | 1 + 3 files changed, 61 insertions(+), 13 deletions(-) -- 2.11.0

7 years

[RFC PATCH v3] perf test: Introduce script for Arm CoreSight testing

by Leo Yan

We need a simple method to test Perf with Arm CoreSight drivers, this could be used for smoke testing when new patch is coming for perf or CoreSight drivers, and we also can use the test to confirm if the CoreSight has been enabled successfully on new platforms. This patch introduces the shell script test_arm_coresight.sh which is under the 'pert test' framework. Simply to say, the testing rationale is source oriented testing, it traverses every source (now only refers to ETM device) and test its all possible sinks. To search the complete paths from one specific source to its sinks, this patch relies on the sysfs '/sys/bus/coresight/devices/devX/out:Y' for depth-first search (DFS) for iteration connected device nodes, if the output device is detected as one of ETR, ETF, or ETB types then it will test trace data recording and decoding for this PMU device. The script runs three output testings for every trace data: - Test branch samples dumping with 'perf script' command; - Test branch samples reporting with 'perf report' command; - Use option '--itrace=i1000i' to insert synthesized instructions events and the script will check if perf can output the percentage value successfully based on the instruction samples. If any device fails for the testing, the test will report failure and directly exit with error. This test will be only applied on the platform with PMU event 'cs_etm//', otherwise will skip the testing. Below is detailed usage for it: # cd $linux/tools/perf -> This is important so can use shell script # perf test list [...] 61: Check Arm CoreSight trace data recording and branch samples 62: Check open filename arg using perf trace + vfs_getname 63: Zstd perf.data compression/decompression 64: Add vfs_getname probe to get syscall args filenames # perf test 61 61: Check Arm CoreSight trace data recording and branch samples: Ok Signed-off-by: Leo Yan <leo.yan(a)linaro.org> --- tools/perf/tests/shell/test_arm_coresight.sh | 120 +++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100755 tools/perf/tests/shell/test_arm_coresight.sh diff --git a/tools/perf/tests/shell/test_arm_coresight.sh b/tools/perf/tests/shell/test_arm_coresight.sh new file mode 100755 index 000000000000..7b1fa17a4512 --- /dev/null +++ b/tools/perf/tests/shell/test_arm_coresight.sh @@ -0,0 +1,120 @@ +#!/bin/sh +# Check Arm CoreSight trace data recording and branch samples + +# Uses the 'perf record' to record trace data with Arm CoreSight sinks; +# then verify if there have any branch samples and instruction samples +# are generated by CoreSight with 'perf script' and 'perf report' +# commands. + +# Leo Yan <leo.yan(a)linaro.org>, 2019 + +perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX) +file=$(mktemp /tmp/temporary_file.XXXXX) + +skip_if_no_cs_etm_event() { + perf list | grep -q 'cs_etm//' && return 0 + + # cs_etm event doesn't exist + return 2 +} + +skip_if_no_cs_etm_event || exit 2 + +record_touch_file() { + echo "Recording trace (only user mode) with path: CPU$2 => $1" + perf record -o ${perfdata} -e cs_etm/@$1/u --per-thread \ + -- taskset -c $2 touch $file +} + +perf_script_branch_samples() { + echo "Looking at perf.data file for dumping branch samples:" + + # Below is an example of the branch samples dumping: + # touch 6512 1 branches:u: ffffb220824c strcmp+0xc (/lib/aarch64-linux-gnu/ld-2.27.so) + # touch 6512 1 branches:u: ffffb22082e0 strcmp+0xa0 (/lib/aarch64-linux-gnu/ld-2.27.so) + # touch 6512 1 branches:u: ffffb2208320 strcmp+0xe0 (/lib/aarch64-linux-gnu/ld-2.27.so) + perf script -F,-time -i ${perfdata} | \ + egrep " +touch +[0-9]+ .* +branches:([u|k]:)? +" +} + +perf_report_branch_samples() { + echo "Looking at perf.data file for reporting branch samples:" + + # Below is an example of the branch samples reporting: + # 73.04% 73.04% touch libc-2.27.so [.] _dl_addr + # 7.71% 7.71% touch libc-2.27.so [.] getenv + # 2.59% 2.59% touch ld-2.27.so [.] strcmp + perf report --stdio -i ${perfdata} | \ + egrep " +[0-9]+\.[0-9]+% +[0-9]+\.[0-9]+% +touch " +} + +perf_report_instruction_samples() { + echo "Looking at perf.data file for instruction samples:" + + # Below is an example of the instruction samples reporting: + # 68.12% touch libc-2.27.so [.] _dl_addr + # 5.80% touch libc-2.27.so [.] getenv + # 4.35% touch ld-2.27.so [.] _dl_fixup + perf report --itrace=i1000i --stdio -i ${perfdata} | \ + egrep " +[0-9]+\.[0-9]+% +touch" +} + +arm_cs_iterate_devices() { + for dev in $1/out\:*; do + + # Skip testing if it's not a directory + ! [ -d $dev ] && continue; + + # Read out its symbol link file name + path=`readlink -f $dev` + + # Extract device name from path, e.g. + # path = '/sys/devices/platform/20010000.etf/tmc_etf0' + # `> device_name = 'tmc_etf0' + device_name=`echo $path | awk -F/ '{print $(NF)}'` + + echo $device_name | egrep -q "etr|etb|etf" + + # Only test if the output device is ETR/ETB/ETF + if [ $? -eq 0 ]; then + + pmu_dev="/sys/bus/event_source/devices/cs_etm/sinks/$device_name" + + # Exit if PMU device node doesn't exist + if ! [ -f $pmu_dev ]; then + echo "PMU device $pmu_dev doesn't exist" + exit 1 + fi + + record_touch_file $device_name $2 && + perf_script_branch_samples && + perf_report_branch_samples && + perf_report_instruction_samples + + err=$? + + # Exit when find failure + [ $err != 0 ] && exit $err + + rm -f ${perfdata} + rm -f ${file} + fi + + arm_cs_iterate_devices $dev $2 + done +} + +arm_cs_etm_test() { + # Iterate for every ETM device + for dev in /sys/bus/coresight/devices/etm*; do + + # Find the ETM device belonging to which CPU + cpu=`cat $dev/cpu` + + # Use depth-first search (DFS) to iterate outputs + arm_cs_iterate_devices $dev $cpu + done +} + +arm_cs_etm_test +exit 0 -- 2.17.1

