[PATCH 30/30] perf tools: Set the maximum allowed stack from /proc/sys/kernel/perf_event_max_stack

From: Arnaldo Carvalho de Melo
Date: Wed Apr 27 2016 - 10:38:48 EST

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From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

There is an upper limit to what tooling considers a valid callchain,
and it was tied to the hardcoded value in the kernel,
PERF_MAX_STACK_DEPTH (127), now that this can be tuned via a sysctl,
make it read it and use that as the upper limit, falling back to
PERF_MAX_STACK_DEPTH for kernels where this sysctl isn't present.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Milian Wolff <milian.wolff@xxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-yjqsd30nnkogvj5oyx9ghir9@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/Documentation/perf-report.txt | 2 +-
tools/perf/Documentation/perf-script.txt | 2 +-
tools/perf/Documentation/perf-top.txt | 2 +-
tools/perf/Documentation/perf-trace.txt | 2 +-
tools/perf/builtin-report.c | 4 ++--
tools/perf/builtin-script.c | 4 +++-
tools/perf/builtin-top.c | 4 ++--
tools/perf/builtin-trace.c | 4 ++--
tools/perf/perf.c | 5 +++++
tools/perf/tests/hists_cumulate.c | 2 +-
tools/perf/tests/hists_filter.c | 2 +-
tools/perf/tests/hists_output.c | 2 +-
tools/perf/util/machine.c | 6 +++---
tools/perf/util/scripting-engines/trace-event-perl.c | 2 +-
tools/perf/util/util.c | 2 ++
tools/perf/util/util.h | 1 +
16 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 496d42cdf02b..ebaf849e30ef 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -248,7 +248,7 @@ OPTIONS
Note that when using the --itrace option the synthesized callchain size
will override this value if the synthesized callchain size is bigger.

- Default: 127
+ Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.

-G::
--inverted::
diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 4fc44c75263f..a856a1095893 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -267,7 +267,7 @@ include::itrace.txt[]
Note that when using the --itrace option the synthesized callchain size
will override this value if the synthesized callchain size is bigger.

- Default: 127
+ Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.

--ns::
Use 9 decimal places when displaying time (i.e. show the nanoseconds)
diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index 19f046f027cd..91d638df3a6b 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -177,7 +177,7 @@ Default is to monitor all CPUS.
between information loss and faster processing especially for
workloads that can have a very long callchain stack.

- Default: 127
+ Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.

--ignore-callees=<regex>::
Ignore callees of the function(s) matching the given regex.
diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index c075c002eaa4..6afe20121bc0 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -143,7 +143,7 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs.
Implies '--call-graph dwarf' when --call-graph not present on the
command line, on systems where DWARF unwinding was built in.

- Default: 127
+ Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.

--min-stack::
Set the stack depth limit when parsing the callchain, anything
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 1d5be0bd426f..8d9b88af901d 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -691,7 +691,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
.ordered_events = true,
.ordering_requires_timestamps = true,
},
- .max_stack = PERF_MAX_STACK_DEPTH,
+ .max_stack = sysctl_perf_event_max_stack,
.pretty_printing_style = "normal",
.socket_filter = -1,
};
@@ -744,7 +744,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_INTEGER(0, "max-stack", &report.max_stack,
"Set the maximum stack depth when parsing the callchain, "
"anything beyond the specified depth will be ignored. "
- "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+ "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
OPT_BOOLEAN('G', "inverted", &report.inverted_callchain,
"alias for inverted call graph"),
OPT_CALLBACK(0, "ignore-callees", NULL, "regex",
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index f43b0c6f88f4..efca81679bb3 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2031,7 +2031,7 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_UINTEGER(0, "max-stack", &scripting_max_stack,
"Set the maximum stack depth when parsing the callchain, "
"anything beyond the specified depth will be ignored. "
- "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+ "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
OPT_BOOLEAN('I', "show-info", &show_full_info,
"display extended information from perf.data file"),
OPT_BOOLEAN('\0', "show-kernel-path", &symbol_conf.show_kernel_path,
@@ -2067,6 +2067,8 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
NULL
};

+ scripting_max_stack = sysctl_perf_event_max_stack;
+
setup_scripting();

argc = parse_options_subcommand(argc, argv, options, script_subcommands, script_usage,
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index c130a11d3a0d..da18517b1d40 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1103,7 +1103,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
},
.proc_map_timeout = 500,
},
- .max_stack = PERF_MAX_STACK_DEPTH,
+ .max_stack = sysctl_perf_event_max_stack,
.sym_pcnt_filter = 5,
};
struct record_opts *opts = &top.record_opts;
@@ -1171,7 +1171,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
"Accumulate callchains of children and show total overhead as well"),
OPT_INTEGER(0, "max-stack", &top.max_stack,
"Set the maximum stack depth when parsing the callchain. "
- "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+ "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
OPT_CALLBACK(0, "ignore-callees", NULL, "regex",
"ignore callees of these functions in call graphs",
report_parse_ignore_callees_opt),
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 48b00f042599..f4f3389c92c7 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -3106,7 +3106,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_UINTEGER(0, "max-stack", &trace.max_stack,
"Set the maximum stack depth when parsing the callchain, "
"anything beyond the specified depth will be ignored. "
- "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+ "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
OPT_UINTEGER(0, "proc-map-timeout", &trace.opts.proc_map_timeout,
"per thread proc mmap processing timeout in ms"),
OPT_END()
@@ -3150,7 +3150,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
mmap_pages_user_set = false;

if (trace.max_stack == UINT_MAX) {
- trace.max_stack = PERF_MAX_STACK_DEPTH;
+ trace.max_stack = sysctl_perf_event_max_stack;
max_stack_user_set = false;
}

