The current logic for the perf missing feature has a bug that it can
wrongly clear some modifiers like G or H. Actually some PMUs don't
support any filtering or exclusion while others do. But we check it as
a global feature.
For example, the cycles event can have 'G' modifier to enable it only in
the guest mode on x86. When you don't run any VMs it'll return 0.
# perf stat -a -e cycles:G sleep 1
Performance counter stats for 'system wide':
0 cycles:G
1.000721670 seconds time elapsed
But when it's used with other pmu events that don't support G modifier,
it'll be reset and return non-zero values.
# perf stat -a -e cycles:G,msr/tsc/ sleep 1
Performance counter stats for 'system wide':
538,029,960 cycles:G
16,924,010,738 msr/tsc/
1.001815327 seconds time elapsed
This is because of the missing feature detection logic being global.
Add a hashmap to set pmu-specific exclude_host/guest features.
Committer notes:
Fix 'perf test python' by adding a stub for evsel__find_pmu() in
tools/perf/util/python.c, document that it is used so far only for the
above reasons so that if anybody needs this in the python binding
usecases, we can revisit this.
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Link: http://lore.kernel.org/lkml/20211105205847.120950-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Introduce 'perf stat -b' option, which counts events for BPF programs, like:
[root@localhost ~]# ~/perf stat -e ref-cycles,cycles -b 254 -I 1000
1.487903822 115,200 ref-cycles
1.487903822 86,012 cycles
2.489147029 80,560 ref-cycles
2.489147029 73,784 cycles
3.490341825 60,720 ref-cycles
3.490341825 37,797 cycles
4.491540887 37,120 ref-cycles
4.491540887 31,963 cycles
The example above counts 'cycles' and 'ref-cycles' of BPF program of id
254. This is similar to bpftool-prog-profile command, but more
flexible.
'perf stat -b' creates per-cpu perf_event and loads fentry/fexit BPF
programs (monitor-progs) to the target BPF program (target-prog). The
monitor-progs read perf_event before and after the target-prog, and
aggregate the difference in a BPF map. Then the user space reads data
from these maps.
A new 'struct bpf_counter' is introduced to provide a common interface
that uses BPF programs/maps to count perf events.
Committer notes:
Removed all but bpf_counter.h includes from evsel.h, not needed at all.
Also BPF map lookups for PERCPU_ARRAYs need to have as its value receive
buffer passed to the kernel libbpf_num_possible_cpus() entries, not
evsel__nr_cpus(evsel), as the former uses
/sys/devices/system/cpu/possible while the later uses
/sys/devices/system/cpu/online, which may be less than the 'possible'
number making the bpf map lookup overwrite memory and cause hard to
debug memory corruption.
We need to continue using evsel__nr_cpus(evsel) when accessing the
perf_counts array tho, not to overwrite another are of memory :-)
Signed-off-by: Song Liu <songliubraving@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/lkml/20210120163031.GU12699@kernel.org/
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20201229214214.3413833-4-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Perf record with verbose=2 already prints this information along with
whole lot of other traces which requires lot of scrolling. Introduce
an option to print only perf_event_open() arguments and return value.
Sample o/p:
$ perf --debug perf-event-open=1 record -- ls > /dev/null
------------------------------------------------------------
perf_event_attr:
size 112
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|PERIOD
read_format ID
disabled 1
inherit 1
exclude_kernel 1
mmap 1
comm 1
freq 1
enable_on_exec 1
task 1
precise_ip 3
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
ksymbol 1
bpf_event 1
------------------------------------------------------------
sys_perf_event_open: pid 4308 cpu 0 group_fd -1 flags 0x8 = 4
sys_perf_event_open: pid 4308 cpu 1 group_fd -1 flags 0x8 = 5
sys_perf_event_open: pid 4308 cpu 2 group_fd -1 flags 0x8 = 6
sys_perf_event_open: pid 4308 cpu 3 group_fd -1 flags 0x8 = 8
sys_perf_event_open: pid 4308 cpu 4 group_fd -1 flags 0x8 = 9
sys_perf_event_open: pid 4308 cpu 5 group_fd -1 flags 0x8 = 10
sys_perf_event_open: pid 4308 cpu 6 group_fd -1 flags 0x8 = 11
sys_perf_event_open: pid 4308 cpu 7 group_fd -1 flags 0x8 = 12
------------------------------------------------------------
perf_event_attr:
type 1
size 112
config 0x9
watermark 1
sample_id_all 1
bpf_event 1
{ wakeup_events, wakeup_watermark } 1
------------------------------------------------------------
sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8
sys_perf_event_open failed, error -13
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.002 MB perf.data (9 samples) ]
Committer notes:
Just like the 'verbose' variable this new 'debug_peo_args' needs to be
added to util/python.c, since we don't link the debug.o file in the
python binding, which ended up making 'perf test python' fail with:
# perf test -v python
18: 'import perf' in python :
--- start ---
test child forked, pid 19237
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.so: undefined symbol: debug_peo_args
test child finished with -1
---- end ----
'import perf' in python: FAILED!
#
After adding that new variable to util/python.c:
# perf test -v python
18: 'import perf' in python :
--- start ---
test child forked, pid 22364
test child finished with 0
---- end ----
'import perf' in python: Ok
#
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191108094128.28769-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
