[tip:perfcounters/core] perf_counter tools: kerneltop: add real-time data acquisition thread

Mike Galbraith
2009-04-01T10:20:38Z

Commit-ID: f0e36dc28173b65df2216dfae7109645d97a1bd9
Gitweb: http://git.kernel.org/tip/f0e36dc28173b65df2216dfae7109645d97a1bd9
Author: Mike Galbraith <efault@gmx.de>
AuthorDate: Fri, 27 Mar 2009 12:13:43 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 1 Apr 2009 12:08:51 +0200

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: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
Documentation/perf_counter/kerneltop.c | 57 ++++++++++++++++++++++----------
1 files changed, 39 insertions(+), 18 deletions(-)

diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c
index 430810d..33b4fcf 100644
--- a/Documentation/perf_counter/kerneltop.c
+++ b/Documentation/perf_counter/kerneltop.c
@@ -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[] = "^[[H^[[2J";
@@ -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;