steadystate.c

   1 #include "fio.h"
   2 #include "steadystate.h"
   3 #include "helper_thread.h"
   4
   5 void steadystate_setup()
   6 {
   7         int i, prev_groupid;
   8         struct thread_data *td, *prev_td;
   9
  10         if (!steadystate)
  11                 return;
  12
  13         /*
  14          * if group reporting is enabled, identify the last td
  15          * for each group and use it for storing steady state
  16          * data
  17          */
  18         prev_groupid = -1;
  19         prev_td = NULL;
  20         for_each_td(td, i) {
  21                 if (!td->o.group_reporting)
  22                         continue;
  23
  24                 if (prev_groupid != td->groupid) {
  25                         if (prev_td != NULL)
  26                                 prev_td->ss.last_in_group = 1;
  27                         prev_groupid = td->groupid;
  28                 }
  29                 prev_td = td;
  30         }
  31
  32         if (prev_td != NULL && prev_td->o.group_reporting)
  33                 prev_td->ss.last_in_group = 1;
  34 }
  35
  36 void steadystate_check()
  37 {
  38         int i, j, ddir, prev_groupid, group_ramp_time_over = 0;
  39         unsigned long rate_time;
  40         struct thread_data *td, *td2;
  41         struct timeval now;
  42         unsigned long group_bw = 0, group_iops = 0;
  43         unsigned long long td_iops;
  44         unsigned long long td_bytes;
  45
  46         prev_groupid = -1;
  47         for_each_td(td, i) {
  48                 struct steadystate_data *ss = &td->ss;
  49
  50                 if (!ss->dur || td->runstate <= TD_SETTING_UP || td->runstate >= TD_EXITED || ss->attained)
  51                         continue;
  52
  53                 td_iops = 0;
  54                 td_bytes = 0;
  55                 if (!td->o.group_reporting ||
  56                     (td->o.group_reporting && td->groupid != prev_groupid)) {
  57                         group_bw = 0;
  58                         group_iops = 0;
  59                         group_ramp_time_over = 0;
  60                 }
  61                 prev_groupid = td->groupid;
  62
  63                 fio_gettime(&now, NULL);
  64                 if (ss->ramp_time && !ss->ramp_time_over)
  65                         /*
  66                          * Begin recording data one second after ss->ramp_time
  67                          * has elapsed
  68                          */
  69                         if (utime_since(&td->epoch, &now) >= (ss->ramp_time + 1000000L))
  70                                 ss->ramp_time_over = 1;
  71
  72                 for (ddir = DDIR_READ; ddir < DDIR_RWDIR_CNT; ddir++) {
  73                         td_iops += td->io_blocks[ddir];
  74                         td_bytes += td->io_bytes[ddir];
  75                 }
  76
  77                 rate_time = mtime_since(&ss->prev_time, &now);
  78                 memcpy(&ss->prev_time, &now, sizeof(now));
  79
  80                 /*
  81                  * Begin monitoring when job starts but don't actually use
  82                  * data in checking stopping criterion until ss->ramp_time is
  83                  * over. This ensures that we will have a sane value in
  84                  * prev_iops/bw the first time through after ss->ramp_time
  85                  * is done.
