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It was looking at bpf/bpf.h, which caused this problem:
# perf trace -e tools/perf/examples/bpf/5sec.c
/home/acme/git/perf/tools/perf/examples/bpf/5sec.c:42:10: fatal error: 'bpf/bpf.h' file not found
#include <bpf/bpf.h>
^~~~~~~~~~~
1 error generated.
ERROR: unable to compile tools/perf/examples/bpf/5sec.c
Hint: Check error message shown above.
Hint: You can also pre-compile it into .o using:
clang -target bpf -O2 -c tools/perf/examples/bpf/5sec.c
with proper -I and -D options.
event syntax error: 'tools/perf/examples/bpf/5sec.c'
\___ Failed to load tools/perf/examples/bpf/5sec.c from source: Error when compiling BPF scriptlet
#
Change that to plain bpf.h, to make it work again:
# perf trace -e tools/perf/examples/bpf/5sec.c sleep 5s
0.000 perf_bpf_probe:hrtimer_nanosleep(__probe_ip: -1776891872, rqtp: 5000000000)
# perf trace -e tools/perf/examples/bpf/5sec.c/max-stack=16/ sleep 5s
0.000 perf_bpf_probe:hrtimer_nanosleep(__probe_ip: -1776891872, rqtp: 5000000000)
hrtimer_nanosleep ([kernel.kallsyms])
common_nsleep ([kernel.kallsyms])
__x64_sys_clock_nanosleep ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
__clock_nanosleep_2 (/usr/lib64/libc-2.32.so)
# perf trace -e tools/perf/examples/bpf/5sec.c sleep 4s
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
52 lines
2.0 KiB
C
52 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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Description:
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. Disable strace like syscall tracing (--no-syscalls), or try tracing
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just some (-e *sleep).
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. Attach a filter function to a kernel function, returning when it should
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be considered, i.e. appear on the output.
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. Run it system wide, so that any sleep of >= 5 seconds and < than 6
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seconds gets caught.
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. Ask for callgraphs using DWARF info, so that userspace can be unwound
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. While this is running, run something like "sleep 5s".
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. If we decide to add tv_nsec as well, then it becomes:
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int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
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I.e. add where it comes from (rqtp->tv_nsec) and where it will be
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accessible in the function body (nsec)
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# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
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0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
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hrtimer_nanosleep ([kernel.kallsyms])
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__x64_sys_nanosleep ([kernel.kallsyms])
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do_syscall_64 ([kernel.kallsyms])
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entry_SYSCALL_64 ([kernel.kallsyms])
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__GI___nanosleep (/usr/lib64/libc-2.26.so)
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rpl_nanosleep (/usr/bin/sleep)
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xnanosleep (/usr/bin/sleep)
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main (/usr/bin/sleep)
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__libc_start_main (/usr/lib64/libc-2.26.so)
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_start (/usr/bin/sleep)
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^C#
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Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com>
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*/
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#include <bpf.h>
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#define NSEC_PER_SEC 1000000000L
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int probe(hrtimer_nanosleep, rqtp)(void *ctx, int err, long long sec)
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{
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return sec / NSEC_PER_SEC == 5ULL;
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}
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license(GPL);
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