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58e975d014
The test_overhead bpf program is designed to compare performance between tracepoint and kprobe. Initially it used task_rename and urandom_read tracepoint. However, commit14c174633f("random: remove unused tracepoints") removed urandom_read tracepoint, and for this reason the test_overhead got broken. This commit introduces new microbenchmark using fib_table_lookup. This microbenchmark sends UDP packets to localhost in order to invoke fib_table_lookup. In a nutshell: fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); addr.sin_addr.s_addr = inet_addr(DUMMY_IP); addr.sin_port = htons(DUMMY_PORT); for() { sendto(fd, buf, strlen(buf), 0, (struct sockaddr *)&addr, sizeof(addr)); } on 4 cpus in parallel: lookup per sec base (no tracepoints, no kprobes) 381k with kprobe at fib_table_lookup() 325k with tracepoint at fib:fib_table_lookup 330k with raw_tracepoint at fib:fib_table_lookup 365k Fixes:14c174633f("random: remove unused tracepoints") Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Link: https://lore.kernel.org/r/20230115071613.125791-6-danieltimlee@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/version.h>
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#include <linux/ptrace.h>
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#include <linux/sched.h>
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#include <uapi/linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#define _(P) \
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({ \
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typeof(P) val = 0; \
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bpf_probe_read_kernel(&val, sizeof(val), &(P)); \
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val; \
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})
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SEC("kprobe/__set_task_comm")
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int prog(struct pt_regs *ctx)
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{
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struct signal_struct *signal;
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struct task_struct *tsk;
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char oldcomm[TASK_COMM_LEN] = {};
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char newcomm[TASK_COMM_LEN] = {};
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u16 oom_score_adj;
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u32 pid;
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tsk = (void *)PT_REGS_PARM1(ctx);
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pid = _(tsk->pid);
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bpf_probe_read_kernel_str(oldcomm, sizeof(oldcomm), &tsk->comm);
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bpf_probe_read_kernel_str(newcomm, sizeof(newcomm),
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(void *)PT_REGS_PARM2(ctx));
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signal = _(tsk->signal);
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oom_score_adj = _(signal->oom_score_adj);
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return 0;
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}
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SEC("kprobe/fib_table_lookup")
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int prog2(struct pt_regs *ctx)
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{
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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