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Date: Mon, 27 Jun 2022 17:45:29 +0100
From: German Gomez <german.gomez@....com>
To: Ian Rogers <irogers@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
acme@...nel.org, Anshuman Khandual <anshuman.khandual@....com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] perf test: Add test for branch stack sampling
On 27/06/2022 17:38, Ian Rogers wrote:
> On Wed, Jun 15, 2022 at 6:09 AM German Gomez <german.gomez@....com> wrote:
>> Add a self test for branch stack sampling, to check that we get the
>> expected branch types, and filters behave as expected.
>>
>> Suggested-by: Anshuman Khandual <anshuman.khandual@....com>
>> Signed-off-by: German Gomez <german.gomez@....com>
> Love tests, thanks! There are already shell tests that compile C code
> but they do it by having the C code within the shell test, for
> example:
> https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/tests/shell/pipe_test.sh?h=perf/core#n14
> Having it this way I thinks means the tests can run properly when
> installed, as we don't install non-sh files:
> https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/Makefile.perf?h=perf/core#n1016
Ah! thanks for pointing this out, Ian. I've embedded C code within shell tests before, but I wasn't aware of the install issue.
We'll take care of this, thanks for the review!
>
> Thanks,
> Ian
>
>> ---
>> tools/perf/tests/shell/lib/brstack/main.h | 16 +++++
>> tools/perf/tests/shell/lib/brstack/test.c | 24 +++++++
>> tools/perf/tests/shell/test_brstack.sh | 86 +++++++++++++++++++++++
>> 3 files changed, 126 insertions(+)
>> create mode 100644 tools/perf/tests/shell/lib/brstack/main.h
>> create mode 100644 tools/perf/tests/shell/lib/brstack/test.c
>> create mode 100755 tools/perf/tests/shell/test_brstack.sh
>>
>> diff --git a/tools/perf/tests/shell/lib/brstack/main.h b/tools/perf/tests/shell/lib/brstack/main.h
>> new file mode 100644
>> index 000000000..94d2665ec
>> --- /dev/null
>> +++ b/tools/perf/tests/shell/lib/brstack/main.h
>> @@ -0,0 +1,16 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +#define BENCH_RUNS 99999
>> +
>> +void bench(void);
>> +
>> +int main(void)
>> +{
>> + int cnt = 0;
>> +
>> + while (1) {
>> + if ((cnt++) > BENCH_RUNS)
>> + break;
>> + bench(); /* call */
>> + } /* branch (uncond) */
>> + return 0;
>> +}
>> diff --git a/tools/perf/tests/shell/lib/brstack/test.c b/tools/perf/tests/shell/lib/brstack/test.c
>> new file mode 100644
>> index 000000000..8a2308901
>> --- /dev/null
>> +++ b/tools/perf/tests/shell/lib/brstack/test.c
>> @@ -0,0 +1,24 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +#include "main.h"
>> +
>> +int cnt;
>> +
>> +void bar(void)
>> +{
>> +} /* return */
>> +
>> +void foo(void)
>> +{
>> + bar(); /* call */
>> +} /* return */
>> +
>> +void bench(void)
>> +{
>> + void (*foo_ind)(void) = foo;
>> +
>> + if ((cnt++) % 3) /* branch (cond) */
>> + foo(); /* call */
>> +
>> + bar(); /* call */
>> + foo_ind(); /* call (ind) */
>> +}
>> diff --git a/tools/perf/tests/shell/test_brstack.sh b/tools/perf/tests/shell/test_brstack.sh
>> new file mode 100755
>> index 000000000..2b1a1b20a
>> --- /dev/null
>> +++ b/tools/perf/tests/shell/test_brstack.sh
>> @@ -0,0 +1,86 @@
>> +#!/bin/sh
