Commit 9dd49988 authored by Mike Galbraith's avatar Mike Galbraith Committed by Ingo Molnar
Browse files

perf_counter tools: kerneltop: add real-time data acquisition thread 



Decouple kerneltop display from event acquisition by introducing
a separate data acquisition thread. This fixes annnoying kerneltop
display refresh jitter and missed events.

Also add a -r <prio> option, to switch the data acquisition thread
to real-time priority.

Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Orig-LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 4e935e47

Documentation/perf_counter/kerneltop.c

+39 −18
Original line number Diff line number Diff line
@@ -77,6 +77,8 @@ 
#include <errno.h>

#include <ctype.h>

#include <time.h>

#include <sched.h>

#include <pthread.h>



#include <sys/syscall.h>

#include <sys/ioctl.h>
@@ -181,6 +183,7 @@ static int tid = -1; 
static int			profile_cpu			= -1;

static int			nr_cpus				=  0;

static int			nmi				=  1;

static unsigned int		realtime_prio			=  0;

static int			group				=  0;

static unsigned int		page_size;

static unsigned int		mmap_pages			=  16;
@@ -334,6 +337,7 @@ static void display_help(void) 
	" -l                           # show scale factor for RR events\n"

	" -d delay  --delay=<seconds>  # sampling/display delay           [default:  2]\n"

	" -f CNT    --filter=CNT       # min-event-count filter          [default: 100]\n\n"

	" -r prio   --realtime=<prio>  # event acquisition runs with SCHED_FIFO policy\n"

	" -s symbol --symbol=<symbol>  # function to be showed annotated one-shot\n"

	" -x path   --vmlinux=<path>   # the vmlinux binary, required for -s use\n"

	" -z        --zero             # zero counts after display\n"
@@ -620,7 +624,6 @@ static int compare(const void *__sym1, const void *__sym2) 
	return sym_weight(sym1) < sym_weight(sym2);

}



static time_t			last_refresh;

static long			events;

static long			userspace_events;

static const char		CONSOLE_CLEAR[] = "";
@@ -634,6 +637,7 @@ static void print_sym_table(void) 
	float events_per_sec = events/delay_secs;

	float kevents_per_sec = (events-userspace_events)/delay_secs;



	events = userspace_events = 0;

	memcpy(tmp, sym_table, sizeof(sym_table[0])*sym_table_count);

	qsort(tmp, sym_table_count, sizeof(tmp[0]), compare);
@@ -714,8 +718,6 @@ static void print_sym_table(void) 
	if (sym_filter_entry)

		show_details(sym_filter_entry);



	last_refresh = time(NULL);



	{

		struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
@@ -726,6 +728,16 @@ static void print_sym_table(void) 
	}

}



static void *display_thread(void *arg)

{

	printf("KernelTop refresh period: %d seconds\n", delay_secs);



	while (!sleep(delay_secs))

		print_sym_table();



	return NULL;

}



static int read_symbol(FILE *in, struct sym_entry *s)

{

	static int filter_match = 0;
@@ -1081,19 +1093,20 @@ static void process_options(int argc, char *argv[]) 
			{"filter",	required_argument,	NULL, 'f'},

			{"group",	required_argument,	NULL, 'g'},

			{"help",	no_argument,		NULL, 'h'},

			{"scale",	no_argument,		NULL, 'l'},

			{"nmi",		required_argument,	NULL, 'n'},

			{"mmap_info",	no_argument,		NULL, 'M'},

			{"mmap_pages",	required_argument,	NULL, 'm'},

			{"munmap_info",	no_argument,		NULL, 'U'},

			{"pid",		required_argument,	NULL, 'p'},

			{"vmlinux",	required_argument,	NULL, 'x'},

			{"realtime",	required_argument,	NULL, 'r'},

			{"scale",	no_argument,		NULL, 'l'},

			{"symbol",	required_argument,	NULL, 's'},

			{"stat",	no_argument,		NULL, 'S'},

			{"vmlinux",	required_argument,	NULL, 'x'},

			{"zero",	no_argument,		NULL, 'z'},

			{"mmap_pages",	required_argument,	NULL, 'm'},

			{"mmap_info",	no_argument,		NULL, 'M'},

			{"munmap_info",	no_argument,		NULL, 'U'},

			{NULL,		0,			NULL,  0 }

		};

		int c = getopt_long(argc, argv, "+:ac:C:d:De:f:g:hln:m:p:s:Sx:zMU",

		int c = getopt_long(argc, argv, "+:ac:C:d:De:f:g:hln:m:p:r:s:Sx:zMU",

				    long_options, &option_index);

		if (c == -1)

			break;
@@ -1127,6 +1140,7 @@ static void process_options(int argc, char *argv[]) 
				profile_cpu = -1;

			}

			tid				=   atoi(optarg); break;

		case 'r': realtime_prio			=   atoi(optarg); break;

		case 's': sym_filter			= strdup(optarg); break;

		case 'S': run_perfstat			=	       1; break;

		case 'x': vmlinux			= strdup(optarg); break;
@@ -1289,6 +1303,7 @@ int main(int argc, char *argv[]) 
	struct pollfd event_array[MAX_NR_CPUS * MAX_COUNTERS];

	struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];

	struct perf_counter_hw_event hw_event;

	pthread_t thread;

	int i, counter, group_fd, nr_poll = 0;

	unsigned int cpu;

	int ret;
@@ -1363,8 +1378,20 @@ int main(int argc, char *argv[]) 
		}

	}



	printf("KernelTop refresh period: %d seconds\n", delay_secs);

	last_refresh = time(NULL);

	if (pthread_create(&thread, NULL, display_thread, NULL)) {

		printf("Could not create display thread.\n");

		exit(-1);

	}



	if (realtime_prio) {

		struct sched_param param;



		param.sched_priority = realtime_prio;

		if (sched_setscheduler(0, SCHED_FIFO, &param)) {

			printf("Could not set realtime priority.\n");

			exit(-1);

		}

	}



	while (1) {

		int hits = events;
@@ -1374,14 +1401,8 @@ int main(int argc, char *argv[]) 
				mmap_read(&mmap_array[i][counter]);

		}



		if (time(NULL) >= last_refresh + delay_secs) {

			print_sym_table();

			events = userspace_events = 0;

		}



		if (hits == events)

			ret = poll(event_array, nr_poll, 1000);

		hits = events;

			ret = poll(event_array, nr_poll, 100);

	}



	return 0;

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