From c4781e37c6a22c39cb4a57411d14f42aca124f04 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 21 Nov 2019 17:15:15 -0800 Subject: selftests/bpf: Add BPF trampoline performance test Add a test that benchmarks different ways of attaching BPF program to a kernel function. Here are the results for 2.4Ghz x86 cpu on a kernel without mitigations: $ ./test_progs -n 49 -v|grep events task_rename base 2743K events per sec task_rename kprobe 2419K events per sec task_rename kretprobe 1876K events per sec task_rename raw_tp 2578K events per sec task_rename fentry 2710K events per sec task_rename fexit 2685K events per sec On a kernel with retpoline: $ ./test_progs -n 49 -v|grep events task_rename base 2401K events per sec task_rename kprobe 1930K events per sec task_rename kretprobe 1485K events per sec task_rename raw_tp 2053K events per sec task_rename fentry 2351K events per sec task_rename fexit 2185K events per sec All 5 approaches: - kprobe/kretprobe in __set_task_comm() - raw tracepoint in trace_task_rename() - fentry/fexit in __set_task_comm() are roughly equivalent. __set_task_comm() by itself is quite fast, so any extra instructions add up. Until BPF trampoline was introduced the fastest mechanism was raw tracepoint. kprobe via ftrace was second best. kretprobe is slow due to trap. New fentry/fexit methods via BPF trampoline are clearly the fastest and the difference is more pronounced with retpoline on, since BPF trampoline doesn't use indirect jumps. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20191122011515.255371-1-ast@kernel.org --- tools/testing/selftests/bpf/progs/test_overhead.c | 43 +++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/test_overhead.c (limited to 'tools/testing/selftests/bpf/progs/test_overhead.c') diff --git a/tools/testing/selftests/bpf/progs/test_overhead.c b/tools/testing/selftests/bpf/progs/test_overhead.c new file mode 100644 index 000000000000..ef06b2693f96 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_overhead.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ +#include +#include "bpf_helpers.h" +#include "bpf_tracing.h" + +SEC("kprobe/__set_task_comm") +int prog1(struct pt_regs *ctx) +{ + return 0; +} + +SEC("kretprobe/__set_task_comm") +int prog2(struct pt_regs *ctx) +{ + return 0; +} + +SEC("raw_tp/task_rename") +int prog3(struct bpf_raw_tracepoint_args *ctx) +{ + return 0; +} + +struct __set_task_comm_args { + struct task_struct *tsk; + const char *buf; + ku8 exec; +}; + +SEC("fentry/__set_task_comm") +int prog4(struct __set_task_comm_args *ctx) +{ + return 0; +} + +SEC("fexit/__set_task_comm") +int prog5(struct __set_task_comm_args *ctx) +{ + return 0; +} + +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3-59-g8ed1b