lib/perf-counter.c

   1 /*
   2  * Copyright (c) 2015 Nicira, Inc.
   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 /* This implementation only applies to the Linux platform.  */
  18
  19 #include <config.h>
  20 #if defined(__linux__) && defined(HAVE_PERF_EVENT_H)
  21
  22 #include <stddef.h>
  23 #include <sys/types.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <sys/ioctl.h>
  27 #include <linux/perf_event.h>
  28 #include <asm/unistd.h>
  29 #include "dynamic-string.h"
  30 #include "openvswitch/vlog.h"
  31 #include "perf-counter.h"
  32 #include "shash.h"
  33 #include "util.h"
  34
  35 VLOG_DEFINE_THIS_MODULE(perf_counter);
  36
  37 static struct shash perf_counters;
  38 static int fd__ = 0;
  39
  40 uint64_t
  41 perf_counter_read(uint64_t *counter)
  42 {
  43     int size = sizeof *counter;
  44
  45     if (fd__ <= 0 || read(fd__, counter, size) < size) {
  46         *counter = 0;
  47     }
  48
  49     return *counter;
  50 }
  51
  52 static long
  53 perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
  54                 int cpu, int group_fd, unsigned long flags)
  55 {
  56     int ret;
  57
  58     ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
  59                   group_fd, flags);
  60     return ret;
  61 }
  62
  63 /* Set up perf event counters to read user space instruction counters
  64  * only for this process, on all cpus.   */
  65 static void
  66 perf_event_setup(void)
  67 {
  68     struct perf_event_attr pe;
  69
  70     memset(&pe, 0, sizeof(struct perf_event_attr));
  71     pe.type = PERF_TYPE_HARDWARE;
  72     pe.size = sizeof(struct perf_event_attr);
  73     pe.config = PERF_COUNT_HW_INSTRUCTIONS;
  74     pe.disabled = 1;
  75     pe.exclude_kernel = 1;
  76     pe.exclude_hv = 1;
  77
  78     fd__ = perf_event_open(&pe, 0, -1, -1, 0);
  79     if (fd__ == -1) {
  80         VLOG_INFO("Peformance counter is not available on this platform.");
  81     } else {
  82         ioctl(fd__, PERF_EVENT_IOC_RESET, 0);
  83         ioctl(fd__, PERF_EVENT_IOC_ENABLE, 0);
  84     }
  85 }
  86
  87 static void
  88 perf_counter_init(struct perf_counter *counter)
  89 {
  90     counter->once = true;
  91     shash_add_assert(&perf_counters, counter->name, counter);
  92 }
  93
  94 void
  95 perf_counter_accumulate(struct perf_counter *counter, uint64_t start_count)
  96 {
  97     uint64_t end_count;
  98
  99     if (!counter->once) {
 100         perf_counter_init(counter);
 101     }
 102
 103     counter->n_events++;
 104     perf_counter_read(&end_count);
 105     counter->total_count += end_count - start_count;
 106 }
 107
 108 static void
 109 perf_counter_to_ds(struct ds *ds, struct perf_counter *pfc)
 110 {
 111     double ratio;
 112
 113     if (pfc->n_events) {
 114         ratio = (double)pfc->total_count / (double)pfc->n_events;
 115     } else {
 116         ratio = 0.0;
 117     }
 118
 119     ds_put_format(ds, "%-40s%12"PRIu64"%12"PRIu64"%12.1f\n",
 120                   pfc->name, pfc->n_events, pfc->total_count, ratio);
 121 }
 122
 123 static void
 124 perf_counters_to_ds(struct ds *ds)
 125 {
 126     const char *err_str;
 127     const struct shash_node **sorted;
 128     int i;
 129
 130     err_str = NULL;
 131     if (fd__ == -1) {
 132         err_str = "performance counter is not supported on this platfrom";
 133     } else if (!shash_count(&perf_counters)) {
 134         err_str = "performance counter has never been hit";
 135     }
 136
 137     if (err_str) {
 138         ds_put_format(ds, "%s\n", err_str);
 139         return;
 140     }
 141
 142     /* Display counters in alphabetical order.  */
 143     sorted = shash_sort(&perf_counters);
 144     for (i = 0; i < shash_count(&perf_counters); i++) {
 145         perf_counter_to_ds(ds, sorted[i]->data);
 146     }
 147     free(sorted);
 148 }
 149
 150 /*
 151  * Caller is responsible for free memory.
 152  */
 153 char *
 154 perf_counters_to_string()
 155 {
 156     struct ds ds;
 157
 158     ds_init(&ds);
 159     perf_counters_to_ds(&ds);
 160     return ds_steal_cstr(&ds);
 161 }
 162
 163 void
 164 perf_counters_init(void)
 165 {
 166     shash_init(&perf_counters);
 167     perf_event_setup();
 168 }
 169
 170 void
 171 perf_counters_clear(void)
 172 {
 173     struct shash_node *node;
 174
 175     SHASH_FOR_EACH (node, &perf_counters) {
 176         struct perf_counter *perf = node->data;
 177
 178         perf->n_events = 0;
 179         perf->total_count = 0;
 180     }
 181 }
 182
 183 void
 184 perf_counters_destroy()
 185 {
 186     struct shash_node *node, *next;
 187
 188     if (fd__ != -1) {
 189         ioctl(fd__, PERF_EVENT_IOC_DISABLE, 0);
 190         close(fd__);
 191     }
 192
 193     SHASH_FOR_EACH_SAFE (node, next, &perf_counters) {
 194         shash_delete(&perf_counters, node);
 195     }
 196
 197     shash_destroy(&perf_counters);
 198 }
 199 #endif