>> +# Check branch stack sampling
>> +
>> +# SPDX-License-Identifier: GPL-2.0
>> +# German Gomez <german.gomez@....com>, 2022
>> +
>> +set -e
>> +
>> +# we need a C compiler to build the test programs
>> +# so bail if none is found
>> +if ! [ -x "$(command -v cc)" ]; then
>> + echo "failed: no compiler, install gcc"
>> + exit 2
>> +fi
>> +
>> +# skip the test if the hardware doesn't support branch stack sampling
>> +perf record -b -o- -- true > /dev/null || exit 2
>> +
>> +TMPDIR=$(mktemp -d /tmp/__perf_test.program.XXXXX)
>> +
>> +cleanup() {
>> + rm -rf $TMPDIR
>> +}
>> +
>> +trap cleanup exit term int
>> +
>> +test_user_branches() {
>> + echo
>> + echo "Testing user branch stack sampling"
>> + echo
>> +
>> + cc -fno-inline -g "$(dirname $0)/lib/brstack/test.c" -o $TMPDIR/a.out
>> +
>> + perf record -o $TMPDIR/perf.data -q --branch-filter any,save_type,u -- $TMPDIR/a.out
>> + perf script -i $TMPDIR/perf.data --fields brstacksym | xargs -n1 > $TMPDIR/perf.script
>> +
>> + # example of branch entries:
>> + # foo+0x14/bar+0x40/P/-/-/0/CALL
>> +
>> + set -x
>> + egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/IND_CALL$" $TMPDIR/perf.script
>> + egrep -m1 "^foo\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
>> + egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/CALL$" $TMPDIR/perf.script
>> + egrep -m1 "^bench\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
>> + egrep -m1 "^bar\+[^ ]*/foo\+[^ ]*/RET$" $TMPDIR/perf.script
>> + egrep -m1 "^foo\+[^ ]*/bench\+[^ ]*/RET$" $TMPDIR/perf.script
>> + egrep -m1 "^bench\+[^ ]*/bench\+[^ ]*/COND$" $TMPDIR/perf.script
>> + egrep -m1 "^main\+[^ ]*/main\+[^ ]*/UNCOND$" $TMPDIR/perf.script
>> + set +x
>> +
>> + # some branch types are still not being tested:
>> + # IND COND_CALL COND_RET SYSCALL SYSRET IRQ SERROR NO_TX
>> +}
>> +
>> +test_filter() {
>> + local filter=$1
>> + local expect=$2
>> +
>> + echo
>> + echo "Testing branch stack filtering permutation ($filter,$expect)"
>> + echo
>> +
>> + cc -fno-inline -g "$(dirname $0)/lib/brstack/test.c" -o $TMPDIR/a.out
>> +
>> + perf record -o $TMPDIR/perf.data -q --branch-filter $filter,save_type,u -- $TMPDIR/a.out
>> + perf script -i $TMPDIR/perf.data --fields brstack | xargs -n1 > $TMPDIR/perf.script
>> +
>> + # fail if we find any branch type that doesn't match any of the expected ones
>> + # also consider UNKNOWN branch types (-)
>> + if egrep -vm1 "^[^ ]*/($expect|-|( *))$" $TMPDIR/perf.script; then
>> + return 1
>> + fi
>> +}
>> +
>> +test_user_branches
>> +
>> +# first argument <arg0> is the argument passed to "--branch-stack <arg0>,save_type,u"
>> +# second argument are the expected branch types for the given filter
>> +test_filter "any_call" "CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|FAULT_DATA|FAULT_INST"
>> +test_filter "call" "CALL|SYSCALL"
>> +test_filter "cond" "COND"
>> +test_filter "any_ret" "RET|COND_RET|SYSRET|ERET"
>> +
>> +test_filter "call,cond" "CALL|SYSCALL|COND"
>> +test_filter "any_call,cond" "CALL|IND_CALL|COND_CALL|IRQ|FAULT_DATA|FAULT_INST|SYSCALL|COND"
>> +test_filter "cond,any_call,any_ret" "COND|CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|FAULT_DATA|FAULT_INST|RET|COND_RET|SYSRET|ERET"
>> --
>> 2.25.1
>>
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