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Subject[PATCH -tip 4/4] perf probe: Add --max-probes option
Date
Add --max-probes option to change the maximum limit of
findable probe points per event, since inlined function can be
expanded into thousands of probe points. Default value is 128.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
---

tools/perf/Documentation/perf-probe.txt | 3 +++
tools/perf/builtin-probe.c | 9 ++++++++-
tools/perf/util/probe-event.c | 17 ++++++++++-------
tools/perf/util/probe-event.h | 4 ++--
tools/perf/util/probe-finder.c | 11 ++++++-----
tools/perf/util/probe-finder.h | 6 ++++--
6 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 63c25d3..94a258c 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -62,6 +62,9 @@ OPTIONS
Dry run. With this option, --add and --del doesn't execute actual
adding and removal operations.

+--max-probes::
+ Set the maximum number of probe points for an event. Default is 128.
+
PROBE SYNTAX
------------
Probe points are defined by following syntax.
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index c1e5403..61c6d70 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -54,6 +54,7 @@ static struct {
struct perf_probe_event events[MAX_PROBES];
struct strlist *dellist;
struct line_range line_range;
+ int max_probe_points;
} params;


@@ -179,6 +180,8 @@ static const struct option options[] = {
"file", "vmlinux pathname"),
#endif
OPT__DRY_RUN(&probe_event_dry_run),
+ OPT_INTEGER('\0', "max-probes", &params.max_probe_points,
+ "Set how many probe points can be found for a probe."),
OPT_END()
};

@@ -200,6 +203,9 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
}
}

+ if (params.max_probe_points == 0)
+ params.max_probe_points = MAX_PROBES;
+
if ((!params.nevents && !params.dellist && !params.list_events &&
!params.show_lines))
usage_with_options(probe_usage, options);
@@ -246,7 +252,8 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)

if (params.nevents) {
ret = add_perf_probe_events(params.events, params.nevents,
- params.force_add);
+ params.force_add,
+ params.max_probe_points);
if (ret < 0) {
pr_err(" Error: Failed to add events. (%d)\n", ret);
return ret;
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 5d3baec..9ded38c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -150,7 +150,8 @@ static int convert_to_perf_probe_point(struct kprobe_trace_point *tp,

/* Try to find perf_probe_event with debuginfo */
static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
- struct kprobe_trace_event **tevs)
+ struct kprobe_trace_event **tevs,
+ int max_tevs)
{
bool need_dwarf = perf_probe_event_need_dwarf(pev);
int fd, ntevs;
@@ -166,7 +167,7 @@ static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
}

/* Searching trace events corresponding to probe event */
- ntevs = find_kprobe_trace_events(fd, pev, tevs);
+ ntevs = find_kprobe_trace_events(fd, pev, tevs, max_tevs);
close(fd);

if (ntevs > 0) { /* Succeeded to find trace events */
@@ -318,7 +319,8 @@ static int convert_to_perf_probe_point(struct kprobe_trace_point *tp,
}

static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
- struct kprobe_trace_event **tevs __unused)
+ struct kprobe_trace_event **tevs __unused,
+ int max_tevs __unused)
{
if (perf_probe_event_need_dwarf(pev)) {
pr_warning("Debuginfo-analysis is not supported.\n");
@@ -1408,14 +1410,15 @@ static int __add_kprobe_trace_events(struct perf_probe_event *pev,
}

static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
- struct kprobe_trace_event **tevs)
+ struct kprobe_trace_event **tevs,
+ int max_tevs)
{
struct symbol *sym;
int ret = 0, i;
struct kprobe_trace_event *tev;

/* Convert perf_probe_event with debuginfo */
- ret = try_to_find_kprobe_trace_events(pev, tevs);
+ ret = try_to_find_kprobe_trace_events(pev, tevs, max_tevs);
if (ret != 0)
return ret;

@@ -1487,7 +1490,7 @@ struct __event_package {
};

int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
- bool force_add)
+ bool force_add, int max_tevs)
{
int i, j, ret;
struct __event_package *pkgs;
@@ -1506,7 +1509,7 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
pkgs[i].pev = &pevs[i];
/* Convert with or without debuginfo */
ret = convert_to_kprobe_trace_events(pkgs[i].pev,
- &pkgs[i].tevs);
+ &pkgs[i].tevs, max_tevs);
if (ret < 0)
goto end;
pkgs[i].ntevs = ret;
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index e7ff0d0..e9db1a2 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -115,8 +115,8 @@ extern void clear_kprobe_trace_event(struct kprobe_trace_event *tev);
extern int parse_line_range_desc(const char *cmd, struct line_range *lr);


-extern int add_perf_probe_events(struct perf_probe_event *pevs, int ntevs,
- bool force_add);
+extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
+ bool force_add, int max_probe_points);
extern int del_perf_probe_events(struct strlist *dellist);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 57b51ca..e3e3c1e 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -677,8 +677,9 @@ static int convert_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf)
Dwarf_Attribute fb_attr;
size_t nops;

- if (pf->ntevs == MAX_PROBES) {
- pr_warning("Too many( > %d) probe point found.\n", MAX_PROBES);
+ if (pf->ntevs == pf->max_tevs) {
+ pr_warning("Too many( > %d) probe point found.\n",
+ pf->max_tevs);
return -ERANGE;
}
tev = &pf->tevs[pf->ntevs++];
@@ -983,9 +984,9 @@ static int find_probe_point_by_func(struct probe_finder *pf)

/* Find kprobe_trace_events specified by perf_probe_event from debuginfo */
int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
- struct kprobe_trace_event **tevs)
+ struct kprobe_trace_event **tevs, int max_tevs)
{
- struct probe_finder pf = {.pev = pev};
+ struct probe_finder pf = {.pev = pev, .max_tevs = max_tevs};
struct perf_probe_point *pp = &pev->point;
Dwarf_Off off, noff;
size_t cuhl;
@@ -993,7 +994,7 @@ int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
Dwarf *dbg;
int ret = 0;

- pf.tevs = zalloc(sizeof(struct kprobe_trace_event) * MAX_PROBES);
+ pf.tevs = zalloc(sizeof(struct kprobe_trace_event) * max_tevs);
if (pf.tevs == NULL)
return -ENOMEM;
*tevs = pf.tevs;
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 310ce89..66f1980 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -18,7 +18,8 @@ static inline int is_c_varname(const char *name)
#ifdef DWARF_SUPPORT
/* Find kprobe_trace_events specified by perf_probe_event from debuginfo */
extern int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
- struct kprobe_trace_event **tevs);
+ struct kprobe_trace_event **tevs,
+ int max_tevs);

/* Find a perf_probe_point from debuginfo */
extern int find_perf_probe_point(int fd, unsigned long addr,
@@ -32,7 +33,8 @@ extern int find_line_range(int fd, struct line_range *lr);
struct probe_finder {
struct perf_probe_event *pev; /* Target probe event */
struct kprobe_trace_event *tevs; /* Result trace events */
- int ntevs; /* number of trace events */
+ int ntevs; /* Number of trace events */
+ int max_tevs; /* Max number of trace events */

/* For function searching */
int lno; /* Line number */

--
Masami Hiramatsu
e-mail: mhiramat@redhat.com


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