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bpftool: profile online CPUs instead of possible

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The number of online cpu may be not equal to possible cpu.
"bpftool prog profile" can not create pmu event on possible
but on online cpu.

$ dmidecode -s system-product-name
PowerEdge R620
$ cat /sys/devices/system/cpu/possible
0-47
$ cat /sys/devices/system/cpu/online
0-31

Disable cpu dynamically:
$ echo 0 > /sys/devices/system/cpu/cpuX/online

If one cpu is offline, perf_event_open will return ENODEV.
To fix this issue:
* check value returned and skip offline cpu.
* close pmu_fd immediately on error path, avoid fd leaking.

Fixes: 47c09d6a9f ("bpftool: Introduce "prog profile" command")
Signed-off-by: Tonghao Zhang <tong@infragraf.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20230202131701.29519-1-tong@infragraf.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Tonghao Zhang 2023-02-02 21:17:01 +08:00 committed by Martin KaFai Lau
parent 0a312cf8db
commit 377c16fa3f
1 changed files with 30 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
tools/bpf/bpftool/prog.c
View file

@ -2233,10 +2233,38 @@ static void profile_close_perf_events(struct profiler_bpf *obj)
profile_perf_event_cnt = 0;
}
static int profile_open_perf_event(int mid, int cpu, int map_fd)
{
int pmu_fd;
pmu_fd = syscall(__NR_perf_event_open, &metrics[mid].attr,
-1 /*pid*/, cpu, -1 /*group_fd*/, 0);
if (pmu_fd < 0) {
if (errno == ENODEV) {
p_info("cpu %d may be offline, skip %s profiling.",
cpu, metrics[mid].name);
profile_perf_event_cnt++;
return 0;
}
return -1;
}
if (bpf_map_update_elem(map_fd,
&profile_perf_event_cnt,
&pmu_fd, BPF_ANY) ||
ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0)) {
close(pmu_fd);
return -1;
}
profile_perf_events[profile_perf_event_cnt++] = pmu_fd;
return 0;
}
static int profile_open_perf_events(struct profiler_bpf *obj)
{
unsigned int cpu, m;
int map_fd, pmu_fd;
int map_fd;
profile_perf_events = calloc(
sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric);
@ -2255,17 +2283,11 @@ static int profile_open_perf_events(struct profiler_bpf *obj)
if (!metrics[m].selected)
continue;
for (cpu = 0; cpu < obj->rodata->num_cpu; cpu++) {
pmu_fd = syscall(__NR_perf_event_open, &metrics[m].attr,
-1/*pid*/, cpu, -1/*group_fd*/, 0);
if (pmu_fd < 0 ||
bpf_map_update_elem(map_fd, &profile_perf_event_cnt,
&pmu_fd, BPF_ANY) ||
ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0)) {
if (profile_open_perf_event(m, cpu, map_fd)) {
p_err("failed to create event %s on cpu %d",
metrics[m].name, cpu);
return -1;
}
profile_perf_events[profile_perf_event_cnt++] = pmu_fd;
}
}
return 0;