mirror of https://github.com/torvalds/linux.git
7 Commits
| Author | SHA1 | Message | Date |
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Song Liu
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5508c9dae2 |
perf stat: Introduce bpf_counter_ops->disable()
Introduce bpf_counter_ops->disable(), which is used stop counting the event. Committer notes: Added a dummy bpf_counter__disable() to the python binding to avoid having 'perf test python' failing. bpf_counter isn't supported in the python binding. Signed-off-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: kernel-team@fb.com Link: https://lore.kernel.org/r/20210425214333.1090950-6-song@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Song Liu
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01bd8efcec |
perf stat: Introduce ':b' modifier
Introduce 'b' modifier to event parser, which means use BPF program to manage this event. This is the same as --bpf-counters option, but only applies to this event. For example, perf stat -e cycles:b,cs # use bpf for cycles, but not cs perf stat -e cycles,cs --bpf-counters # use bpf for both cycles and cs Suggested-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Song Liu <song@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/r/20210425214333.1090950-5-song@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Song Liu
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112cb56164 |
perf stat: Introduce config stat.bpf-counter-events
Currently, to use BPF to aggregate perf event counters, the user uses --bpf-counters option. Enable "use bpf by default" events with a config option, stat.bpf-counter-events. Events with name in the option will use BPF. This also enables mixed BPF event and regular event in the same sesssion. For example: perf config stat.bpf-counter-events=instructions perf stat -e instructions,cs The second command will use BPF for "instructions" but not "cs". Signed-off-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/r/20210425214333.1090950-4-song@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Song Liu
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fe3dd8263b |
perf bpf: check perf_attr_map is compatible with the perf binary
perf_attr_map could be shared among different version of perf binary. Add bperf_attr_map_compatible() to check whether the existing attr_map is compatible with current perf binary. Signed-off-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: kernel-team@fb.com Link: https://lore.kernel.org/r/20210425214333.1090950-3-song@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Song Liu
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ec8149fba6 |
perf util: Move bpf_perf definitions to a libperf header
By following the same protocol, other tools can share hardware PMCs with perf. Move perf_event_attr_map_entry and BPF_PERF_DEFAULT_ATTR_MAP_PATH to bpf_perf.h for other tools to use. Signed-off-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: kernel-team@fb.com Link: https://lore.kernel.org/r/20210425214333.1090950-2-song@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Song Liu
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7fac83aaf2 |
perf stat: Introduce 'bperf' to share hardware PMCs with BPF
The perf tool uses performance monitoring counters (PMCs) to monitor
system performance. The PMCs are limited hardware resources. For
example, Intel CPUs have 3x fixed PMCs and 4x programmable PMCs per cpu.
Modern data center systems use these PMCs in many different ways: system
level monitoring, (maybe nested) container level monitoring, per process
monitoring, profiling (in sample mode), etc. In some cases, there are
more active perf_events than available hardware PMCs. To allow all
perf_events to have a chance to run, it is necessary to do expensive
time multiplexing of events.
On the other hand, many monitoring tools count the common metrics
(cycles, instructions). It is a waste to have multiple tools create
multiple perf_events of "cycles" and occupy multiple PMCs.
bperf tries to reduce such wastes by allowing multiple perf_events of
"cycles" or "instructions" (at different scopes) to share PMUs. Instead
of having each perf-stat session to read its own perf_events, bperf uses
BPF programs to read the perf_events and aggregate readings to BPF maps.
Then, the perf-stat session(s) reads the values from these BPF maps.
Please refer to the comment before the definition of bperf_ops for the
description of bperf architecture.
bperf is off by default. To enable it, pass --bpf-counters option to
perf-stat. bperf uses a BPF hashmap to share information about BPF
programs and maps used by bperf. This map is pinned to bpffs. The
default path is /sys/fs/bpf/perf_attr_map. The user could change the
path with option --bpf-attr-map.
Committer testing:
# dmesg|grep "Performance Events" -A5
[ 0.225277] Performance Events: Fam17h+ core perfctr, AMD PMU driver.
[ 0.225280] ... version: 0
[ 0.225280] ... bit width: 48
[ 0.225281] ... generic registers: 6
[ 0.225281] ... value mask: 0000ffffffffffff
[ 0.225281] ... max period: 00007fffffffffff
#
# for a in $(seq 6) ; do perf stat -a -e cycles,instructions sleep 100000 & done
[1] 2436231
[2] 2436232
[3] 2436233
[4] 2436234
[5] 2436235
[6] 2436236
# perf stat -a -e cycles,instructions sleep 0.1
Performance counter stats for 'system wide':
310,326,987 cycles (41.87%)
236,143,290 instructions # 0.76 insn per cycle (41.87%)
0.100800885 seconds time elapsed
#
We can see that the counters were enabled for this workload 41.87% of
the time.
Now with --bpf-counters:
# for a in $(seq 32) ; do perf stat --bpf-counters -a -e cycles,instructions sleep 100000 & done
[1] 2436514
[2] 2436515
[3] 2436516
[4] 2436517
[5] 2436518
[6] 2436519
[7] 2436520
[8] 2436521
[9] 2436522
[10] 2436523
[11] 2436524
[12] 2436525
[13] 2436526
[14] 2436527
[15] 2436528
[16] 2436529
[17] 2436530
[18] 2436531
[19] 2436532
[20] 2436533
[21] 2436534
[22] 2436535
[23] 2436536
[24] 2436537
[25] 2436538
[26]
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Song Liu
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fa853c4b83 |
perf stat: Enable counting events for BPF programs
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>
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