When running topdown leader smapling test on Intel hybrid platforms,
such as LNL/ARL, we see the below error.
Topdown leader sampling test
Topdown leader sampling [Failed topdown events not reordered correctly]
It indciates the below command fails.
perf record -o "${perfdata}" -e "{instructions,slots,topdown-retiring}:S" true
The root cause is that perf tool creats a perf event for each PMU type
if it can create.
As for this command, there would be 5 perf events created,
cpu_atom/instructions/,cpu_atom/topdown_retiring/,
cpu_core/slots/,cpu_core/instructions/,cpu_core/topdown-retiring/
For these 5 events, the 2 cpu_atom events are in a group and the other 3
cpu_core events are in another group.
When arch_topdown_sample_read() traverses all these 5 events, events
cpu_atom/instructions/ and cpu_core/slots/ don't have a same group
leade, and then return false directly and lead to cpu_core/slots/ event
is used to sample and this is not allowed by PMU driver.
It's a overkill to return false directly if "evsel->core.leader !=
leader->core.leader" since there could be multiple groups in the event
list.
Just "continue" instead of "return false" to fix this issue.
Fixes: 1e53e9d178 ("perf x86/topdown: Correct leader selection with sample_read enabled")
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Thomas Falcon <thomas.falcon@intel.com>
Tested-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250307023906.1135613-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Leverage the existed function perf_pmu__name_from_config() to check if
an event is topdown metrics event. perf_pmu__name_from_config() goes
through the defined formats and figures out the config of pre-defined
topdown events.
This avoids to figure out the config of topdown pre-defined events with
hard-coded format strings "event=" and "umask=" and provides more
flexibility.
Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20241011110207.1032235-2-dapeng1.mi@linux.intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Addresses an issue where, in the absence of a topdown metrics event
within a sampling group, the slots event was incorrectly bypassed as
the sampling leader when sample_read was enabled.
perf record -e '{slots,branches}:S' -c 10000 -vv sleep 1
In this case, the slots event should be sampled as leader but the
branches event is sampled in fact like the verbose output shows.
perf_event_attr:
type 4 (cpu)
size 168
config 0x400 (slots)
sample_type IP|TID|TIME|READ|CPU|IDENTIFIER
read_format ID|GROUP|LOST
disabled 1
sample_id_all 1
exclude_guest 1
------------------------------------------------------------
sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 5
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
size 168
config 0x4 (PERF_COUNT_HW_BRANCH_INSTRUCTIONS)
{ sample_period, sample_freq } 10000
sample_type IP|TID|TIME|READ|CPU|IDENTIFIER
read_format ID|GROUP|LOST
sample_id_all 1
exclude_guest 1
The sample period of slots event instead of branches event is reset to
0.
This fix ensures the slots event remains the leader under these
conditions.
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20240913084712.13861-3-dapeng1.mi@linux.intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
It's not complete to check whether an event is a topdown slots or
topdown metrics event by only comparing the event name since user
may assign the event by RAW format, e.g.
perf stat -e '{instructions,cpu/r400/,cpu/r8300/}' sleep 1
Performance counter stats for 'sleep 1':
<not counted> instructions
<not counted> cpu/r400/
<not supported> cpu/r8300/
1.002917796 seconds time elapsed
0.002955000 seconds user
0.000000000 seconds sys
The RAW format slots and topdown-be-bound events are not recognized and
not regroup the events, and eventually cause error.
Thus add two helpers arch_is_topdown_slots()/arch_is_topdown_metrics()
to detect whether an event is topdown slots/metrics event by comparing
the event config directly, and use these two helpers to replace the
original event name comparisons.
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20240913084712.13861-2-dapeng1.mi@linux.intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
With the hardware TopDown metrics feature, the sample-read feature should
be supported for a TopDown group, e.g., sample a non-topdown event and read
a Topdown metric group. But the current perf record code errors are out.
For a TopDown metric group,the slots event must be the leader of the group,
but the leader slots event doesn't support sampling. To support sample-read
the TopDown metric group, uses the 2nd event of the group as the "leader"
for the purposes of sampling.
Only the platform with the TopDown metric feature supports sample-read the
topdown group. In commit acb65150a4 ("perf record: Support sample-read
topdown metric group"), it adds arch_topdown_sample_read() to indicate
whether the TopDown group supports sample-read, it should only work on the
non-hybrid systems, this patch extends the support for hybrid platforms.
Before:
# ./perf record -e "{cpu_core/slots/,cpu_core/cycles/,cpu_core/topdown-retiring/}:S" -a sleep 1
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu_core/topdown-retiring/).
/bin/dmesg | grep -i perf may provide additional information.
After:
# ./perf record -e "{cpu_core/slots/,cpu_core/cycles/,cpu_core/topdown-retiring/}:S" -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.238 MB perf.data (369 samples) ]
Fixes: acb65150a4 ("perf record: Support sample-read topdown metric group")
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220602153603.1884710-1-zhengjun.xing@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The commit 94dbfd6781 ("perf parse-events: Architecture specific
leader override") introduced a feature to reorder the slots event to
fulfill the restriction of the perf metrics topdown group. But the
feature doesn't work on the hybrid machine.
$ perf stat -e "{cpu_core/instructions/,cpu_core/slots/,cpu_core/topdown-retiring/}" -a sleep 1
Performance counter stats for 'system wide':
<not counted> cpu_core/instructions/
<not counted> cpu_core/slots/
<not supported> cpu_core/topdown-retiring/
1.002871801 seconds time elapsed
A hybrid platform has a different PMU name for the core PMUs, while
current perf hard code the PMU name "cpu".
Introduce a new function to check whether the system supports the perf
metrics feature. The result is cached for the future usage.
For X86, the core PMU name always has "cpu" prefix.
With the patch:
$ perf stat -e "{cpu_core/instructions/,cpu_core/slots/,cpu_core/topdown-retiring/}" -a sleep 1
Performance counter stats for 'system wide':
76,337,010 cpu_core/slots/
10,416,809 cpu_core/instructions/
11,692,372 cpu_core/topdown-retiring/
1.002805453 seconds time elapsed
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220518143900.1493980-5-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
With the hardware TopDown metrics feature, sample-read feature should be
supported for a topdown group, e.g., sample a non-topdown event and read
a topdown metric group. But the current perf record code errors out.
For a topdown metric group, the slots event must be the leader of the
group, but the leader slots event doesn't support sampling.
To support sample-read the topdown metric group, use the 2nd event of
the group as the "leader" for the purposes of sampling.
Only the platform with Topdown metic feature supports sample-read the
topdown group. Add arch_topdown_sample_read() to indicate whether the
topdown group supports sample-read.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200911144808.27603-3-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
