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libbpf-tools: add llcstat
Signed-off-by: Wenbo Zhang <[email protected]>
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‎libbpf-tools/.gitignore

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/execsnoop
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/filelife
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/hardirqs
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/llcstat
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/numamove
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/opensnoop
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/readahead

‎libbpf-tools/Makefile

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@@ -20,6 +20,7 @@ APPS = \
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execsnoop \
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filelife \
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hardirqs \
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llcstat \
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numamove \
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opensnoop \
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readahead \

‎libbpf-tools/llcstat.bpf.c

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// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2020 Wenbo Zhang
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "llcstat.h"
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#define MAX_ENTRIES 10240
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, MAX_ENTRIES);
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__type(key, u64);
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__type(value, struct info);
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} infos SEC(".maps");
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static __always_inline
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int trace_event(__u64 sample_period, bool miss)
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{
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u64 pid = bpf_get_current_pid_tgid();
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u32 cpu = bpf_get_smp_processor_id();
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struct info *infop, info = {};
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u64 key = pid << 32 | cpu;
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infop = bpf_map_lookup_elem(&infos, &key);
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if (!infop) {
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bpf_get_current_comm(info.comm, sizeof(info.comm));
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infop = &info;
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}
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if (miss)
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infop->miss += sample_period;
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else
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infop->ref += sample_period;
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if (infop == &info)
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bpf_map_update_elem(&infos, &key, infop, 0);
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return 0;
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}
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SEC("perf_event/1")
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int on_cache_miss(struct bpf_perf_event_data *ctx)
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{
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return trace_event(ctx->sample_period, true);
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}
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SEC("perf_event/2")
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int on_cache_ref(struct bpf_perf_event_data *ctx)
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{
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return trace_event(ctx->sample_period, false);
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}
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char LICENSE[] SEC("license") = "GPL";

