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authorAndrii Nakryiko <andriin@fb.com>2020-01-13 10:31:42 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-01-14 04:48:13 +0300
commit9c01546d26d28cf57341d8380ba900bf68e26b18 (patch)
tree06640835fe8f1d79e93687db289bcf8451548380 /tools/bpf/runqslower
parent1cf5b23988ea0086a252a5c8b005b075f1e9b030 (diff)
downloadlinux-9c01546d26d28cf57341d8380ba900bf68e26b18.tar.xz
tools/bpf: Add runqslower tool to tools/bpf
Convert one of BCC tools (runqslower [0]) to BPF CO-RE + libbpf. It matches its BCC-based counterpart 1-to-1, supporting all the same parameters and functionality. runqslower tool utilizes BPF skeleton, auto-generated from BPF object file, as well as memory-mapped interface to global (read-only, in this case) data. Its Makefile also ensures auto-generation of "relocatable" vmlinux.h, which is necessary for BTF-typed raw tracepoints with direct memory access. [0] https://github.com/iovisor/bcc/blob/11bf5d02c895df9646c117c713082eb192825293/tools/runqslower.py Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200113073143.1779940-6-andriin@fb.com
Diffstat (limited to 'tools/bpf/runqslower')
-rw-r--r--tools/bpf/runqslower/.gitignore1
-rw-r--r--tools/bpf/runqslower/Makefile80
-rw-r--r--tools/bpf/runqslower/runqslower.bpf.c100
-rw-r--r--tools/bpf/runqslower/runqslower.c187
-rw-r--r--tools/bpf/runqslower/runqslower.h13
5 files changed, 381 insertions, 0 deletions
diff --git a/tools/bpf/runqslower/.gitignore b/tools/bpf/runqslower/.gitignore
new file mode 100644
index 000000000000..90a456a2a72f
--- /dev/null
+++ b/tools/bpf/runqslower/.gitignore
@@ -0,0 +1 @@
+/.output
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
new file mode 100644
index 000000000000..f1363ae8e473
--- /dev/null
+++ b/tools/bpf/runqslower/Makefile
@@ -0,0 +1,80 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+OUTPUT := .output
+CLANG := clang
+LLC := llc
+LLVM_STRIP := llvm-strip
+DEFAULT_BPFTOOL := $(OUTPUT)/sbin/bpftool
+BPFTOOL ?= $(DEFAULT_BPFTOOL)
+LIBBPF_SRC := $(abspath ../../lib/bpf)
+CFLAGS := -g -Wall
+
+# Try to detect best kernel BTF source
+KERNEL_REL := $(shell uname -r)
+ifneq ("$(wildcard /sys/kenerl/btf/vmlinux)","")
+VMLINUX_BTF := /sys/kernel/btf/vmlinux
+else ifneq ("$(wildcard /boot/vmlinux-$(KERNEL_REL))","")
+VMLINUX_BTF := /boot/vmlinux-$(KERNEL_REL)
+else
+$(error "Can't detect kernel BTF, use VMLINUX_BTF to specify it explicitly")
+endif
+
+abs_out := $(abspath $(OUTPUT))
+ifeq ($(V),1)
+Q =
+msg =
+else
+Q = @
+msg = @printf ' %-8s %s%s\n' "$(1)" "$(notdir $(2))" "$(if $(3), $(3))";
+MAKEFLAGS += --no-print-directory
+submake_extras := feature_display=0
+endif
+
+.DELETE_ON_ERROR:
+
+.PHONY: all clean runqslower
+all: runqslower
+
+runqslower: $(OUTPUT)/runqslower
+
+clean:
+ $(call msg,CLEAN)
+ $(Q)rm -rf $(OUTPUT) runqslower
+
+$(OUTPUT)/runqslower: $(OUTPUT)/runqslower.o $(OUTPUT)/libbpf.a
+ $(call msg,BINARY,$@)
+ $(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@
+
+$(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h \
+ $(OUTPUT)/runqslower.bpf.o
+
+$(OUTPUT)/runqslower.bpf.o: $(OUTPUT)/vmlinux.h runqslower.h
+
+$(OUTPUT)/%.skel.h: $(OUTPUT)/%.bpf.o | $(BPFTOOL)
+ $(call msg,GEN-SKEL,$@)
+ $(Q)$(BPFTOOL) gen skeleton $< > $@
+
+$(OUTPUT)/%.bpf.o: %.bpf.c $(OUTPUT)/libbpf.a | $(OUTPUT)
+ $(call msg,BPF,$@)
+ $(Q)$(CLANG) -g -O2 -target bpf -I$(OUTPUT) -I$(LIBBPF_SRC) \
+ -c $(filter %.c,$^) -o $@ && \
+ $(LLVM_STRIP) -g $@
+
+$(OUTPUT)/%.o: %.c | $(OUTPUT)
+ $(call msg,CC,$@)
+ $(Q)$(CC) $(CFLAGS) -I$(LIBBPF_SRC) -I$(OUTPUT) -c $(filter %.c,$^) -o $@
+
+$(OUTPUT):
+ $(call msg,MKDIR,$@)
+ $(Q)mkdir -p $(OUTPUT)
+
+$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF) | $(OUTPUT) $(BPFTOOL)
+ $(call msg,GEN,$@)
+ $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+