7 years

[PATCH 0/3] coresight: Expose device connections via sysfs

by Suzuki K Poulose

Coresight device connections are a bit complicated and is not exposed currently to the user. One has to look at the platform descriptions (DT bindings or ACPI bindings) to make an understanding. Given the new naming scheme, it will be helpful to have this information to choose the appropriate devices for tracing. This patch exposes the device connections via links in the sysfs directories. e.g, for a connection devA[OutputPort_X] -> devB[InputPort_Y] is represented as two symlinks: /sys/bus/coresight/.../devA/out:X -> /sys/bus/coresight/.../devB /sys/bus/coresight/.../devB/in:Y -> /sys/bus/coresight/.../devA Applies on coresight/next tree. This is split from the ACPI bindings series. No functional changes. Suzuki K Poulose (3): coresight: Pass coresight_device for coresight_release_platform_data coresight: add return value for fixup connections coresight: Expose device connections via sysfs drivers/hwtracing/coresight/coresight-platform.c | 2 +- drivers/hwtracing/coresight/coresight-priv.h | 3 +- drivers/hwtracing/coresight/coresight.c | 148 +++++++++++++++++++---- include/linux/coresight.h | 4 + 4 files changed, 132 insertions(+), 25 deletions(-) -- 2.7.4

7 years

[PATCH 0/4] coresight: Do not call smp_processor_id from preemptible contexts

by Suzuki K Poulose

We have a few places where we call smp_processor_id() from preemptible contexts during the perf buffer handling. We do this to figure out the numa node for the allocation in case the event is not CPU bound. Use numa_node_id() instead in such cases to avoid a splat. Suzuki K Poulose (4): coresight: tmc-etr: Do not call smp_processor_id() from preemptible coresight: tmc-etr: alloc_perf_buf: Do not call smp_processor_id from preemptible coresight: tmc-etf: Do not call smp_processor_id from preemptible coresight: etb10: Do not call smp_processor_id from preemptible drivers/hwtracing/coresight/coresight-etb10.c | 6 ++---- drivers/hwtracing/coresight/coresight-tmc-etf.c | 6 ++---- drivers/hwtracing/coresight/coresight-tmc-etr.c | 13 ++++--------- 3 files changed, 8 insertions(+), 17 deletions(-) -- 2.7.4

