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Subject[PATCH] tracing/filters: Defer pred allocation
init_preds() allocates about 5392 bytes of memory (on x86_32) for
a TRACE_EVENT. With my config, at system boot total memory occupied
is:

5392 * (642 + 15) == 3459KB

642 == cat available_events | wc -l
15 == number of dirs in events/ftrace
That's quite a lot, so we'd better defer memory allocation util
it's needed, that's when filter is used.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
tracing/kprobe needs rebase after this patch..

---
include/linux/ftrace_event.h | 1 -
include/linux/syscalls.h | 2 -
include/trace/ftrace.h | 1 -
kernel/trace/trace_events_filter.c | 50 +++++++++++++++++++++++++++++------
kernel/trace/trace_export.c | 1 -
5 files changed, 41 insertions(+), 14 deletions(-)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index ace2da9..7554804 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -133,7 +133,6 @@ struct ftrace_event_call {
#define MAX_FILTER_PRED 32
#define MAX_FILTER_STR_VAL 128

-extern int init_preds(struct ftrace_event_call *call);
extern void destroy_preds(struct ftrace_event_call *call);
extern int filter_match_preds(struct ftrace_event_call *call, void *rec);
extern int filter_current_check_discard(struct ftrace_event_call *call,
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f124c89..a8e3782 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -177,7 +177,6 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
event_enter_##sname.id = id; \
set_syscall_enter_id(num, id); \
INIT_LIST_HEAD(&event_enter_##sname.fields); \
- init_preds(&event_enter_##sname); \
return 0; \
} \
TRACE_SYS_ENTER_PROFILE(sname); \
@@ -214,7 +213,6 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
event_exit_##sname.id = id; \
set_syscall_exit_id(num, id); \
INIT_LIST_HEAD(&event_exit_##sname.fields); \
- init_preds(&event_exit_##sname); \
return 0; \
} \
TRACE_SYS_EXIT_PROFILE(sname); \
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 57c56a9..bfbc842 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -622,7 +622,6 @@ static int ftrace_raw_init_event_##call(void) \
return -ENODEV; \
event_##call.id = id; \
INIT_LIST_HEAD(&event_##call.fields); \
- init_preds(&event_##call); \
return 0; \
} \
\
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 9f03082..c6b2edf 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -309,7 +309,7 @@ void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
struct event_filter *filter = call->filter;

mutex_lock(&event_mutex);
- if (filter->filter_string)
+ if (filter && filter->filter_string)
trace_seq_printf(s, "%s\n", filter->filter_string);
else
trace_seq_printf(s, "none\n");
@@ -322,7 +322,7 @@ void print_subsystem_event_filter(struct event_subsystem *system,
struct event_filter *filter = system->filter;

mutex_lock(&event_mutex);
- if (filter->filter_string)
+ if (filter && filter->filter_string)
trace_seq_printf(s, "%s\n", filter->filter_string);
else
trace_seq_printf(s, "none\n");
@@ -390,6 +390,9 @@ void destroy_preds(struct ftrace_event_call *call)
struct event_filter *filter = call->filter;
int i;

+ if (!filter)
+ return;
+
for (i = 0; i < MAX_FILTER_PRED; i++) {
if (filter->preds[i])
filter_free_pred(filter->preds[i]);
@@ -400,7 +403,7 @@ void destroy_preds(struct ftrace_event_call *call)
call->filter = NULL;
}

-int init_preds(struct ftrace_event_call *call)
+static int init_preds(struct ftrace_event_call *call)
{
struct event_filter *filter;
struct filter_pred *pred;
@@ -410,7 +413,6 @@ int init_preds(struct ftrace_event_call *call)
if (!call->filter)
return -ENOMEM;

- call->filter_active = 0;
filter->n_preds = 0;

filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred), GFP_KERNEL);
@@ -432,7 +434,28 @@ oom:

return -ENOMEM;
}
-EXPORT_SYMBOL_GPL(init_preds);
+
+static int init_subsystem_preds(struct event_subsystem *system)
+{
+ struct ftrace_event_call *call;
+ int err;
+
+ list_for_each_entry(call, &ftrace_events, list) {
+ if (!call->define_fields)
+ continue;
+
+ if (strcmp(call->system, system->name) != 0)
+ continue;
+
+ if (!call->filter) {
+ err = init_preds(call);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}

enum {
FILTER_DISABLE_ALL,
@@ -449,6 +472,9 @@ static void filter_free_subsystem_preds(struct event_subsystem *system,
if (!call->define_fields)
continue;

+ if (strcmp(call->system, system->name) != 0)
+ continue;
+
if (flag == FILTER_INIT_NO_RESET) {
call->filter->no_reset = false;
continue;
@@ -457,10 +483,8 @@ static void filter_free_subsystem_preds(struct event_subsystem *system,
if (flag == FILTER_SKIP_NO_RESET && call->filter->no_reset)
continue;

- if (!strcmp(call->system, system->name)) {
- filter_disable_preds(call);
- remove_filter_string(call->filter);
- }
+ filter_disable_preds(call);
+ remove_filter_string(call->filter);
}
}

@@ -1094,6 +1118,10 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)

mutex_lock(&event_mutex);

+ err = init_preds(call);
+ if (err)
+ goto out_unlock;
+
if (!strcmp(strstrip(filter_string), "0")) {
filter_disable_preds(call);
remove_filter_string(call->filter);
@@ -1139,6 +1167,10 @@ int apply_subsystem_event_filter(struct event_subsystem *system,

mutex_lock(&event_mutex);

+ err = init_subsystem_preds(system);
+ if (err)
+ goto out_unlock;
+
if (!strcmp(strstrip(filter_string), "0")) {
filter_free_subsystem_preds(system, FILTER_DISABLE_ALL);
remove_filter_string(system->filter);
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index 029a91f..df1bf6e 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -135,7 +135,6 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
static int ftrace_raw_init_event_##call(void) \
{ \
INIT_LIST_HEAD(&event_##call.fields); \
- init_preds(&event_##call); \
return 0; \
} \

--
1.6.3


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