/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define MAX_LINE 512
#define MAX_FILENAME 64
const char *EXPECTED_VERSION = "Latency Top version : v0.1\n";
const char *SYSCTL_FILE = "/proc/sys/kernel/latencytop";
const char *GLOBAL_STATS_FILE = "/proc/latency_stats";
const char *THREAD_STATS_FILE_FORMAT = "/proc/%d/task/%d/latency";
struct latency_entry {
struct latency_entry *next;
unsigned long count;
unsigned long max;
unsigned long total;
char reason[MAX_LINE];
};
static inline void check_latencytop() { }
static struct latency_entry *read_global_stats(struct latency_entry *list, int erase);
static struct latency_entry *read_process_stats(struct latency_entry *list, int erase, int pid);
static struct latency_entry *read_thread_stats(struct latency_entry *list, int erase, int pid, int tid, int fatal);
static struct latency_entry *alloc_latency_entry(void);
static void free_latency_entry(struct latency_entry *e);
static void set_latencytop(int on);
static struct latency_entry *read_latency_file(FILE *f, struct latency_entry *list);
static void erase_latency_file(FILE *f);
static struct latency_entry *find_latency_entry(struct latency_entry *e, char *reason);
static void print_latency_entries(struct latency_entry *head);
static void signal_handler(int sig);
static void disable_latencytop(void);
static int numcmp(const long long a, const long long b);
static int lat_cmp(const void *a, const void *b);
static void clear_screen(void);
static void usage(const char *cmd);
struct latency_entry *free_entries;
int main(int argc, char *argv[]) {
struct latency_entry *e;
int delay, iterations;
int pid, tid;
int count, erase;
int i;
delay = 1;
iterations = 0;
pid = tid = 0;
for (i = 1; i < argc; i++) {
if (!strcmp(argv[i], "-d")) {
if (i >= argc - 1) {
fprintf(stderr, "Option -d expects an argument.\n");
exit(EXIT_FAILURE);
}
delay = atoi(argv[++i]);
continue;
}
if (!strcmp(argv[i], "-n")) {
if (i >= argc - 1) {
fprintf(stderr, "Option -n expects an argument.\n");
exit(EXIT_FAILURE);
}
iterations = atoi(argv[++i]);
continue;
}
if (!strcmp(argv[i], "-h")) {
usage(argv[0]);
exit(EXIT_SUCCESS);
}
if (!strcmp(argv[i], "-p")) {
if (i >= argc - 1) {
fprintf(stderr, "Option -p expects an argument.\n");
exit(EXIT_FAILURE);
}
pid = atoi(argv[++i]);
continue;
}
if (!strcmp(argv[i], "-t")) {
if (i >= argc - 1) {
fprintf(stderr, "Option -t expects an argument.\n");
exit(EXIT_FAILURE);
}
tid = atoi(argv[++i]);
continue;
}
fprintf(stderr, "Invalid argument \"%s\".\n", argv[i]);
usage(argv[0]);
exit(EXIT_FAILURE);
}
if (tid && !pid) {
fprintf(stderr, "If you provide a thread ID with -t, you must provide a process ID with -p.\n");
exit(EXIT_FAILURE);
}
check_latencytop();
free_entries = NULL;
signal(SIGINT, &signal_handler);
signal(SIGTERM, &signal_handler);
atexit(&disable_latencytop);
set_latencytop(1);
count = 0;
erase = 1;
while ((iterations == 0) || (count++ < iterations)) {
sleep(delay);
e = NULL;
if (pid) {
if (tid) {
e = read_thread_stats(e, erase, pid, tid, 1);
} else {
e = read_process_stats(e, erase, pid);
}
} else {
e = read_global_stats(e, erase);
}
erase = 0;
clear_screen();
if (pid) {
if (tid) {
printf("Latencies for thread %d in process %d:\n", tid, pid);
} else {
printf("Latencies for process %d:\n", pid);
}
} else {
printf("Latencies across all processes:\n");
}
print_latency_entries(e);
}
set_latencytop(0);
return 0;
}
static struct latency_entry *read_global_stats(struct latency_entry *list, int erase) {
FILE *f;
struct latency_entry *e;
if (erase) {
f = fopen(GLOBAL_STATS_FILE, "w");
if (!f) {
fprintf(stderr, "Could not open global latency stats file: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(f, "erase\n");
fclose(f);
}
f = fopen(GLOBAL_STATS_FILE, "r");
if (!f) {
fprintf(stderr, "Could not open global latency stats file: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
e = read_latency_file(f, list);
fclose(f);
return e;
}
static struct latency_entry *read_process_stats(struct latency_entry *list, int erase, int pid) {
char dirname[MAX_FILENAME];
DIR *dir;
struct dirent *ent;
struct latency_entry *e;
int tid;
sprintf(dirname, "/proc/%d/task", pid);
dir = opendir(dirname);
if (!dir) {
fprintf(stderr, "Could not open task dir for process %d.\n", pid);
fprintf(stderr, "Perhaps the process has terminated?\n");
exit(EXIT_FAILURE);
}
e = list;
while ((ent = readdir(dir))) {
if (!isdigit(ent->d_name[0]))
continue;
tid = atoi(ent->d_name);