+$(OUTPUT)/libbpf.a: | $(OUTPUT)
+ $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) \
+ OUTPUT=$(abs_out)/ $(abs_out)/libbpf.a
+
+$(DEFAULT_BPFTOOL):
+ $(Q)$(MAKE) $(submake_extras) -C ../bpftool \
+ prefix= OUTPUT=$(abs_out)/ DESTDIR=$(abs_out) install
diff --git a/tools/bpf/runqslower/runqslower.bpf.c b/tools/bpf/runqslower/runqslower.bpf.c
new file mode 100644
index 000000000000..623cce4d37f5
--- /dev/null
+++ b/tools/bpf/runqslower/runqslower.bpf.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include "vmlinux.h"
+#include <bpf_helpers.h>
+#include "runqslower.h"
+
+#define TASK_RUNNING 0
+
+#define BPF_F_INDEX_MASK 0xffffffffULL
+#define BPF_F_CURRENT_CPU BPF_F_INDEX_MASK
+
+const volatile __u64 min_us = 0;
+const volatile pid_t targ_pid = 0;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 10240);
+ __type(key, u32);
+ __type(value, u64);
+} start SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(u32));
+ __uint(value_size, sizeof(u32));
+} events SEC(".maps");
+
+/* record enqueue timestamp */
+__always_inline
+static int trace_enqueue(u32 tgid, u32 pid)
+{
+ u64 ts;
+
+ if (!pid || (targ_pid && targ_pid != pid))
+ return 0;
+
+ ts = bpf_ktime_get_ns();
+ bpf_map_update_elem(&start, &pid, &ts, 0);
+ return 0;
+}
+
+SEC("tp_btf/sched_wakeup")
+int handle__sched_wakeup(u64 *ctx)
+{
+ /* TP_PROTO(struct task_struct *p) */
+ struct task_struct *p = (void *)ctx[0];
+
+ return trace_enqueue(p->tgid, p->pid);
+}
+
+SEC("tp_btf/sched_wakeup_new")
+int handle__sched_wakeup_new(u64 *ctx)
+{
+ /* TP_PROTO(struct task_struct *p) */
+ struct task_struct *p = (void *)ctx[0];
+
+ return trace_enqueue(p->tgid, p->pid);
+}
+
+SEC("tp_btf/sched_switch")
+int handle__sched_switch(u64 *ctx)
+{
+ /* TP_PROTO(bool preempt, struct task_struct *prev,
+ * struct task_struct *next)
+ */
+ struct task_struct *prev = (struct task_struct *)ctx[1];
+ struct task_struct *next = (struct task_struct *)ctx[2];
+ struct event event = {};
+ u64 *tsp, delta_us;
+ long state;
+ u32 pid;
+
+ /* ivcsw: treat like an enqueue event and store timestamp */
+ if (prev->state == TASK_RUNNING)
+ trace_enqueue(prev->tgid, prev->pid);
+
+ pid = next->pid;
+
+ /* fetch timestamp and calculate delta */
+ tsp = bpf_map_lookup_elem(&start, &pid);
+ if (!tsp)
+ return 0; /* missed enqueue */
+
+ delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
+ if (min_us && delta_us <= min_us)
+ return 0;
+
+ event.pid = pid;
+ event.delta_us = delta_us;
+ bpf_get_current_comm(&event.task, sizeof(event.task));
+
+ /* output */
+ bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
+ &event, sizeof(event));
+
+ bpf_map_delete_elem(&start, &pid);
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/bpf/runqslower/runqslower.c b/tools/bpf/runqslower/runqslower.c
new file mode 100644
index 000000000000..996f0e2c560e
--- /dev/null
+++ b/tools/bpf/runqslower/runqslower.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+// Copyright (c) 2019 Facebook
+#include <argp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <time.h>
+#include <libbpf.h>
+#include <bpf.h>
+#include "runqslower.h"
+#include "runqslower.skel.h"
+
+struct env {
+ pid_t pid;
+ __u64 min_us;
+ bool verbose;
+} env = {
+ .min_us = 10000,
+};
+
+const char *argp_program_version = "runqslower 0.1";
+const char *argp_program_bug_address = "<bpf@vger.kernel.org>";
+const char argp_program_doc[] =
+"runqslower Trace long process scheduling delays.\n"
+" For Linux, uses eBPF, BPF CO-RE, libbpf, BTF.\n"
+"\n"
+"This script traces high scheduling delays between tasks being\n"
+"ready to run and them running on CPU after that.\n"
+"\n"
+"USAGE: runqslower [-p PID] [min_us]\n"
+"\n"
+"EXAMPLES:\n"
+" runqslower # trace run queue latency higher than 10000 us (default)\n"
+" runqslower 1000 # trace run queue latency higher than 1000 us\n"
