linux-toradex.git/tools/perf/util/target.c, branch v6.3

perf stat: Enable counting events for BPF programs

2021-01-20T17:25:28+00:00

Introduce 'perf stat -b' option, which counts events for BPF programs, like:

  [root@localhost ~]# ~/perf stat -e ref-cycles,cycles -b 254 -I 1000
     1.487903822            115,200      ref-cycles
     1.487903822             86,012      cycles
     2.489147029             80,560      ref-cycles
     2.489147029             73,784      cycles
     3.490341825             60,720      ref-cycles
     3.490341825             37,797      cycles
     4.491540887             37,120      ref-cycles
     4.491540887             31,963      cycles

The example above counts 'cycles' and 'ref-cycles' of BPF program of id
254.  This is similar to bpftool-prog-profile command, but more
flexible.

'perf stat -b' creates per-cpu perf_event and loads fentry/fexit BPF
programs (monitor-progs) to the target BPF program (target-prog). The
monitor-progs read perf_event before and after the target-prog, and
aggregate the difference in a BPF map. Then the user space reads data
from these maps.

A new 'struct bpf_counter' is introduced to provide a common interface
that uses BPF programs/maps to count perf events.

Committer notes:

Removed all but bpf_counter.h includes from evsel.h, not needed at all.

Also BPF map lookups for PERCPU_ARRAYs need to have as its value receive
buffer passed to the kernel libbpf_num_possible_cpus() entries, not
evsel__nr_cpus(evsel), as the former uses
/sys/devices/system/cpu/possible while the later uses
/sys/devices/system/cpu/online, which may be less than the 'possible'
number making the bpf map lookup overwrite memory and cause hard to
debug memory corruption.

We need to continue using evsel__nr_cpus(evsel) when accessing the
perf_counts array tho, not to overwrite another are of memory :-)

Signed-off-by: Song Liu 
Tested-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/lkml/20210120163031.GU12699@kernel.org/
Acked-by: Namhyung Kim 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Peter Zijlstra 
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20201229214214.3413833-4-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove util.h from where it is not needed

2019-09-20T12:19:20+00:00

Check that it is not needed and remove, fixing up some fallout for
places where it was only serving to get something else.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-9h6dg6lsqe2usyqjh5rrues4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove debug.h from places where it is not needed

2019-09-20T12:19:20+00:00

Pruning a bit more the includes dependency tree. Building this thing on
lots of containers takes time, we better reduce the time per build, each
container is doing 6 builds when clang and clang-devel are available,
and the plan is to do a 'make -C tools/perf build-test' that have many
more.

Also helps when doing normal development, as touching some random file
will have a much reduced chance of triggering lots of rebuilds.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-r889ur2cxe16m91m2a4pl15p@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf debug: Remove needless include directives from debug.h

2019-08-31T22:10:19+00:00

All we need there is a forward declaration for 'union perf_event', so
remove it from there and add missing header directives in places using
things from this indirect include.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-7ftk0ztstqub1tirjj8o8xbl@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add missing headers, mostly stdlib.h

2019-07-09T13:13:22+00:00

Part of the erosion of util/util.h, that will lose its include stdlib.h,
we need to add it to places where it is needed but was getting it
indirectly.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-1imnqezw99ahc07fjeb51qby@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 433

2019-06-05T15:37:16+00:00

Based on 1 normalized pattern(s):

  released under the gpl v2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 2 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Armijn Hemel 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190114.749096322@linutronix.de
Signed-off-by: Greg Kroah-Hartman

perf target: str_error_r() always returns the buffer it receives

2016-07-29T14:54:35+00:00

So no need for checking if it uses the strerror_r() GNU variant error
reporting mechanism, i.e. if it returns a pointer to a immutable string
internal to glibc.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Fixes: c8b5f2c96d1b ("tools: Introduce str_error_r()")
Link: http://lkml.kernel.org/n/tip-xr83cd4y4r3cn6tq6w4f59jb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove needless includes from cache.h

2016-07-12T18:19:58+00:00

The cache.h header doesn't use any of the definitions in some of the
headers it includes, ditch them and fix the fallout, where files were
getting stuff they needed just because they were including it, sometimes
not using what it really exports at all.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-l6r2bmj8h1g3e01wr981on0n@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools: Introduce str_error_r()

2016-07-12T18:19:47+00:00

The tools so far have been using the strerror_r() GNU variant, that
returns a string, be it the buffer passed or something else.

But that, besides being tricky in cases where we expect that the
function using strerror_r() returns the error formatted in a provided
buffer (we have to check if it returned something else and copy that
instead), breaks the build on systems not using glibc, like Alpine
Linux, where musl libc is used.

So, introduce yet another wrapper, str_error_r(), that has the GNU
interface, but uses the portable XSI variant of strerror_r(), so that
users rest asured that the provided buffer is used and it is what is
returned.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-d4t42fnf48ytlk8rjxs822tf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf target: Simplify handling of strerror_r return

2015-03-24T15:08:30+00:00

To deal with forwarding the strerror_r (GNU) return we need to check if
the returned value is the buffer we passed or maybe some constant
(unknown error), simplify that action by using scnprintf, that will do
all the buflen size checks, trimming if needed.

Acked-by: Jiri Olsa 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Don Zickus 
Cc: Frederic Weisbecker 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-d0ik6i5gjew56j0qphql28ou@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo