Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 716c69fe authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf top: Fall back to cpu-clock-tick hrtimer sampling if no cycle counter available 



On architectures/CPUs without PMU support but with perfcounters
enabled 'perf top' currently fails because it cannot create a
cycle based hw-perfcounter.

Fall back to the cpu-clock-tick sw-perfcounter in this case, which
is hrtimer based and will always work (as long as perfcounters
is enabled).

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 743ee1f8

tools/perf/builtin-top.c

+68 −45
Original line number Original line Diff line number Diff line
@@ -527,17 +527,13 @@ static void mmap_read(void) 
	}

	}

}

}





static int __cmd_top(void)

int nr_poll;

int group_fd;



static void start_counter(int i, int counter)

{

{

	struct perf_counter_attr *attr;

	struct perf_counter_attr *attr;

	pthread_t thread;

	int i, counter, group_fd, nr_poll = 0;

	unsigned int cpu;

	unsigned int cpu;

	int ret;



	for (i = 0; i < nr_cpus; i++) {

		group_fd = -1;

		for (counter = 0; counter < nr_counters; counter++) {





	cpu = profile_cpu;

	cpu = profile_cpu;

	if (target_pid == -1 && profile_cpu == -1)

	if (target_pid == -1 && profile_cpu == -1)
@@ -548,14 +544,30 @@ static int __cmd_top(void) 
	attr->sample_type	= PERF_SAMPLE_IP | PERF_SAMPLE_TID;

	attr->sample_type	= PERF_SAMPLE_IP | PERF_SAMPLE_TID;

	attr->freq		= freq;

	attr->freq		= freq;





try_again:

	fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0);

	fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0);



	if (fd[i][counter] < 0) {

	if (fd[i][counter] < 0) {

		int err = errno;

		int err = errno;





				error("syscall returned with %d (%s)\n",

		error("sys_perf_counter_open() syscall returned with %d (%s)\n",

			fd[i][counter], strerror(err));

			fd[i][counter], strerror(err));



		if (err == EPERM)

		if (err == EPERM)

					printf("Are you root?\n");

			die(" No permission - are you root?\n");

		/*

		 * If it's cycles then fall back to hrtimer

		 * based cpu-clock-tick sw counter, which

		 * is always available even if no PMU support:

		 */

		if (attr->type == PERF_TYPE_HARDWARE

			&& attr->config == PERF_COUNT_CPU_CYCLES) {



			warning(" ... trying to fall back to cpu-clock-ticks\n");

			attr->type = PERF_TYPE_SOFTWARE;

			attr->config = PERF_COUNT_CPU_CLOCK;

			goto try_again;

		}

		exit(-1);

		exit(-1);

	}

	}

	assert(fd[i][counter] >= 0);

	assert(fd[i][counter] >= 0);
@@ -579,6 +591,17 @@ static int __cmd_top(void) 
	if (mmap_array[i][counter].base == MAP_FAILED)

	if (mmap_array[i][counter].base == MAP_FAILED)

		die("failed to mmap with %d (%s)\n", errno, strerror(errno));

		die("failed to mmap with %d (%s)\n", errno, strerror(errno));

}

}



static int __cmd_top(void)

{

	pthread_t thread;

	int i, counter;

	int ret;



	for (i = 0; i < nr_cpus; i++) {

		group_fd = -1;

		for (counter = 0; counter < nr_counters; counter++)

			start_counter(i, counter);

	}

	}





	/* Wait for a minimal set of events before starting the snapshot */

	/* Wait for a minimal set of events before starting the snapshot */

tools/perf/util/usage.c

+5 −5
Original line number Original line Diff line number Diff line
@@ -14,24 +14,24 @@ static void report(const char *prefix, const char *err, va_list params) 




static NORETURN void usage_builtin(const char *err)

static NORETURN void usage_builtin(const char *err)

{

{

	fprintf(stderr, "\n usage: %s\n", err);

	fprintf(stderr, "\n Usage: %s\n", err);

	exit(129);

	exit(129);

}

}





static NORETURN void die_builtin(const char *err, va_list params)

static NORETURN void die_builtin(const char *err, va_list params)

{

{

	report("fatal: ", err, params);

	report(" Fatal: ", err, params);

	exit(128);

	exit(128);

}

}





static void error_builtin(const char *err, va_list params)

static void error_builtin(const char *err, va_list params)

{

{

	report("error: ", err, params);

	report(" Error: ", err, params);

}

}





static void warn_builtin(const char *warn, va_list params)

static void warn_builtin(const char *warn, va_list params)

{

{

	report("warning: ", warn, params);

	report(" Warning: ", warn, params);

}

}





/* If we are in a dlopen()ed .so write to a global variable would segfault

/* If we are in a dlopen()ed .so write to a global variable would segfault