‎libbpf-tools/llcstat.c

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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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// Copyright (c) 2020 Wenbo Zhang
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//
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// Based on llcstat(8) from BCC by Teng Qin.
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// 29-Sep-2020 Wenbo Zhang Created this.
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#include <argp.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <linux/perf_event.h>
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#include <asm/unistd.h>
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#include <bpf/libbpf.h>
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#include <bpf/bpf.h>
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#include "llcstat.h"
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#include "llcstat.skel.h"
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#include "trace_helpers.h"
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struct env {
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int sample_period;
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time_t duration;
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bool verbose;
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} env = {
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.sample_period = 100,
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.duration = 10,
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};
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static volatile bool exiting;
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const char *argp_program_version = "llcstat 0.1";
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const char *argp_program_bug_address = "<[email protected]>";
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const char argp_program_doc[] =
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"Summarize cache references and misses by PID.\n"
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"\n"
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"USAGE: llcstat [--help] [-c SAMPLE_PERIOD] [duration]\n";
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static const struct argp_option opts[] = {
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{ "sample_period", 'c', "SAMPLE_PERIOD", 0, "Sample one in this many "
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"number of cache reference / miss events" },
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{ "verbose", 'v', NULL, 0, "Verbose debug output" },
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{},
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};
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static error_t parse_arg(int key, char *arg, struct argp_state *state)
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{
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static int pos_args;
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switch (key) {
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case 'v':
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env.verbose = true;
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break;
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case 'c':
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errno = 0;
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env.sample_period = strtol(arg, NULL, 10);
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if (errno) {
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fprintf(stderr, "invalid sample period\n");
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argp_usage(state);
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}
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break;
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case ARGP_KEY_ARG:
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if (pos_args++) {
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fprintf(stderr,
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"unrecognized positional argument: %s\n", arg);
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argp_usage(state);
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}
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errno = 0;
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env.duration = strtol(arg, NULL, 10);
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if (errno) {
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fprintf(stderr, "invalid duration\n");
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argp_usage(state);
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}
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break;
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default:
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return ARGP_ERR_UNKNOWN;
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}
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return 0;
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}
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static int nr_cpus;
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static int open_and_attach_perf_event(__u64 config, int period,
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struct bpf_program *prog,
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struct bpf_link *links[])
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{
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struct perf_event_attr attr = {
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.type = PERF_TYPE_HARDWARE,
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.freq = 0,
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.sample_period = period,
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.config = config,
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};
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int i, fd;
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for (i = 0; i < nr_cpus; i++) {
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fd = syscall(__NR_perf_event_open, &attr, -1, i, -1, 0);
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if (fd < 0) {
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fprintf(stderr, "failed to init perf sampling: %s\n",
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strerror(errno));
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return -1;
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}
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links[i] = bpf_program__attach_perf_event(prog, fd);
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if (libbpf_get_error(links[i])) {
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fprintf(stderr, "failed to attach perf event on cpu: "
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"%d\n", i);
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links[i] = NULL;
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close(fd);
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return -1;
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}
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}
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return 0;
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}
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int libbpf_print_fn(enum libbpf_print_level level,
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const char *format, va_list args)
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{
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if (level == LIBBPF_DEBUG && !env.verbose)
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return 0;
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return vfprintf(stderr, format, args);
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}
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static void sig_handler(int sig)
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{
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exiting = true;
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}
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static void print_map(struct bpf_map *map)
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{
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__u64 total_ref = 0, total_miss = 0, total_hit, hit;
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__u64 lookup_key = -1, next_key;
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int err, fd = bpf_map__fd(map);
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struct info info;
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__u32 pid, cpu;
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while (!bpf_map_get_next_key(fd, &lookup_key, &next_key)) {
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err = bpf_map_lookup_elem(fd, &next_key, &info);
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if (err < 0) {
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fprintf(stderr, "failed to lookup infos: %d\n", err);
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return;
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}
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hit = info.ref > info.miss ? info.ref - info.miss : 0;
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pid = next_key >> 32;
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cpu = next_key;
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printf("%-8u %-16s %-4u %12llu %12llu %6.2f%%\n", pid, info.comm,
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cpu, info.ref, info.miss, info.ref > 0 ?
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hit * 1.0 / info.ref * 100 : 0);
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total_miss += info.miss;
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total_ref += info.ref;
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lookup_key = next_key;
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}
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total_hit = total_ref > total_miss ? total_ref - total_miss : 0;
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printf("Total References: %llu Total Misses: %llu Hit Rate: %.2f%%\n",
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total_ref, total_miss, total_ref > 0 ?
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total_hit * 1.0 / total_ref * 100 : 0);
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lookup_key = -1;
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while (!bpf_map_get_next_key(fd, &lookup_key, &next_key)) {
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err = bpf_map_delete_elem(fd, &next_key);
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if (err < 0) {
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fprintf(stderr, "failed to cleanup infos: %d\n", err);
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return;
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}
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lookup_key = next_key;
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}
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}
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int main(int argc, char **argv)
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{
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struct bpf_link **rlinks = NULL, **mlinks = NULL;
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static const struct argp argp = {
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.options = opts,
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.parser = parse_arg,
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.doc = argp_program_doc,
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};
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struct llcstat_bpf *obj;
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int err, i;
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err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
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if (err)
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return err;
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libbpf_set_print(libbpf_print_fn);
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err = bump_memlock_rlimit();
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if (err) {
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fprintf(stderr, "failed to increase rlimit: %d\n", err);
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return 1;
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}
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obj = llcstat_bpf__open();
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if (!obj) {
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fprintf(stderr, "failed to open and/or load BPF object\n");
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return 1;
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}
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nr_cpus = libbpf_num_possible_cpus();
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mlinks = calloc(nr_cpus, sizeof(*mlinks));
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rlinks = calloc(nr_cpus, sizeof(*rlinks));
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if (!mlinks || !rlinks) {
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fprintf(stderr, "failed to alloc mlinks or rlinks\n");
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goto cleanup;
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}
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err = llcstat_bpf__load(obj);
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if (err) {
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fprintf(stderr, "failed to load BPF object: %d\n", err);
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goto cleanup;
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}
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if (open_and_attach_perf_event(PERF_COUNT_HW_CACHE_MISSES,
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env.sample_period,
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obj->progs.on_cache_miss, mlinks))
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goto cleanup;
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if (open_and_attach_perf_event(PERF_COUNT_HW_CACHE_REFERENCES,
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env.sample_period,
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obj->progs.on_cache_ref, rlinks))
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goto cleanup;
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printf("Running for %ld seconds or Hit Ctrl-C to end.\n", env.duration);
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signal(SIGINT, sig_handler);
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sleep(env.duration);
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printf("%-8s %-16s %-4s %12s %12s %7s\n",
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"PID", "NAME", "CPU", "REFERENCE", "MISS", "HIT%");
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print_map(obj->maps.infos);
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cleanup:
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for (i = 0; i < nr_cpus; i++) {
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bpf_link__destroy(mlinks[i]);
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bpf_link__destroy(rlinks[i]);
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}
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free(mlinks);
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free(rlinks);
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llcstat_bpf__destroy(obj);
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return err != 0;
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}

‎libbpf-tools/llcstat.h

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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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#ifndef __LLCSTAT_H
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#define __LLCSTAT_H
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#define TASK_COMM_LEN 16
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struct info {
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__u64 ref;
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__u64 miss;
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char comm[TASK_COMM_LEN];
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};
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#endif /* __LLCSTAT_H */

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