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Date: Sun, 27 Jun 2021 19:50:13 +0800
From: Leo Yan <leo.yan@...aro.org>
To: James Clark <james.clark@....com>
Cc: acme@...nel.org, mathieu.poirier@...aro.org,
coresight@...ts.linaro.org, al.grant@....com,
branislav.rankov@....com, denik@...omium.org,
suzuki.poulose@....com, anshuman.khandual@....com,
John Garry <john.garry@...wei.com>,
Will Deacon <will@...nel.org>,
Mike Leach <mike.leach@...aro.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/2] perf cs-etm: Split Coresight decode by aux records
On Thu, Jun 24, 2021 at 05:43:02PM +0100, James Clark wrote:
> Populate the auxtrace queues using AUX records rather than whole
> auxtrace buffers so that the decoder is reset between each aux record.
[...]
> Signed-off-by: James Clark <james.clark@....com>
I tested this patch with kprobe/uprobe events; and confirmed this
patch works as expected. So:
Tested-by: Leo Yan <leo.yan@...aro.org>
Below shares my testing steps.
- The rationale for the testing is to use "perf probe" to add trace
points for PERF_RECORD_AUX/PERF_RECORD_AUXTRACE, and add another
uprobe event for parsing AUX fragment. So we can compare the
recorded PERF_RECORD_AUX events, and check if AUX fragment can
reorganize the perf AUX trace data correctly or not.
- The testing script test_cs_etm_snapshot.sh:
http://paste.debian.net/1202563/
- Add kprobe event for perf_event_aux_event() so that it can trace
the perf event PERF_RECORD_AUX:
# perf probe --add "perf_event_aux_event head=head:x64 size=size:x64"
- Add uprobe event for __auxtrace_mmap__read() so that it can trace
the perf event PERF_RECORD_AUXTRACE:
# perf probe -x /mnt/linux-kernel/linux-cs-dev/tools/perf/perf \
--add "__auxtrace_mmap__read:58 idx=mm->idx head=head:x64 offset=offset:x64 size=size:x64"
- Add uprobe event for cs_etm__queue_aux_fragment():
# perf probe -x /mnt/linux-kernel/linux-cs-dev/tools/perf/perf \
--add "cs_etm__queue_aux_fragment:63 aux_offset=aux_offset:x64 aux_size=aux_event->aux_size:x64"
- Enable trace events:
# cd /sys/kernel/debug/tracing
# echo 1 > events/probe/enable
# echo 1 > events/probe_perf/enable
- Executed the testing script and perf report command:
# sh test_cs_etm_snapshot.sh
[ perf record: Woken up 7 times to write data ]
[ perf record: Captured and wrote 19.534 MB /tmp/__perf_test.perf.data.miRDs ]
# perf report -i /tmp/__perf_test.perf.data.miRDs
- At the end, I can get the tracing result:
# cd /sys/kernel/debug/tracing
# cat trace
# entries-in-buffer/entries-written: 21/21 #P:6
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
dd-2206 [001] d.h3 1395.922396: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0x400000 size=0x400000
perf-2204 [002] .... 1395.922565: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0x400000 offset=0x0 size=0x400000
dd-2206 [001] d.h3 1395.942658: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0x50b3f0 size=0x10b3f0
perf-2204 [002] .... 1395.942739: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0x50b3f0 offset=0x400000 size=0x10b3f0
dd-2206 [001] d.h3 1396.000040: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0x90b3f0 size=0x400000
perf-2204 [002] .... 1396.000150: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0x90b3f0 offset=0x50b3f0 size=0x400000
dd-2206 [001] d.h3 1396.023098: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0xb87ae0 size=0x27c6f0
perf-2204 [002] .... 1396.023197: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0xb87ae0 offset=0x90b3f0 size=0x27c6f0
dd-2206 [001] d.h3 1396.087722: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0xf87ae0 size=0x400000
perf-2204 [002] .... 1396.087838: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0xf87ae0 offset=0xb87ae0 size=0x400000
dd-2206 [001] d.h3 1396.131696: perf_event_aux_event: (perf_event_aux_event+0x0/0x108) head=0x1387ae0 size=0x400000
perf-2204 [002] .... 1396.131808: __auxtrace_mmap__read_L58: (0xaaaaab154394) idx=1 head=0x1387ae0 offset=0xf87ae0 size=0x400000
perf-2217 [003] .... 1439.581363: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0x0 aux_size=0x400000
perf-2217 [003] .... 1439.581467: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0x400000 aux_size=0x10b3f0
perf-2217 [003] .... 1439.581510: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0x50b3f0 aux_size=0x400000
perf-2217 [003] .... 1439.581553: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0x90b3f0 aux_size=0x27c6f0
perf-2217 [003] .... 1439.581595: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0xb87ae0 aux_size=0x400000
perf-2217 [003] .... 1439.581638: cs_etm__queue_aux_fragment_L63: (0xaaaac9582ba8) aux_offset=0xf87ae0 aux_size=0x400000
We can see the recording AUX trace data in perf_event_aux_event()
can be decoded properly in events cs_etm__queue_aux_fragment_L63().
Thanks,
Leo
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