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Subject[PATCH v1 1/4] perf sched: Avoid large stack allocations
From
Commit 5ded57ac1bdb ("perf inject: Remove static variables") moved
static variables to local, however, in this case 3 MAX_CPUS (4096)
sized arrays were moved onto the stack making the stack frame quite
large. Avoid the stack usage by dynamically allocating the arrays.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-sched.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index cc4ba506e119..2aeb3c8ac396 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -193,8 +193,8 @@ struct perf_sched {
* weird events, such as a task being switched away that is not current.
*/
struct perf_cpu max_cpu;
- u32 curr_pid[MAX_CPUS];
- struct thread *curr_thread[MAX_CPUS];
+ u32 *curr_pid;
+ struct thread **curr_thread;
char next_shortname1;
char next_shortname2;
unsigned int replay_repeat;
@@ -224,7 +224,7 @@ struct perf_sched {
u64 run_avg;
u64 all_runtime;
u64 all_count;
- u64 cpu_last_switched[MAX_CPUS];
+ u64 *cpu_last_switched;
struct rb_root_cached atom_root, sorted_atom_root, merged_atom_root;
struct list_head sort_list, cmp_pid;
bool force;
@@ -3599,7 +3599,22 @@ int cmd_sched(int argc, const char **argv)

mutex_init(&sched.start_work_mutex);
mutex_init(&sched.work_done_wait_mutex);
- for (i = 0; i < ARRAY_SIZE(sched.curr_pid); i++)
+ sched.curr_thread = calloc(MAX_CPUS, sizeof(*sched.curr_thread));
+ if (!sched.curr_thread) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ sched.cpu_last_switched = calloc(MAX_CPUS, sizeof(*sched.cpu_last_switched));
+ if (!sched.cpu_last_switched) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ sched.curr_pid = malloc(MAX_CPUS * sizeof(*sched.curr_pid));
+ if (!sched.curr_pid) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ for (i = 0; i < MAX_CPUS; i++)
sched.curr_pid[i] = -1;

argc = parse_options_subcommand(argc, argv, sched_options, sched_subcommands,
@@ -3668,6 +3683,9 @@ int cmd_sched(int argc, const char **argv)
}

out:
+ free(sched.curr_pid);
+ free(sched.cpu_last_switched);
+ free(sched.curr_thread);
mutex_destroy(&sched.start_work_mutex);
mutex_destroy(&sched.work_done_wait_mutex);

--
2.41.0.rc0.172.g3f132b7071-goog
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