@@ -61,3 +61,4 @@ iperf.*
/vmlinux.h
/bpftool/
/libbpf/
+irqlat
@@ -60,6 +60,8 @@ tprogs-y += xdp_redirect_map
tprogs-y += xdp_redirect
tprogs-y += xdp_monitor
+tprogs-y += irqlat
+
# Libbpf dependencies
LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf
LIBBPF_OUTPUT = $(abspath $(BPF_SAMPLES_PATH))/libbpf
@@ -125,6 +127,8 @@ xdp_redirect_map-objs := xdp_redirect_map_user.o $(XDP_SAMPLE)
xdp_redirect-objs := xdp_redirect_user.o $(XDP_SAMPLE)
xdp_monitor-objs := xdp_monitor_user.o $(XDP_SAMPLE)
+irqlat-objs := irqlat_user.o
+
# Tell kbuild to always build the programs
always-y := $(tprogs-y)
always-y += sockex1_kern.o
@@ -181,6 +185,7 @@ always-y += ibumad_kern.o
always-y += hbm_out_kern.o
always-y += hbm_edt_kern.o
always-y += xdpsock_kern.o
+always-y += irqlat_kern.o
ifeq ($(ARCH), arm)
# Strip all except -D__LINUX_ARM_ARCH__ option needed to handle linux
new file mode 100644
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Kylin
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/version.h>
+#include <linux/ptrace.h>
+#include <uapi/linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+#define MAX_CPUS 128
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, int);
+ __type(value, u64);
+ __uint(max_entries, MAX_CPUS);
+} irq_ts SEC(".maps");
+
+SEC("tracepoint/irq/irq_handler_entry")
+int on_irq_entry(struct pt_regs *ctx)
+{
+ int cpu = bpf_get_smp_processor_id();
+ u64 *ts = bpf_map_lookup_elem(&irq_ts, &cpu);
+
+ if (ts)
+ *ts = bpf_ktime_get_ns();
+
+ return 0;
+}
+
+struct datares {
+ u64 entries;
+ u64 total;
+ u64 max;
+ u64 min;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, int);
+ __type(value, struct datares);
+ __uint(max_entries, MAX_CPUS);
+} irq_lat SEC(".maps");
+
+SEC("tracepoint/irq/irq_handler_exit")
+int on_irq_exit(struct pt_regs *ctx)
+{
+ u64 *ts, cur_ts, delta, *val;
+ int cpu;
+ struct datares *res;
+
+ cpu = bpf_get_smp_processor_id();
+ ts = bpf_map_lookup_elem(&irq_ts, &cpu);
+ if (!ts)
+ return 0;
+
+ cur_ts = bpf_ktime_get_ns();
+ delta = cur_ts - *ts;
+
+ res = bpf_map_lookup_elem(&irq_lat, &cpu);
+ if (!res)
+ return 0;
+
+ res->entries++;
+ res->total += delta;
+ if (res->max < delta)
+ res->max = delta;
+ if (res->min == 0 || res->min > delta)
+ res->min = delta;
+
+ if (res->total >= U64_MAX)
+ __builtin_memset(res, 0, sizeof(struct datares));
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
new file mode 100644
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Kylin
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <linux/perf_event.h>
+#include <linux/bpf.h>
+#include <bpf/libbpf.h>
+#include <bpf/bpf.h>
+#include "trace_helpers.h"
+
+#define MAX_CPUS 128
+static int map_fd[2];
+
+struct datares {
+ __u64 entries;
+ __u64 total;
+ __u64 max;
+ __u64 min;
+};
+
+static void get_data(int fd)
+{
+ int i;
+ struct datares res;
+ __u64 avg;
+
+ /* Clear screen */
+ printf("\033[2J");
+
+ /* Header */
+ printf("\nirq Latency statistics: (ns)\n");
+ for (i = 0; i < MAX_CPUS; i++) {
+ bpf_map_lookup_elem(fd, &i, &res);
+
+ if (res.entries == 0)
+ continue;
+
+ avg = res.total / res.entries;
+ printf("cpu:%d, max:%llu, min:%llu, avg:%llu\n",
+ i, res.max, res.min, avg);
+ }
+}
+
+int main(int argc, char **argv)
+{
+ char filename[256];
+ struct bpf_object *obj = NULL;
+ struct bpf_link *links[2];
+ struct bpf_program *prog;
+ int delay = 1, i = 0;
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ obj = bpf_object__open_file(filename, NULL);
+ if (libbpf_get_error(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ obj = NULL;
+ goto cleanup;
+ }
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ map_fd[0] = bpf_object__find_map_fd_by_name(obj, "irq_ts");
+ map_fd[1] = bpf_object__find_map_fd_by_name(obj, "irq_lat");
+ if (map_fd[0] < 0 || map_fd[1] < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
+ bpf_object__for_each_program(prog, obj) {
+ links[i] = bpf_program__attach(prog);
+ if (libbpf_get_error(links[i])) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ links[i] = NULL;
+ goto cleanup;
+ }
+ i++;
+ }
+
+ while (1) {
+ sleep(delay);
+ get_data(map_fd[1]);
+ }
+
+cleanup:
+ for (i--; i >= 0; i--)
+ bpf_link__destroy(links[i]);
+
+ bpf_object__close(obj);
+ return 0;
+}
irqlat presents max, min and avg value of time consumed in irq handling for each cpu, from irq_handler_entry to irq_handler_exit. engineers can run it to evaluate the performance of irq handling, especially for RT system. Signed-off-by: Song Chen <chensong_2000@189.cn> --- samples/bpf/.gitignore | 1 + samples/bpf/Makefile | 5 ++ samples/bpf/irqlat_kern.c | 81 ++++++++++++++++++++++++++++++ samples/bpf/irqlat_user.c | 100 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 187 insertions(+) create mode 100644 samples/bpf/irqlat_kern.c create mode 100644 samples/bpf/irqlat_user.c