5.15 kernel needs at least backporting the following patch to make the perf
working as expected:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/perf/arm_pmu.c?id=5c816728651ae425954542fed64d21d40cb75a9f
$ sudo taskset -c 7 ./perf stat -e armv8_cortex_a55/cpu_cycles/ -e
armv8_cortex_a78/cpu_
cycles/ -e cycles sleep 5
Performance counter stats for 'sleep 5':
<not counted> armv8_cortex_a55/cpu_cycles/
(0.00%)
1451459 armv8_cortex_a78/cpu_cycles/
<not counted> cycles
(0.00%)
5.001872700 seconds time elapsed
0.001533000 seconds user
0.000000000 seconds sys
$ sudo taskset -c 0 ./perf stat -e armv8_cortex_a55/cpu_cycles/ -e
armv8_cortex_a78/cpu_
cycles/ -e cycles sleep 5
Performance counter stats for 'sleep 5':
3089794 armv8_cortex_a55/cpu_cycles/
<not counted> armv8_cortex_a78/cpu_cycles/
(0.00%)
3089794 cycles
5.005167986 seconds time elapsed
0.000000000 seconds user
0.004539000 seconds sys
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https://bugs.launchpad.net/bugs/2060063
Title:
PMU counters for Cortex-A78 not working correctly
Status in linux-mtk package in Ubuntu:
Invalid
Status in linux-mtk source package in Jammy:
In Progress
Bug description:
I am seeing an issue with the Cortex-A78 PMU counters on the
Genio1200-evk.
Linux perf reports <not counted> for Cortex-A78 PMUs when I run the following
commands:
taskset -c 7 perf stat -e cycles sleep 5
taskset -c 7 perf stat -r r11 sleep 5
Infact none of the standard PMU events on the Cortex-A78 work when
using the raw PMU event register values such as:
-e r08
-e r11
-e r13
:
...... etc.
I also see this behaviour when an application using libpfm4 OR
perf_event_open() API is pinned to one of the 4xCortex-A78 on the
board.
When I run the above perf commands and applications pinned to the
Cortex-A55 cores the PMU events get reported correctly.
Please let me know if you need more details.
Kind regards,
Umair
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