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Arnaldo Carvalho de Melo 7542b767b0 perf bpf: Add kprobe example to catch 5s naps
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:

  $ cat tools/perf/examples/bpf/5sec.c
  #include <bpf.h>

  SEC("func=hrtimer_nanosleep rqtp->tv_sec")
  int func(void *ctx, int err, long sec)
  {
	  return sec == 5;
  }

  char _license[] SEC("license") = "GPL";
  int _version SEC("version") = LINUX_VERSION_CODE;
  $

. 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".

  # 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#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-2nmxth2l2h09f9gy85lyexcq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-05-15 14:31:24 -03:00
arch Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:53:08 -07:00
block blk-mq: fix sysfs inflight counter 2018-04-26 09:02:01 -06:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto crypto: drbg - set freed buffers to NULL 2018-04-21 00:57:00 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
drivers Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2018-05-12 10:58:57 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs some small SMB3 fixes for 4.17-rc5, some for stable 2018-05-12 18:49:53 -07:00
include Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:53:08 -07:00
init init: fix false positives in W+X checking 2018-05-11 17:28:45 -07:00
ipc ipc/shm: fix use-after-free of shm file via remap_file_pages() 2018-04-13 17:10:27 -07:00
kernel Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:53:08 -07:00
lib another dma-mapping fix for 4.17-rc: 2018-05-13 10:28:53 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
samples bpf: sockmap sample use clang flag, -target bpf 2018-04-23 23:42:21 +02:00
scripts scripts/faddr2line: fix error when addr2line output contains discriminator 2018-05-11 17:28:45 -07:00
security Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-24 17:58:51 -07:00
sound ALSA: pcm: Check PCM state at xfern compat ioctl 2018-05-02 08:54:54 +02:00
tools perf bpf: Add kprobe example to catch 5s naps 2018-05-15 14:31:24 -03:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM/arm fixes for 4.17, take #2 2018-05-05 23:05:31 +02:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge candidates for 4.17 merge window 2018-04-06 17:35:43 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
Makefile Linux 4.17-rc5 2018-05-13 16:15:17 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.