e = read_thread_stats(e, erase, pid, tid, 0);
}
closedir(dir);
return e;
}
static struct latency_entry *read_thread_stats(struct latency_entry *list, int erase, int pid, int tid, int fatal) {
char filename[MAX_FILENAME];
FILE *f;
struct latency_entry *e;
sprintf(filename, THREAD_STATS_FILE_FORMAT, pid, tid);
if (erase) {
f = fopen(filename, "w");
if (!f) {
if (fatal) {
fprintf(stderr, "Could not open %s: %s\n", filename, strerror(errno));
fprintf(stderr, "Perhaps the process or thread has terminated?\n");
exit(EXIT_FAILURE);
} else {
return list;
}
}
fprintf(f, "erase\n");
fclose(f);
}
f = fopen(GLOBAL_STATS_FILE, "r");
if (!f) {
if (fatal) {
fprintf(stderr, "Could not open %s: %s\n", filename, strerror(errno));
fprintf(stderr, "Perhaps the process or thread has terminated?\n");
exit(EXIT_FAILURE);
} else {
return list;
}
}
e = read_latency_file(f, list);
fclose(f);
return e;
}
static struct latency_entry *alloc_latency_entry(void) {
struct latency_entry *e;
if (free_entries) {
e = free_entries;
free_entries = free_entries->next;
} else {
e = calloc(1, sizeof(struct latency_entry));
if (!e) {
fprintf(stderr, "Could not allocate latency entry: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
}
return e;
}
static void free_latency_entry(struct latency_entry *e) {
e->next = free_entries;
free_entries = e;
}
static struct latency_entry *find_latency_entry(struct latency_entry *head, char *reason) {
struct latency_entry *e;
e = head;
while (e) {
if (!strcmp(e->reason, reason))
return e;
e = e->next;
}
return NULL;
}
static void set_latencytop(int on) {
FILE *f;
f = fopen(SYSCTL_FILE, "w");
if (!f) {
fprintf(stderr, "Could not open %s: %s\n", SYSCTL_FILE, strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(f, "%d\n", on);
fclose(f);
}
static void erase_latency_file(FILE *f) {
fprintf(f, "erase\n");
}
static struct latency_entry *read_latency_file(FILE *f, struct latency_entry *list) {
struct latency_entry *e, *head;
char line[MAX_LINE];
unsigned long count, max, total;
char reason[MAX_LINE];
head = list;
if (!fgets(line, MAX_LINE, f)) {
fprintf(stderr, "Could not read latency file version: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (strcmp(line, EXPECTED_VERSION) != 0) {
fprintf(stderr, "Expected version: %s\n", EXPECTED_VERSION);
fprintf(stderr, "But got version: %s", line);
exit(EXIT_FAILURE);
}
while (fgets(line, MAX_LINE, f)) {
sscanf(line, "%ld %ld %ld %s", &count, &total, &max, reason);
if (max > 0 || total > 0) {
e = find_latency_entry(head, reason);
if (e) {
e->count += count;
if (max > e->max)
e->max = max;
e->total += total;
} else {
e = alloc_latency_entry();
e->count = count;
e->max = max;
e->total = total;
strcpy(e->reason, reason);
e->next = head;
head = e;
}
}
}
return head;
}
static void print_latency_entries(struct latency_entry *head) {
struct latency_entry *e, **array;
unsigned long average;
int i, count;
e = head;
count = 0;
while (e) {
count++;
e = e->next;
}
e = head;
array = calloc(count, sizeof(struct latency_entry *));
if (!array) {
fprintf(stderr, "Error allocating array: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
for (i = 0; i < count; i++) {
array[i] = e;
e = e->next;
}
qsort(array, count, sizeof(struct latency_entry *), &lat_cmp);
printf("%10s %10s %7s %s\n", "Maximum", "Average", "Count", "Reason");
for (i = 0; i < count; i++) {
e = array[i];
average = e->total / e->count;
printf("%4lu.%02lu ms %4lu.%02lu ms %7ld %s\n",
e->max / 1000, (e->max % 1000) / 10,
average / 1000, (average % 1000) / 10,
e->count,
e->reason);
}
free(array);
}
static void signal_handler(int sig) {
exit(EXIT_SUCCESS);
}
static void disable_latencytop(void) {
set_latencytop(0);
}
static void clear_screen(void) {
printf("\n\n");
}
static void usage(const char *cmd) {
fprintf(stderr, "Usage: %s [ -d delay ] [ -n iterations ] [ -p pid [ -t tid ] ] [ -h ]\n"
" -d delay Time to sleep between updates.\n"
" -n iterations Number of updates to show (0 = infinite).\n"
" -p pid Process to monitor (default is all).\n"
" -t tid Thread (within specified process) to monitor (default is all).\n"
" -h Display this help screen.\n",
cmd);
}
static int numcmp(const long long a, const long long b) {
if (a < b) return -1;
if (a > b) return 1;
return 0;
}
static int lat_cmp(const void *a, const void *b) {
const struct latency_entry *pa, *pb;
pa = (*((struct latency_entry **)a));
pb = (*((struct latency_entry **)b));
return numcmp(pb->max, pa->max);
}