  86                  */
  87                 if (ss->ramp_time_over) {
  88                         group_bw += 1000 * (td_bytes - ss->prev_bytes) / rate_time;
  89                         group_iops += 1000 * (td_iops - ss->prev_iops) / rate_time;
  90                         ++group_ramp_time_over;
  91                 }
  92                 ss->prev_iops = td_iops;
  93                 ss->prev_bytes = td_bytes;
  94
  95                 if (td->o.group_reporting && !ss->last_in_group)
  96                         continue;
  97
  98                 /* don't begin checking criterion until ss->ramp_time is over for at least one thread in group */
  99                 if (!group_ramp_time_over)
 100                         continue;
 101
 102                 dprint(FD_STEADYSTATE, "steadystate_check() thread: %d, groupid: %u, rate_msec: %ld, iops: %lu, bw: %lu, head: %d, tail: %d\n",
 103                         i, td->groupid, rate_time, group_iops, group_bw, ss->head, ss->tail);
 104
 105                 if (ss->evaluate(group_iops, group_bw, td))
 106                 {
 107                         if (td->o.group_reporting)
 108                                 for_each_td(td2, j) {
 109                                         if (td2->groupid == td->groupid) {
 110                                                 td2->ss.attained = 1;
 111                                                 fio_mark_td_terminate(td2);
 112                                         }
 113                                 }
 114                         else {
 115                                 ss->attained = 1;
 116                                 fio_mark_td_terminate(td);
 117                         }
 118                 }
 119         }
 120 }
 121
 122 bool steadystate_slope(unsigned long iops, unsigned long bw, struct thread_data *td)
 123 {
 124         int i, x;
 125         double result;
 126         double slope;
 127         struct steadystate_data *ss = &td->ss;
 128
 129         ss->cache[ss->tail] = ss->check_iops ? iops : bw;
 130
 131         if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1))
 132         {
 133                 if (ss->sum_y == 0)     /* first time through */
 134                 {
 135                         for(i = 0; i < ss->dur; i++)
 136                         {
 137                                 ss->sum_y += ss->cache[i];
 138                                 x = ss->head + i;
 139                                 if (x >= ss->dur)
 140                                         x -= ss->dur;
 141                                 ss->sum_xy += ss->cache[x] * i;
 142                         }
 143                 } else {                /* easy to update the sums */
 144                         ss->sum_y -= ss->oldest_y;
 145                         ss->sum_y += ss->cache[ss->tail];
 146                         ss->sum_xy = ss->sum_xy - ss->sum_y + ss->dur * ss->cache[ss->tail];
 147                 }
 148
 149                 ss->oldest_y = ss->cache[ss->head];
 150
 151                 /*
 152                  * calculate slope as (sum_xy - sum_x * sum_y / n) / (sum_(x^2) - (sum_x)^2 / n)
 153                  * This code assumes that all x values are equally spaced when they are often
 154                  * off by a few milliseconds. This assumption greatly simplifies the
 155                  * calculations.
 156                  */
 157                 slope = (ss->sum_xy - (double) ss->sum_x * ss->sum_y / ss->dur) / (ss->sum_x_sq - (double) ss->sum_x * ss->sum_x / ss->dur);
 158                 ss->criterion = ss->pct ? slope / (ss->sum_y / ss->dur) * 100.0: slope;
 159
 160                 dprint(FD_STEADYSTATE, "sum_y: %llu, sum_xy: %llu, slope: %f, criterion: %f, limit: %f\n",
 161                         ss->sum_y, ss->sum_xy, slope, ss->criterion, ss->limit);
 162
 163                 result = ss->criterion * (ss->criterion < 0.0 ? -1 : 1);
 164                 if (result < ss->limit)
 165                         return true;
 166         }
 167
 168         ss->tail = (ss->tail + 1) % ss->dur;
 169         if (ss->tail <= ss->head)
 170                 ss->head = (ss->head + 1) % ss->dur;
 171         return false;
 172 }
 173
 174 bool steadystate_deviation(unsigned long iops, unsigned long bw, struct thread_data *td)
 175 {
 176         int i;
 177         double diff;
 178         double mean;
 179         double deviation;
 180
 181         struct steadystate_data *ss = &td->ss;
 182
 183         ss->cache[ss->tail] = ss->check_iops ? iops : bw;
 184
 185         if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1))
 186         {
 187                 if (ss->sum_y == 0)     /* first time through */
 188                 {
 189                         for(i = 0; i < ss->dur; i++)
 190                                 ss->sum_y += ss->cache[i];
 191                 } else {                /* easy to update the sum */
 192                         ss->sum_y -= ss->oldest_y;
 193                         ss->sum_y += ss->cache[ss->tail];
 194                 }
 195
 196                 ss->oldest_y = ss->cache[ss->head];
 197                 mean = (double) ss->sum_y / ss->dur;
 198                 deviation = 0.0;
 199
 200                 for (i = 0; i < ss->dur; i++)
 201                 {
 202                         diff = (double) ss->cache[i] - mean;
 203                         deviation = max(deviation, diff * (diff < 0.0 ? -1 : 1));
 204                 }
 205
 206                 ss->criterion = ss->pct ? deviation / mean * 100.0 : deviation;
 207
 208                 dprint(FD_STEADYSTATE, "sum_y: %llu, mean: %f, max diff: %f, objective: %f, limit: %f\n", ss->sum_y, mean, deviation, ss->criterion, ss->limit);
 209
 210                 if (ss->criterion < ss->limit)
 211                         return true;
 212         }
 213
 214         ss->tail = (ss->tail + 1) % ss->dur;
 215         if (ss->tail <= ss->head)
 216                 ss->head = (ss->head + 1) % ss->dur;
 217         return false;
 218 }