Messages in this thread Patch in this message |  | | From | Namhyung Kim <> | Subject | [PATCH 5/5] perf ftrace: Implement cpu and task filters in BPF | Date | Mon, 29 Nov 2021 15:18:30 -0800 |
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Honor cpu and task options to set up filters (by pid or tid) in the BPF program. For example, the following command will show latency of the mutex_lock for process 2570.
# perf ftrace latency -b -T mutex_lock -p 2570 sleep 3 # DURATION | COUNT | GRAPH | 0 - 1 us | 675 | ############################## | 1 - 2 us | 9 | | 2 - 4 us | 0 | | 4 - 8 us | 0 | | 8 - 16 us | 0 | | 16 - 32 us | 0 | | 32 - 64 us | 0 | | 64 - 128 us | 0 | | 128 - 256 us | 0 | | 256 - 512 us | 0 | | 512 - 1024 us | 0 | | 1 - 2 ms | 0 | | 2 - 4 ms | 0 | | 4 - 8 ms | 0 | | 8 - 16 ms | 0 | | 16 - 32 ms | 0 | | 32 - 64 ms | 0 | | 64 - 128 ms | 0 | | 128 - 256 ms | 0 | | 256 - 512 ms | 0 | | 512 - 1024 ms | 0 | | 1 - ... s | 0 | |
Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/util/bpf_ftrace.c | 41 +++++++++++++++++++++ tools/perf/util/bpf_skel/func_latency.bpf.c | 21 +++++++++++ 2 files changed, 62 insertions(+)
diff --git a/tools/perf/util/bpf_ftrace.c b/tools/perf/util/bpf_ftrace.c index 1975a6fe73c9..18d6f1558163 100644 --- a/tools/perf/util/bpf_ftrace.c +++ b/tools/perf/util/bpf_ftrace.c @@ -6,7 +6,10 @@ #include <linux/err.h> #include "util/ftrace.h" +#include "util/cpumap.h" +#include "util/thread_map.h" #include "util/debug.h" +#include "util/evlist.h" #include "util/bpf_counter.h" #include "util/bpf_skel/func_latency.skel.h" @@ -16,6 +19,7 @@ static struct func_latency_bpf *skel; int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace) { int fd, err; + int i, ncpus = 1, ntasks = 1; struct filter_entry *func; struct bpf_link *begin_link, *end_link; @@ -33,6 +37,17 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace) return -1; } + /* don't need to set cpu filter for system-wide mode */ + if (ftrace->target.cpu_list) { + ncpus = perf_cpu_map__nr(ftrace->evlist->core.cpus); + bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus); + } + + if (target__has_task(&ftrace->target) || target__none(&ftrace->target)) { + ntasks = perf_thread_map__nr(ftrace->evlist->core.threads); + bpf_map__set_max_entries(skel->maps.task_filter, ntasks); + } + set_max_rlimit(); err = func_latency_bpf__load(skel); @@ -41,6 +56,32 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace) goto out; } + if (ftrace->target.cpu_list) { + u32 cpu; + u8 val = 1; + + skel->bss->has_cpu = 1; + fd = bpf_map__fd(skel->maps.cpu_filter); + + for (i = 0; i < ncpus; i++) { + cpu = cpu_map__cpu(ftrace->evlist->core.cpus, i); + bpf_map_update_elem(fd, &cpu, &val, BPF_ANY); + } + } + + if (target__has_task(&ftrace->target) || target__none(&ftrace->target)) { + u32 pid; + u8 val = 1; + + skel->bss->has_task = 1; + fd = bpf_map__fd(skel->maps.task_filter); + + for (i = 0; i < ntasks; i++) { + pid = perf_thread_map__pid(ftrace->evlist->core.threads, i); + bpf_map_update_elem(fd, &pid, &val, BPF_ANY); + } + } + begin_link = bpf_program__attach_kprobe(skel->progs.func_begin, false, func->name); if (IS_ERR(begin_link)) { diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c index d7d31cfeabf8..17a2a53b4f16 100644 --- a/tools/perf/util/bpf_skel/func_latency.bpf.c +++ b/tools/perf/util/bpf_skel/func_latency.bpf.c @@ -36,6 +36,8 @@ struct { int enabled = 0; +int has_cpu = 0; +int has_task = 0; SEC("kprobe/func") int BPF_PROG(func_begin) @@ -46,6 +48,25 @@ int BPF_PROG(func_begin) return 0; key = bpf_get_current_pid_tgid(); + + if (has_cpu) { + __u32 cpu = bpf_get_smp_processor_id(); + __u8 *ok; + + ok = bpf_map_lookup_elem(&cpu_filter, &cpu); + if (!ok) + return 0; + } + + if (has_task) { + __u32 pid = key & 0xffffffff; + __u8 *ok; + + ok = bpf_map_lookup_elem(&task_filter, &pid); + if (!ok) + return 0; + } + now = bpf_ktime_get_ns(); // overwrite timestamp for nested functions -- 2.34.0.rc2.393.gf8c9666880-goog
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