7 years

[RFC PATCH 0/1] Timestamp perf samples

by Wojciech Żmuda

From: Wojciech Zmuda <wzmuda(a)n7space.com> Hello, After our discussion in [1] I came up with this proposal solution on how to timestamp perf samples, so we can tell in trace post-processing, how long does it take to execute traced blocks of code. I'll be grateful if you find some time to take a look at it. The patch itself is 37 lines of additions, so it shouldn't consume a lot of your time. I also have some ideas to further improve this patch I'm not quite sure about, so I'd like to ask you for your input. The simplest verification is visibility of the time field in 'perf script' output: root@zynq:~# perf script --ns -F comm,cpu,event,time | head Frame deformatter: Found 4 FSYNCS singlethread-at [001] 4572.697372400: branches:u: singlethread-at [001] 4572.697372404: branches:u: singlethread-at [001] 4572.697372408: branches:u: singlethread-at [001] 4572.697372412: branches:u: singlethread-at [001] 4572.697372416: branches:u: The step above works only if trace has been collected in CPU-wide mode. I have an idea on how to improve this, but I'd like to get some more information first. I elaborated in the last paragraph. Another way to access these values is using the script engine, which I used for validation of sanity of timestamp values. Using python script I checked if timestamps in subsequent samples are monotonically increasing and it seems they are. The only exception are discontinuities in trace. From my understanding, we can't timestamp discontinuities reasonably, since after decoder synchronizes back after trace loss, it needs to wait for another timestamp packet. from __future__ import print_function import os import sys sys.path.append(os.environ['PERF_EXEC_PATH'] + \ '/scripts/python/Perf-Trace-Util/lib/Perf/Trace') from perf_trace_context import * prev_sample = 0 cnt = 0; def process_event(s): global prev_sample global cnt sample = s['sample'] if not prev_sample: prev_sample = sample; cnt = cnt+1 return if sample['time'] < prev_sample['time']: print('Sample %d has higher timestamp than sample %d' % (cnt-1, cnt)) cnt = cnt+1 By subtracting timestamps of two samples, we can approximately tell, how long did it take (in timestamp units) to execute instructions between these two points. Now, (basing on Al's response in [1]) knowing the timestamp generator clock frequency, we can tell how long did it take in proper time units. The frequency is known (we have it in DT) and can be saved to and retrieved from TSGEN register. This is not done at this moment (the register is empty), but the idea is, if it was, it might then be saved in perf.data headers (similarly as TRCIDR are saved now), and later programmatically retrieved to calculate timestamp differences into actual time. I didn't experiment with it yet - I'd like to learn your opinion on it. I've also tried to access the time field with 'perf script -F time' and while it's possible for traces recorded in CPU-wide mode, it's not possible in per-thread mode due to PERF_SAMPLE_TIME not being set in that mode (cs_etm__synth_events()). I tried to analyze that code, but I can't understand relation between this flag and ETM's timeless_decoding property. It looks to me that timeless decoding was equal to per-thread mode, where timestamps were not really utilized, while in CPU-wide mode they were used to inter-queue correlation. Would it be a good direction to have a separate property of TSGEN being on/off and to set PERF_SAMPLE_TIME based on this, rather than on etm->timeless_decoding? I see an obstacle in the cs_etm__is_timeless_decoding() function, that sets etm->timeless_decoding basing on events having this SAMPLE_TIME flag or not - could the criterion here be the tracing mode (CPU-wide/per-thread) instead? Thank you, Wojciech [1] https://lists.linaro.org/pipermail/coresight/2019-May/002577.html Wojciech Zmuda (1): perf cs-etm: Set time value for samples tools/perf/util/cs-etm.c | 36 ++++++++++++++++++++++++++++++++++++ tools/perf/util/cs-etm.h | 1 + 2 files changed, 37 insertions(+) -- 2.11.0

7 years

[PATCH V2 0/6] coresight: Fix snapshot mode

by Mathieu Poirier

This is the second revision of a set that fix miscellaneous problems preventing snapshot mode from working properly when CoreSight events are used. It applies cleanly on the coresight next branch[1] and will be posted again when 5.2-rc1 comes out. Best regards, Mathieu [1]. https://git.linaro.org/kernel/coresight.git/ branch next Changes for V2: * Drop requirement to make the perf AUX buffer the same size as the sink buffers. * Re-worked the user space algorithm to find '*head' and '*old". * Fixed typo in changelogs (Leo). Mathieu Poirier (6): coresight: etb10: Properly set AUX buffer head in snapshot mode coresight: tmc-etr: Properly set AUX buffer head in snapshot mode coresight: tmc-etf: Properly set AUX buffer head in snapshot mode coresight: tmc-etf: Fix snapshot mode update function coresight: perf: Don't set the truncated flag in snapshot mode perf tools: Properly set the value of 'old' and 'head' in snapshot mode drivers/hwtracing/coresight/coresight-etb10.c | 21 ++- .../hwtracing/coresight/coresight-tmc-etf.c | 28 ++-- .../hwtracing/coresight/coresight-tmc-etr.c | 19 ++- tools/perf/arch/arm/util/cs-etm.c | 124 +++++++++++++++++- 4 files changed, 165 insertions(+), 27 deletions(-) -- 2.17.1

7 years

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