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e3edfdec04
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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
36 lines
828 B
C
36 lines
828 B
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 <uapi/linux/bpf.h>
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#include "bpf_helpers.h"
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/* from /sys/kernel/debug/tracing/events/task/task_rename/format */
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struct task_rename {
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__u64 pad;
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__u32 pid;
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char oldcomm[16];
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char newcomm[16];
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__u16 oom_score_adj;
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};
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SEC("tracepoint/task/task_rename")
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int prog(struct task_rename *ctx)
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{
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return 0;
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}
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/* from /sys/kernel/debug/tracing/events/random/urandom_read/format */
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struct urandom_read {
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__u64 pad;
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int got_bits;
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int pool_left;
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int input_left;
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};
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SEC("tracepoint/random/urandom_read")
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int prog2(struct urandom_read *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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