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1 /*
2 ** Copyright 2010 The Android Open Source Project
3 **
4 ** Licensed under the Apache License, Version 2.0 (the "License");
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
8 **     http://www.apache.org/licenses/LICENSE-2.0
9 **
10 ** Unless required by applicable law or agreed to in writing, software
11 ** distributed under the License is distributed on an "AS IS" BASIS,
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16 
17 
18 /* Opens /proc/sched_stat and diff's the counters.
19    Currently support version 15, modify parse() to support other
20    versions
21 */
22 
23 #include <stdlib.h>
24 #include <stdio.h>
25 #include <errno.h>
26 #include <sys/uio.h>
27 #include <unistd.h>
28 #include <sys/time.h>
29 #include <fcntl.h>
30 
31 #define MAX_CPU 2
32 
33 struct cpu_stat {
34     /* sched_yield() stats */
35     unsigned int yld_count;  /* sched_yield() called */
36 
37     /* schedule() stats */
38     unsigned int sched_switch;  /* switched to expired queue and reused it */
39     unsigned int sched_count;  /* schedule() called */
40     unsigned int sched_goidle;  /* schedule() left the cpu idle */
41 
42     /* try_to_wake_up() stats */
43     unsigned int ttwu_count;  /* try_to_wake_up() called */
44     /* try_to_wake_up() called and found the process being awakened last ran on
45      * the waking cpu */
46     unsigned int ttwu_local;
47 
48     /* latency stats */
49     unsigned long long cpu_time;  /* time spent running by tasks (ms) */
50     unsigned long long run_delay; /* time spent waiting to run by tasks (ms) */
51     unsigned long pcount;  /* number of tasks (not necessarily unique) given */
52 };
53 
54 struct cpu_stat cpu_prev[MAX_CPU];
55 struct cpu_stat cpu_delta[MAX_CPU];
56 struct cpu_stat tmp;
57 
next_line(const char * b)58 static const char *next_line(const char *b) {
59     while (1) {
60         switch (*b) {
61         case '\n':
62             return b + 1;
63         case '\0':
64             return NULL;
65         }
66         b++;
67     }
68 }
print()69 static int print() {
70     int i;
71 
72     printf("CPU  yield() schedule() switch idle   ttwu() local  cpu_time wait_time timeslices\n");
73     for (i=0; i<MAX_CPU; i++) {
74         printf(" %2d  %7u %10u %6u %4u %8u %5u %9llu %9llu %10lu\n",
75             i,
76             cpu_delta[i].yld_count,
77             cpu_delta[i].sched_count, cpu_delta[i].sched_switch, cpu_delta[i].sched_goidle,
78             cpu_delta[i].ttwu_count, cpu_delta[i].ttwu_local,
79             cpu_delta[i].cpu_time / 1000000, cpu_delta[i].run_delay / 1000000, cpu_delta[i].pcount);
80     }
81     return 0;
82 }
83 
parse_cpu_v15(const char * b)84 static int parse_cpu_v15(const char *b) {
85     int cpu;
86 
87     if (sscanf(b, "cpu%d %u %u %u %u %u %u %llu %llu %lu\n",
88             &cpu, &tmp.yld_count,
89             &tmp.sched_switch, &tmp.sched_count, &tmp.sched_goidle,
90             &tmp.ttwu_count, &tmp.ttwu_local,
91             &tmp.cpu_time, &tmp.run_delay, &tmp.pcount) != 10) {
92         printf("Could not parse %s\n", b);
93         return -1;
94     }
95 
96     cpu_delta[cpu].yld_count = tmp.yld_count - cpu_prev[cpu].yld_count;
97     cpu_delta[cpu].sched_switch = tmp.sched_switch - cpu_prev[cpu].sched_switch;
98     cpu_delta[cpu].sched_count = tmp.sched_count - cpu_prev[cpu].sched_count;
99     cpu_delta[cpu].sched_goidle = tmp.sched_goidle - cpu_prev[cpu].sched_goidle;
100     cpu_delta[cpu].ttwu_count = tmp.ttwu_count - cpu_prev[cpu].ttwu_count;
101     cpu_delta[cpu].ttwu_local = tmp.ttwu_local - cpu_prev[cpu].ttwu_local;
102     cpu_delta[cpu].cpu_time = tmp.cpu_time - cpu_prev[cpu].cpu_time;
103     cpu_delta[cpu].run_delay = tmp.run_delay - cpu_prev[cpu].run_delay;
104     cpu_delta[cpu].pcount = tmp.pcount - cpu_prev[cpu].pcount;
105 
106     cpu_prev[cpu] = tmp;
107     return 0;
108 }
109 
110 
parse(const char * b)111 static int parse(const char *b) {
112     unsigned int version;
113     unsigned long long ts;
114 
115     if (sscanf(b, "version %u\n", &version) != 1) {
116         printf("Could not parse version\n");
117         return -1;
118     }
119     switch (version) {
120     case 15:
121         b = next_line(b);
122         if (!b || sscanf(b, "timestamp %llu\n", &ts) != 1) {
123             printf("Could not parse timestamp\n");
124             return -1;
125         }
126         while (1) {
127             b = next_line(b);
128             if (!b) break;
129             if (b[0] == 'c') {
130                 if (parse_cpu_v15(b)) return -1;
131             }
132         }
133         break;
134     default:
135         printf("Can not handle version %u\n", version);
136         return -1;
137     }
138     return 0;
139 }
140 
main(int argc,char ** argv)141 int main(int argc, char **argv) {
142     int i;
143     int fd;
144     char buf[4096];
145 
146     while (1) {
147         fd = open("/proc/schedstat", O_RDONLY);
148         if (fd < 0) return -1;
149         i = read(fd, buf, sizeof(buf) - 1);
150         close(fd);
151         buf[i] = '\0';
152         if (parse(buf)) return -1;
153         print();
154         sleep(1);
155     }
156     return 0;
157 }
158