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Date: Fri, 31 Jul 2015 11:59:30 +0000
From: Kaixu Xia <xiakaixu@...wei.com>
To: <ast@...mgrid.com>, <davem@...emloft.net>, <acme@...nel.org>,
<mingo@...hat.com>, <a.p.zijlstra@...llo.nl>,
<masami.hiramatsu.pt@...achi.com>, <jolsa@...nel.org>,
<daniel@...earbox.net>
CC: <xiakaixu@...wei.com>, <wangnan0@...wei.com>,
<linux-kernel@...r.kernel.org>, <pi3orama@....com>,
<hekuang@...wei.com>, <netdev@...r.kernel.org>
Subject: [PATCH v5 4/4] samples/bpf: example of get selected PMU counter value
This is a simple example and shows how to use the new ability
to get the selected Hardware PMU counter value.
Signed-off-by: Kaixu Xia <xiakaixu@...wei.com>
---
samples/bpf/Makefile | 4 +++
samples/bpf/bpf_helpers.h | 2 ++
samples/bpf/tracex6_kern.c | 26 ++++++++++++++++++
samples/bpf/tracex6_user.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 100 insertions(+)
create mode 100644 samples/bpf/tracex6_kern.c
create mode 100644 samples/bpf/tracex6_user.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 4450fed..63e7d50 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -12,6 +12,7 @@ hostprogs-y += tracex2
hostprogs-y += tracex3
hostprogs-y += tracex4
hostprogs-y += tracex5
+hostprogs-y += tracex6
hostprogs-y += lathist
test_verifier-objs := test_verifier.o libbpf.o
@@ -25,6 +26,7 @@ tracex2-objs := bpf_load.o libbpf.o tracex2_user.o
tracex3-objs := bpf_load.o libbpf.o tracex3_user.o
tracex4-objs := bpf_load.o libbpf.o tracex4_user.o
tracex5-objs := bpf_load.o libbpf.o tracex5_user.o
+tracex6-objs := bpf_load.o libbpf.o tracex6_user.o
lathist-objs := bpf_load.o libbpf.o lathist_user.o
# Tell kbuild to always build the programs
@@ -37,6 +39,7 @@ always += tracex2_kern.o
always += tracex3_kern.o
always += tracex4_kern.o
always += tracex5_kern.o
+always += tracex6_kern.o
always += tcbpf1_kern.o
always += lathist_kern.o
@@ -51,6 +54,7 @@ HOSTLOADLIBES_tracex2 += -lelf
HOSTLOADLIBES_tracex3 += -lelf
HOSTLOADLIBES_tracex4 += -lelf -lrt
HOSTLOADLIBES_tracex5 += -lelf
+HOSTLOADLIBES_tracex6 += -lelf
HOSTLOADLIBES_lathist += -lelf
# point this to your LLVM backend with bpf support
diff --git a/samples/bpf/bpf_helpers.h b/samples/bpf/bpf_helpers.h
index bdf1c16..c8a3594 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -31,6 +31,8 @@ static unsigned long long (*bpf_get_current_uid_gid)(void) =
(void *) BPF_FUNC_get_current_uid_gid;
static int (*bpf_get_current_comm)(void *buf, int buf_size) =
(void *) BPF_FUNC_get_current_comm;
+static int (*bpf_perf_event_read)(void *map, int index) =
+ (void *) BPF_FUNC_perf_event_read;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions
diff --git a/samples/bpf/tracex6_kern.c b/samples/bpf/tracex6_kern.c
new file mode 100644
index 0000000..23d1cff
--- /dev/null
+++ b/samples/bpf/tracex6_kern.c
@@ -0,0 +1,26 @@
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") my_map = {
+ .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(u32),
+ .max_entries = 32,
+};
+
+SEC("kprobe/sys_write")
+int bpf_prog1(struct pt_regs *ctx)
+{
+ u64 count;
+ u32 key = bpf_get_smp_processor_id();
+ char fmt[] = "CPU-%d %llu\n";
+
+ count = bpf_perf_event_read(&my_map, key);
+ bpf_trace_printk(fmt, sizeof(fmt), key, count);
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/samples/bpf/tracex6_user.c b/samples/bpf/tracex6_user.c
new file mode 100644
index 0000000..928f05e
--- /dev/null
+++ b/samples/bpf/tracex6_user.c
@@ -0,0 +1,68 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sys/ioctl.h>
+#include <linux/perf_event.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+
+#define SAMPLE_PERIOD 0x7fffffffffffffffULL
+
+static void test_bpf_perf_event(void)
+{
+ int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+ int *pmu_fd = malloc(nr_cpus * sizeof(int));
+ unsigned long value;
+ int i;
+
+ struct perf_event_attr attr_insn_pmu = {
+ .freq = 0,
+ .sample_period = SAMPLE_PERIOD,
+ .inherit = 0,
+ .type = PERF_TYPE_HARDWARE,
+ .read_format = 0,
+ .sample_type = 0,
+ .config = 0,/* PMU: cycles */
+ };
+
+ for (i = 0; i < nr_cpus; i++) {
+ pmu_fd[i] = perf_event_open(&attr_insn_pmu, -1/*pid*/, i/*cpu*/, -1/*group_fd*/, 0);
+ if (pmu_fd[i] < 0)
+ printf("event syscall failed\n");
+
+ bpf_update_elem(map_fd[0], &i, &pmu_fd[i], BPF_ANY);
+ ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0);
+ }
+
+ system("ls");
+ system("pwd");
+ system("sleep 2");
+
+ for (i = 0; i < nr_cpus; i++)
+ close(pmu_fd[i]);
+
+ close(map_fd);
+
+ free(pmu_fd);
+}
+
+int main(int argc, char **argv)
+{
+ char filename[256];
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ test_bpf_perf_event();
+
+ return 0;
+}
--
1.8.3.4
--
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