Messages in this thread | | | Date | Tue, 31 Jul 2018 10:20:42 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2] perf build: Fix installation directory for bpf |
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Em Tue, Jul 31, 2018 at 09:32:54AM +0200, Thomas Richter escreveu: > Output after using command ./perf test -Fv 40: > echo '...[bpf-program-source]...' | /usr/bin/clang ... \ > -I/root/lib/perf/include/bpf ... > ^^^^^^^^^^^^ > ... > [root@p23lp27 perf]# ./perf test -F 40 > 40: BPF filter : > 40.1: Basic BPF filtering : Ok > 40.2: BPF pinning : Ok > 40.3: BPF prologue generation : Ok > 40.4: BPF relocation checker : Ok > [root@p23lp27 perf]#
So, testing it:
[root@jouet perf]# cat tools/perf/examples/bpf/5sec.c // SPDX-License-Identifier: GPL-2.0 /* Description:
. Disable strace like syscall tracing (--no-syscalls), or try tracing just some (-e *sleep).
. Attach a filter function to a kernel function, returning when it should be considered, i.e. appear on the output.
. Run it system wide, so that any sleep of >= 5 seconds and < than 6 seconds gets caught.
. Ask for callgraphs using DWARF info, so that userspace can be unwound
. While this is running, run something like "sleep 5s".
. If we decide to add tv_nsec as well, then it becomes:
int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
I.e. add where it comes from (rqtp->tv_nsec) and where it will be accessible in the function body (nsec)
# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/ 0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5 hrtimer_nanosleep ([kernel.kallsyms]) __x64_sys_nanosleep ([kernel.kallsyms]) do_syscall_64 ([kernel.kallsyms]) entry_SYSCALL_64 ([kernel.kallsyms]) __GI___nanosleep (/usr/lib64/libc-2.26.so) rpl_nanosleep (/usr/bin/sleep) xnanosleep (/usr/bin/sleep) main (/usr/bin/sleep) __libc_start_main (/usr/lib64/libc-2.26.so) _start (/usr/bin/sleep) ^C#
Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com> */
#include <bpf.h>
int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec) { return sec == 5; }
license(GPL); [root@jouet perf]# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c 0.000 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9911efe0) tv_sec=5 3145.238 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9911efe0) tv_sec=5 ^C[root@jouet perf]#
After it works just the same, thanks, applying.
I need to get the above testing process hooked up in 'perf test', so that besides adding that -I/root/lib/perf/include/bpf we actually _try_ to include something from there from the /root/lib/perf/examples/bpf/ bpf example scripts.
- Arnaldo
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