perf tools: Set the maximum allowed stack from /proc/sys/kernel/perf_event_max_stack

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@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-yjqsd30nnkogvj5oyx9ghir9@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c5dfd78e
......@@ -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::
......
......@@ -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)
......
......@@ -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.
......
......@@ -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
......
......@@ -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",
......
......@@ -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,
......
......@@ -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),
......
......@@ -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;
}
......
......@@ -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";
......
......@@ -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;
......
......@@ -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;
}
......
......@@ -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;
......
......@@ -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;
}
......
......@@ -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;
}
......
......@@ -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;
......
......@@ -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;
......
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