Commit 04ed4ccb authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf synthetic-events: save 4kb from 2 stack frames 



Reuse an existing char buffer to avoid two PATH_MAX sized char buffers.

Reduces stack frame sizes by 4kb.

perf_event__synthesize_mmap_events before 'sub $0x45b8,%rsp' after
'sub $0x35b8,%rsp'.

perf_event__get_comm_ids before 'sub $0x2028,%rsp' after
'sub $0x1028,%rsp'.

The performance impact of this change is negligible.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200402154357.107873-4-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c6fddb28

tools/perf/util/synthetic-events.c

+10 −12
Original line number Diff line number Diff line
@@ -71,7 +71,6 @@ int perf_tool__process_synth_event(struct perf_tool *tool, 
static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,

				    pid_t *tgid, pid_t *ppid)

{

	char filename[PATH_MAX];

	char bf[4096];

	int fd;

	size_t size = 0;
@@ -81,11 +80,11 @@ static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, 
	*tgid = -1;

	*ppid = -1;



	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);

	snprintf(bf, sizeof(bf), "/proc/%d/status", pid);



	fd = open(filename, O_RDONLY);

	fd = open(bf, O_RDONLY);

	if (fd < 0) {

		pr_debug("couldn't open %s\n", filename);

		pr_debug("couldn't open %s\n", bf);

		return -1;

	}
@@ -281,9 +280,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
				       struct machine *machine,

				       bool mmap_data)

{

	char filename[PATH_MAX];

	FILE *fp;

	unsigned long long t;

	char bf[BUFSIZ];

	bool truncation = false;

	unsigned long long timeout = proc_map_timeout * 1000000ULL;

	int rc = 0;
@@ -293,15 +292,15 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
	if (machine__is_default_guest(machine))

		return 0;



	snprintf(filename, sizeof(filename), "%s/proc/%d/task/%d/maps",

	snprintf(bf, sizeof(bf), "%s/proc/%d/task/%d/maps",

		machine->root_dir, pid, pid);



	fp = fopen(filename, "r");

	fp = fopen(bf, "r");

	if (fp == NULL) {

		/*

		 * We raced with a task exiting - just return:

		 */

		pr_debug("couldn't open %s\n", filename);

		pr_debug("couldn't open %s\n", bf);

		return -1;

	}
@@ -309,7 +308,6 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
	t = rdclock();



	while (1) {

		char bf[BUFSIZ];

		char prot[5];

		char execname[PATH_MAX];

		char anonstr[] = "//anon";
@@ -321,10 +319,10 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
			break;



		if ((rdclock() - t) > timeout) {

			pr_warning("Reading %s time out. "

			pr_warning("Reading %s/proc/%d/task/%d/maps time out. "

				   "You may want to increase "

				   "the time limit by --proc-map-timeout\n",

				   filename);

				   machine->root_dir, pid, pid);

			truncation = true;

			goto out;

		}