[PATCH 16/23] perf script: Support -F brstack,dso and brstacksym,dso

Arnaldo Carvalho de Melo
2017-06-20T01:58:05Z

From: Mark Santaniello <marksan@fb.com>

Perf script can report the dso for "addr" and "ip" fields.

This adds the same support for the "brstack" and "brstacksym" fields.
This can be helpful for AutoFDO: we can ignore LBR entries unless the
source and target address are both in the target module we are about to
build.

I built a small test akin to "while(1) { do_nothing(); }" where the
do_nothing function is loaded from a dso:

$ cat burncpu.cpp
#include <dlfcn.h>

int main() {
void* handle = dlopen("./dso.so", RTLD_LAZY);
if (!handle) return -1;

typedef void (*fp)();
fp do_nothing = (fp) dlsym(handle, "do_nothing");

while(1) {
do_nothing();
}
}

$ cat dso.cpp
extern "C" void do_nothing() {}

$ cat build.sh
#!/bin/bash
g++ -shared dso.cpp -o dso.so
g++ burncpu.cpp -o burncpu -ldl

I sampled the execution with perf record -b. Using the new perf script
functionality I can easily find cases where there was a transition from one
dso to another:

$ perf record -a -b -- sleep 5
[ perf record: Woken up 55 times to write data ]
[ perf record: Captured and wrote 18.815 MB perf.data (43593 samples) ]

$ perf script -F brstack,dso | sed 's/\/0 /\/0\n/g' | grep burncpu | grep dso.so | head -n 1
0x7f967139b6aa(/tmp/burncpu/dso.so)/0x4006b1(/tmp/burncpu/exe)/P/-/-/0

$ perf script -F brstacksym,dso | sed 's/\/0 /\/0\n/g' | grep burncpu | grep dso.so | head -n 1
do_nothing+0x5(/tmp/burncpu/dso.so)/main+0x44(/tmp/burncpu/exe)/P/-/-/0

Signed-off-by: Mark Santaniello <marksan@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170619163825.2012979-1-marksan@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 61 ++++++++++++++++++++++++++++++++++++---------
1 file changed, 49 insertions(+), 12 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index afa84debc5c4..3c21089f5273 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -298,10 +298,11 @@ static int perf_evsel__check_attr(struct perf_evsel *evsel,
"selected.\n");
return -EINVAL;
}
- if (PRINT_FIELD(DSO) && !PRINT_FIELD(IP) && !PRINT_FIELD(ADDR)) {
- pr_err("Display of DSO requested but neither sample IP nor "
- "sample address\nis selected. Hence, no addresses to convert "
- "to DSO.\n");
+ if (PRINT_FIELD(DSO) && !PRINT_FIELD(IP) && !PRINT_FIELD(ADDR) &&
+ !PRINT_FIELD(BRSTACK) && !PRINT_FIELD(BRSTACKSYM)) {
+ pr_err("Display of DSO requested but none of sample IP, sample address, "
+ "brstack\nor brstacksym are selected. Hence, no addresses to "
+ "convert to DSO.\n");
return -EINVAL;
}
if (PRINT_FIELD(SRCLINE) && !PRINT_FIELD(IP)) {
@@ -514,18 +515,43 @@ mispred_str(struct branch_entry *br)
return br->flags.predicted ? 'P' : 'M';
}

-static void print_sample_brstack(struct perf_sample *sample)
+static void print_sample_brstack(struct perf_sample *sample,
+ struct thread *thread,
+ struct perf_event_attr *attr)
{
struct branch_stack *br = sample->branch_stack;
- u64 i;
+ struct addr_location alf, alt;
+ u64 i, from, to;

if (!(br && br->nr))
return;

for (i = 0; i < br->nr; i++) {
- printf(" 0x%"PRIx64"/0x%"PRIx64"/%c/%c/%c/%d ",
- br->entries[i].from,
- br->entries[i].to,
+ from = br->entries[i].from;
+ to = br->entries[i].to;
+
+ if (PRINT_FIELD(DSO)) {
+ memset(&alf, 0, sizeof(alf));
+ memset(&alt, 0, sizeof(alt));
+ thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, from, &alf);
+ thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, to, &alt);
+ }
+
+ printf("0x%"PRIx64, from);
+ if (PRINT_FIELD(DSO)) {
+ printf("(");
+ map__fprintf_dsoname(alf.map, stdout);
+ printf(")");
+ }
+
+ printf("/0x%"PRIx64, to);
+ if (PRINT_FIELD(DSO)) {
+ printf("(");
+ map__fprintf_dsoname(alt.map, stdout);
+ printf(")");
+ }
+
+ printf("/%c/%c/%c/%d ",
mispred_str( br->entries + i),
br->entries[i].flags.in_tx? 'X' : '-',
br->entries[i].flags.abort? 'A' : '-',
@@ -534,7 +560,8 @@ static void print_sample_brstack(struct perf_sample *sample)
}

static void print_sample_brstacksym(struct perf_sample *sample,
- struct thread *thread)
+ struct thread *thread,
+ struct perf_event_attr *attr)
{
struct branch_stack *br = sample->branch_stack;
struct addr_location alf, alt;
@@ -559,8 +586,18 @@ static void print_sample_brstacksym(struct perf_sample *sample,
alt.sym = map__find_symbol(alt.map, alt.addr);

symbol__fprintf_symname_offs(alf.sym, &alf, stdout);
+ if (PRINT_FIELD(DSO)) {
+ printf("(");
+ map__fprintf_dsoname(alf.map, stdout);
+ printf(")");
+ }
putchar('/');
symbol__fprintf_symname_offs(alt.sym, &alt, stdout);
+ if (PRINT_FIELD(DSO)) {
+ printf("(");
+ map__fprintf_dsoname(alt.map, stdout);
+ printf(")");
+ }
printf("/%c/%c/%c/%d ",
mispred_str( br->entries + i),
br->entries[i].flags.in_tx? 'X' : '-',
@@ -1187,9 +1224,9 @@ static void process_event(struct perf_script *script,
print_sample_iregs(sample, attr);

if (PRINT_FIELD(BRSTACK))
- print_sample_brstack(sample);
+ print_sample_brstack(sample, thread, attr);
else if (PRINT_FIELD(BRSTACKSYM))
- print_sample_brstacksym(sample, thread);
+ print_sample_brstacksym(sample, thread, attr);

if (perf_evsel__is_bpf_output(evsel) && PRINT_FIELD(BPF_OUTPUT))
print_sample_bpf_output(sample);
--
2.9.4