This is a simple demonstration of an eBPF program attached to static
trace event ("event/subsys:event"). The count and pid values here are
the values grabbed from the event hits and aggregated in a hash map.
Example output:
# ./readcounts-by-pid
^C
pid 4143 comm uname count 832 hitcount
1
pid 2755 comm gdbus count 32 hitcount
2
pid 315 comm systemd-journal count 17408 hitcount
16
pid 2415 comm dbus-daemon count 8242 hitcount
5
pid 4164 comm gdbus count 288 hitcount
18
pid 4139 comm firefox count 384245 hitcount
61
pid 2660 comm gnome-shell count 42672 hitcount
117
pid 774 comm Xorg count 4621105 hitcount
1259
pid 2072 comm upowerd count 32 hitcount
2
Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
samples/bpf/Makefile | 4 +++
samples/bpf/readcounts-by-pid_kern.c | 57 +++++++++++++++++++++++++++++++
samples/bpf/readcounts-by-pid_user.c | 66 ++++++++++++++++++++++++++++++++++++
3 files changed, 127 insertions(+)
create mode 100644 samples/bpf/readcounts-by-pid_kern.c
create mode 100644 samples/bpf/readcounts-by-pid_user.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index edd638b..d7af8d5 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -16,6 +16,7 @@ hostprogs-y += tracex5
hostprogs-y += tracex6
hostprogs-y += trace_output
hostprogs-y += lathist
+hostprogs-y += readcounts-by-pid
test_verifier-objs := test_verifier.o libbpf.o
test_maps-objs := test_maps.o libbpf.o
@@ -32,6 +33,7 @@ tracex5-objs := bpf_load.o libbpf.o tracex5_user.o
tracex6-objs := bpf_load.o libbpf.o tracex6_user.o
trace_output-objs := bpf_load.o libbpf.o trace_output_user.o
lathist-objs := bpf_load.o libbpf.o lathist_user.o
+readcounts-by-pid-objs := bpf_load.o libbpf.o readcounts-by-pid_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -47,6 +49,7 @@ always += tracex6_kern.o
always += trace_output_kern.o
always += tcbpf1_kern.o
always += lathist_kern.o
+always += readcounts-by-pid_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
@@ -63,6 +66,7 @@ HOSTLOADLIBES_tracex5 += -lelf
HOSTLOADLIBES_tracex6 += -lelf
HOSTLOADLIBES_trace_output += -lelf -lrt
HOSTLOADLIBES_lathist += -lelf
+HOSTLOADLIBES_readcounts-by-pid += -lelf
# point this to your LLVM backend with bpf support
LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc
diff --git a/samples/bpf/readcounts-by-pid_kern.c
b/samples/bpf/readcounts-by-pid_kern.c
new file mode 100644
index 0000000..5967781
--- /dev/null
+++ b/samples/bpf/readcounts-by-pid_kern.c
@@ -0,0 +1,57 @@
+/* Copyright (c) 2016 Intel Corporation
+ *
+ * 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 <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct hist_key {
+ char comm[16];
+ u64 pid;
+};
+
+struct hist_val {
+ u64 count;
+ u64 hitcount;
+};
+
+struct bpf_map_def SEC("maps") counts_map = {
+ .type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(struct hist_key),
+ .value_size = sizeof(struct hist_val),
+ .max_entries = 1024,
+};
+
+SEC("event/syscalls:sys_enter_read")
+int bpf_prog(void *ctx)
+{
+ struct hist_key key = {};
+ struct hist_val init_val;
+ struct hist_val *val;
+ u64 count;
+
+ char common_pid_field_name1[] = "common_pid";
+ key.pid = bpf_trace_event_field_read(ctx, common_pid_field_name1);
+
+ bpf_get_current_comm(&key.comm, sizeof(key.comm));
+
+ char count_field_name1[] = "count";
+ count = bpf_trace_event_field_read(ctx, count_field_name1);
+
+ val = bpf_map_lookup_elem(&counts_map, &key);
+ if (val) {
+ val->count += count;
+ val->hitcount += 1;
+ } else {
+ init_val.count = count;
+ init_val.hitcount = 1;
+ bpf_map_update_elem(&counts_map, &key, &init_val, BPF_ANY);
+ }
+ return 1;
+}
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/samples/bpf/readcounts-by-pid_user.c
b/samples/bpf/readcounts-by-pid_user.c
new file mode 100644
index 0000000..d08b867
--- /dev/null
+++ b/samples/bpf/readcounts-by-pid_user.c
@@ -0,0 +1,66 @@
+/* Copyright (c) 2016 Intel Corporation
+ *
+ * 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 <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+
+struct hist_key {
+ char comm[16];
+ __u64 pid;
+};
+
+struct hist_val {
+ __u64 count;
+ __u64 hitcount;
+};
+
+static void print_hist(int fd)
+{
+ struct hist_key key = {}, next_key;
+ struct hist_val val;
+
+ printf("\n");
+
+ while (bpf_get_next_key(fd, &key, &next_key) == 0) {
+ bpf_lookup_elem(fd, &next_key, &val);
+ printf("pid %8llu comm %-16s count %12llu hitcount
%12llu\n",
+ next_key.pid, next_key.comm, val.count, val.hitcount);
+ key = next_key;
+ }
+}
+
+static void int_exit(int sig)
+{
+ print_hist(map_fd[0]);
+
+ exit(0);
+}
+
+int main(int ac, char **argv)
+{
+ char filename[256];
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ signal(SIGINT, int_exit);
+
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ for (;;) {
+ sleep(60);
+ }
+
+ return 0;
+}
--
1.9.3
