Commit e3edfdec authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

samples/bpf: add tracepoint vs kprobe performance tests



the first microbenchmark does
fd=open("/proc/self/comm");
for() {
  write(fd, "test");
}
and on 4 cpus in parallel:
                                      writes per sec
base (no tracepoints, no kprobes)         930k
with kprobe at __set_task_comm()          420k
with tracepoint at task:task_rename       730k

For kprobe + full bpf program manully fetches oldcomm, newcomm via bpf_probe_read.
For tracepint bpf program does nothing, since arguments are copied by tracepoint.

2nd microbenchmark does:
fd=open("/dev/urandom");
for() {
  read(fd, buf);
}
and on 4 cpus in parallel:
                                       reads per sec
base (no tracepoints, no kprobes)         300k
with kprobe at urandom_read()             279k
with tracepoint at random:urandom_read    290k

bpf progs attached to kprobe and tracepoint are noop.
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3c9b1644
......@@ -19,6 +19,7 @@ hostprogs-y += lathist
hostprogs-y += offwaketime
hostprogs-y += spintest
hostprogs-y += map_perf_test
hostprogs-y += test_overhead
test_verifier-objs := test_verifier.o libbpf.o
test_maps-objs := test_maps.o libbpf.o
......@@ -38,6 +39,7 @@ lathist-objs := bpf_load.o libbpf.o lathist_user.o
offwaketime-objs := bpf_load.o libbpf.o offwaketime_user.o
spintest-objs := bpf_load.o libbpf.o spintest_user.o
map_perf_test-objs := bpf_load.o libbpf.o map_perf_test_user.o
test_overhead-objs := bpf_load.o libbpf.o test_overhead_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
......@@ -56,6 +58,8 @@ always += lathist_kern.o
always += offwaketime_kern.o
always += spintest_kern.o
always += map_perf_test_kern.o
always += test_overhead_tp_kern.o
always += test_overhead_kprobe_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
......@@ -75,6 +79,7 @@ HOSTLOADLIBES_lathist += -lelf
HOSTLOADLIBES_offwaketime += -lelf
HOSTLOADLIBES_spintest += -lelf
HOSTLOADLIBES_map_perf_test += -lelf -lrt
HOSTLOADLIBES_test_overhead += -lelf -lrt
# point this to your LLVM backend with bpf support
LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc
......
/* Copyright (c) 2016 Facebook
*
* 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_helpers.h"
#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;})
SEC("kprobe/__set_task_comm")
int prog(struct pt_regs *ctx)
{
struct signal_struct *signal;
struct task_struct *tsk;
char oldcomm[16] = {};
char newcomm[16] = {};
u16 oom_score_adj;
u32 pid;
tsk = (void *)PT_REGS_PARM1(ctx);
pid = _(tsk->pid);
bpf_probe_read(oldcomm, sizeof(oldcomm), &tsk->comm);
bpf_probe_read(newcomm, sizeof(newcomm), (void *)PT_REGS_PARM2(ctx));
signal = _(tsk->signal);
oom_score_adj = _(signal->oom_score_adj);
return 0;
}
SEC("kprobe/urandom_read")
int prog2(struct pt_regs *ctx)
{
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
/* Copyright (c) 2016 Facebook
*
* 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 <uapi/linux/bpf.h>
#include "bpf_helpers.h"
/* from /sys/kernel/debug/tracing/events/task/task_rename/format */
struct task_rename {
__u64 pad;
__u32 pid;
char oldcomm[16];
char newcomm[16];
__u16 oom_score_adj;
};
SEC("tracepoint/task/task_rename")
int prog(struct task_rename *ctx)
{
return 0;
}
/* from /sys/kernel/debug/tracing/events/random/urandom_read/format */
struct urandom_read {
__u64 pad;
int got_bits;
int pool_left;
int input_left;
};
SEC("tracepoint/random/urandom_read")
int prog2(struct urandom_read *ctx)
{
return 0;
}
char _license[] SEC("license") = "GPL";
/* Copyright (c) 2016 Facebook
*
* 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.
*/
#define _GNU_SOURCE
#include <sched.h>
#include <stdio.h>
#include <sys/types.h>
#include <asm/unistd.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/bpf.h>
#include <string.h>
#include <time.h>
#include <sys/resource.h>
#include "libbpf.h"
#include "bpf_load.h"
#define MAX_CNT 1000000
static __u64 time_get_ns(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ts.tv_sec * 1000000000ull + ts.tv_nsec;
}
static void test_task_rename(int cpu)
{
__u64 start_time;
char buf[] = "test\n";
int i, fd;
fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
if (fd < 0) {
printf("couldn't open /proc\n");
exit(1);
}
start_time = time_get_ns();
for (i = 0; i < MAX_CNT; i++)
write(fd, buf, sizeof(buf));
printf("task_rename:%d: %lld events per sec\n",
cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
close(fd);
}
static void test_urandom_read(int cpu)
{
__u64 start_time;
char buf[4];
int i, fd;
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0) {
printf("couldn't open /dev/urandom\n");
exit(1);
}
start_time = time_get_ns();
for (i = 0; i < MAX_CNT; i++)
read(fd, buf, sizeof(buf));
printf("urandom_read:%d: %lld events per sec\n",
cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
close(fd);
}
static void loop(int cpu, int flags)
{
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(cpu, &cpuset);
sched_setaffinity(0, sizeof(cpuset), &cpuset);
if (flags & 1)
test_task_rename(cpu);
if (flags & 2)
test_urandom_read(cpu);
}
static void run_perf_test(int tasks, int flags)
{
pid_t pid[tasks];
int i;
for (i = 0; i < tasks; i++) {
pid[i] = fork();
if (pid[i] == 0) {
loop(i, flags);
exit(0);
} else if (pid[i] == -1) {
printf("couldn't spawn #%d process\n", i);
exit(1);
}
}
for (i = 0; i < tasks; i++) {
int status;
assert(waitpid(pid[i], &status, 0) == pid[i]);
assert(status == 0);
}
}
static void unload_progs(void)
{
close(prog_fd[0]);
close(prog_fd[1]);
close(event_fd[0]);
close(event_fd[1]);
}
int main(int argc, char **argv)
{
struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
char filename[256];
int num_cpu = 8;
int test_flags = ~0;
setrlimit(RLIMIT_MEMLOCK, &r);
if (argc > 1)
test_flags = atoi(argv[1]) ? : test_flags;
if (argc > 2)
num_cpu = atoi(argv[2]) ? : num_cpu;
if (test_flags & 0x3) {
printf("BASE\n");
run_perf_test(num_cpu, test_flags);
}
if (test_flags & 0xC) {
snprintf(filename, sizeof(filename),
"%s_kprobe_kern.o", argv[0]);
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
printf("w/KPROBE\n");
run_perf_test(num_cpu, test_flags >> 2);
unload_progs();
}
if (test_flags & 0x30) {
snprintf(filename, sizeof(filename),
"%s_tp_kern.o", argv[0]);
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
printf("w/TRACEPOINT\n");
run_perf_test(num_cpu, test_flags >> 4);
unload_progs();
}
return 0;
}
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