+" runqslower -p 123 # trace pid 123 only\n";
+
+static const struct argp_option opts[] = {
+ { "pid", 'p', "PID", 0, "Process PID to trace"},
+ { "verbose", 'v', NULL, 0, "Verbose debug output" },
+ {},
+};
+
+static error_t parse_arg(int key, char *arg, struct argp_state *state)
+{
+ static int pos_args;
+ int pid;
+ long long min_us;
+
+ switch (key) {
+ case 'v':
+ env.verbose = true;
+ break;
+ case 'p':
+ errno = 0;
+ pid = strtol(arg, NULL, 10);
+ if (errno || pid <= 0) {
+ fprintf(stderr, "Invalid PID: %s\n", arg);
+ argp_usage(state);
+ }
+ env.pid = pid;
+ break;
+ case ARGP_KEY_ARG:
+ if (pos_args++) {
+ fprintf(stderr,
+ "Unrecognized positional argument: %s\n", arg);
+ argp_usage(state);
+ }
+ errno = 0;
+ min_us = strtoll(arg, NULL, 10);
+ if (errno || min_us <= 0) {
+ fprintf(stderr, "Invalid delay (in us): %s\n", arg);
+ argp_usage(state);
+ }
+ env.min_us = min_us;
+ break;
+ default:
+ return ARGP_ERR_UNKNOWN;
+ }
+ return 0;
+}
+
+int libbpf_print_fn(enum libbpf_print_level level,
+ const char *format, va_list args)
+{
+ if (level == LIBBPF_DEBUG && !env.verbose)
+ return 0;
+ return vfprintf(stderr, format, args);
+}
+
+static int bump_memlock_rlimit(void)
+{
+ struct rlimit rlim_new = {
+ .rlim_cur = RLIM_INFINITY,
+ .rlim_max = RLIM_INFINITY,
+ };
+
+ return setrlimit(RLIMIT_MEMLOCK, &rlim_new);
+}
+
+void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
+{
+ const struct event *e = data;
+ struct tm *tm;
+ char ts[32];
+ time_t t;
+
+ time(&t);
+ tm = localtime(&t);
+ strftime(ts, sizeof(ts), "%H:%M:%S", tm);
+ printf("%-8s %-16s %-6d %14llu\n", ts, e->task, e->pid, e->delta_us);
+}
+
+void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
+{
+ printf("Lost %llu events on CPU #%d!\n", lost_cnt, cpu);
+}
+
+int main(int argc, char **argv)
+{
+ static const struct argp argp = {
+ .options = opts,
+ .parser = parse_arg,
+ .doc = argp_program_doc,
+ };
+ struct perf_buffer_opts pb_opts;
+ struct perf_buffer *pb = NULL;
+ struct runqslower_bpf *obj;
+ int err;
+
+ err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
+ if (err)
+ return err;
+
+ libbpf_set_print(libbpf_print_fn);
+
+ err = bump_memlock_rlimit();
+ if (err) {
+ fprintf(stderr, "failed to increase rlimit: %d", err);
+ return 1;
+ }
+
+ obj = runqslower_bpf__open();
+ if (!obj) {
+ fprintf(stderr, "failed to open and/or load BPF object\n");
+ return 1;
+ }
+
+ /* initialize global data (filtering options) */
+ obj->rodata->targ_pid = env.pid;
+ obj->rodata->min_us = env.min_us;
+
+ err = runqslower_bpf__load(obj);
+ if (err) {
+ fprintf(stderr, "failed to load BPF object: %d\n", err);
+ goto cleanup;
+ }
+
+ err = runqslower_bpf__attach(obj);
+ if (err) {
+ fprintf(stderr, "failed to attach BPF programs\n");
+ goto cleanup;
+ }
+
+ printf("Tracing run queue latency higher than %llu us\n", env.min_us);
+ printf("%-8s %-16s %-6s %14s\n", "TIME", "COMM", "PID", "LAT(us)");
+
+ pb_opts.sample_cb = handle_event;
+ pb_opts.lost_cb = handle_lost_events;
+ pb = perf_buffer__new(bpf_map__fd(obj->maps.events), 64, &pb_opts);
+ err = libbpf_get_error(pb);
+ if (err) {
+ pb = NULL;
+ fprintf(stderr, "failed to open perf buffer: %d\n", err);
+ goto cleanup;
+ }
+
+ while ((err = perf_buffer__poll(pb, 100)) >= 0)
+ ;
+ printf("Error polling perf buffer: %d\n", err);
+
+cleanup:
+ perf_buffer__free(pb);
+ runqslower_bpf__destroy(obj);
+
+ return err != 0;
+}
diff --git a/tools/bpf/runqslower/runqslower.h b/tools/bpf/runqslower/runqslower.h
new file mode 100644
index 000000000000..9db225425e5f
--- /dev/null
+++ b/tools/bpf/runqslower/runqslower.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __RUNQSLOWER_H
+#define __RUNQSLOWER_H
+
+#define TASK_COMM_LEN 16
+
+struct event {
+ char task[TASK_COMM_LEN];
+ __u64 delta_us;
+ pid_t pid;
+};
+
+#endif /* __RUNQSLOWER_H */