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 7b2df2b46525..83ffe7cd7330 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -17,6 +17,7 @@
#include <subcmd/parse-options.h>
#include "util/bpf-loader.h"
#include "util/debug.h"
+#include <api/fs/fs.h>
#include <api/fs/tracing_path.h>
#include <pthread.h>
#include <stdlib.h>
@@ -533,6 +534,7 @@ int main(int argc, const char **argv)
{
const char *cmd;
char sbuf[STRERR_BUFSIZE];
+ int value;

/* libsubcmd init */
exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
@@ -542,6 +544,9 @@ int main(int argc, const char **argv)
page_size = sysconf(_SC_PAGE_SIZE);
cacheline_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);

+ if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
+ sysctl_perf_event_max_stack = value;
+
cmd = extract_argv0_path(argv[0]);
if (!cmd)
cmd = "perf-help";
diff --git a/tools/perf/tests/hists_cumulate.c b/tools/perf/tests/hists_cumulate.c
index ed5aa9eaeb6c..4a2bbff9b1ee 100644
--- a/tools/perf/tests/hists_cumulate.c
+++ b/tools/perf/tests/hists_cumulate.c
@@ -101,7 +101,7 @@ static int add_hist_entries(struct hists *hists, struct machine *machine)
if (machine__resolve(machine, &al, &sample) < 0)
goto out;

- if (hist_entry_iter__add(&iter, &al, PERF_MAX_STACK_DEPTH,
+ if (hist_entry_iter__add(&iter, &al, sysctl_perf_event_max_stack,
NULL) < 0) {
addr_location__put(&al);
goto out;
diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
index b825d24f8186..e846f8c42013 100644
--- a/tools/perf/tests/hists_filter.c
+++ b/tools/perf/tests/hists_filter.c
@@ -81,7 +81,7 @@ static int add_hist_entries(struct perf_evlist *evlist,

al.socket = fake_samples[i].socket;
if (hist_entry_iter__add(&iter, &al,
- PERF_MAX_STACK_DEPTH, NULL) < 0) {
+ sysctl_perf_event_max_stack, NULL) < 0) {
addr_location__put(&al);
goto out;
}
diff --git a/tools/perf/tests/hists_output.c b/tools/perf/tests/hists_output.c
index d3556fbe8c5c..7cd8738e842f 100644
--- a/tools/perf/tests/hists_output.c
+++ b/tools/perf/tests/hists_output.c
@@ -67,7 +67,7 @@ static int add_hist_entries(struct hists *hists, struct machine *machine)
if (machine__resolve(machine, &al, &sample) < 0)
goto out;

- if (hist_entry_iter__add(&iter, &al, PERF_MAX_STACK_DEPTH,
+ if (hist_entry_iter__add(&iter, &al, sysctl_perf_event_max_stack,
NULL) < 0) {
addr_location__put(&al);
goto out;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 656c1d7ee7d4..2cb95bbf9ea6 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1764,7 +1764,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
*/
int mix_chain_nr = i + 1 + lbr_nr + 1;

- if (mix_chain_nr > PERF_MAX_STACK_DEPTH + PERF_MAX_BRANCH_DEPTH) {
+ if (mix_chain_nr > (int)sysctl_perf_event_max_stack + PERF_MAX_BRANCH_DEPTH) {
pr_warning("corrupted callchain. skipping...\n");
return 0;
}
@@ -1825,7 +1825,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
* Based on DWARF debug information, some architectures skip
* a callchain entry saved by the kernel.
*/
- if (chain->nr < PERF_MAX_STACK_DEPTH)
+ if (chain->nr < sysctl_perf_event_max_stack)
skip_idx = arch_skip_callchain_idx(thread, chain);

/*
@@ -1886,7 +1886,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
}

check_calls:
- if (chain->nr > PERF_MAX_STACK_DEPTH && (int)chain->nr > max_stack) {
+ if (chain->nr > sysctl_perf_event_max_stack && (int)chain->nr > max_stack) {
pr_warning("corrupted callchain. skipping...\n");
return 0;
}
diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c b/tools/perf/util/scripting-engines/trace-event-perl.c
index ae1cebc307c5..62c7f6988e0e 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -265,7 +265,7 @@ static SV *perl_process_callchain(struct perf_sample *sample,

if (thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL,
- PERF_MAX_STACK_DEPTH) != 0) {
+ sysctl_perf_event_max_stack) != 0) {
pr_err("Failed to resolve callchain. Skipping\n");
goto exit;
}
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9473d46c00bb..619ba2061b62 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -33,6 +33,8 @@ struct callchain_param callchain_param = {
unsigned int page_size;
int cacheline_size;

+unsigned int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
+
bool test_attr__enabled;

bool perf_host = true;
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 26a924651e7b..88f607af1f47 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -267,6 +267,7 @@ void sighandler_dump_stack(int sig);

extern unsigned int page_size;
extern int cacheline_size;
+extern unsigned int sysctl_perf_event_max_stack;

struct parse_tag {
char tag;
--
2.5.5

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