steadystate.c

   1 #include <stdlib.h>
   2
   3 #include "fio.h"
   4 #include "steadystate.h"
   5 #include "helper_thread.h"
   6
   7 void steadystate_setup()
   8 {
   9         int i, prev_groupid;
  10         struct thread_data *td, *prev_td;
  11
  12         if (!steadystate)
  13                 return;
  14
  15         /*
  16          * if group reporting is enabled, identify the last td
  17          * for each group and use it for storing steady state
  18          * data
  19          */
  20         prev_groupid = -1;
  21         prev_td = NULL;
  22         for_each_td(td, i) {
  23                 if (td->ts.ss == NULL)
  24                         continue;
  25
  26                 if (!td->o.group_reporting) {
  27                         steadystate_alloc(td);
  28                         continue;
  29                 }
  30
  31                 if (prev_groupid != td->groupid) {
  32                         if (prev_td != NULL) {
  33                                 prev_td->ss.last_in_group = 1;
  34                                 steadystate_alloc(prev_td);
  35                         }
  36                         prev_groupid = td->groupid;
  37                 }
  38                 prev_td = td;
  39         }
  40
  41         if (prev_td != NULL && prev_td->o.group_reporting) {
  42                 prev_td->ss.last_in_group = 1;
  43                 steadystate_alloc(prev_td);
  44         }
  45 }
  46
  47 void steadystate_alloc(struct thread_data *td)
  48 {
  49         int i;
  50
  51         td->ss.bw_data = malloc(td->ss.dur * sizeof(unsigned long));
  52         td->ss.iops_data = malloc(td->ss.dur * sizeof(unsigned long));
  53         /* initialize so that it is obvious if the cache is not full in the output */
  54         for (i = 0; i < td->ss.dur; i++)
  55                 td->ss.iops_data[i] = td->ss.bw_data[i] = 0;
  56 }
  57
  58 void steadystate_check()
  59 {
  60         int i, j, ddir, prev_groupid, group_ramp_time_over = 0;
  61         unsigned long rate_time;
  62         struct thread_data *td, *td2;
  63         struct timeval now;
  64         unsigned long group_bw = 0, group_iops = 0;
  65         unsigned long long td_iops;
  66         unsigned long long td_bytes;
  67
  68         prev_groupid = -1;
  69         for_each_td(td, i) {
  70                 struct steadystate_data *ss = &td->ss;
  71
  72                 if (!ss->dur || td->runstate <= TD_SETTING_UP || td->runstate >= TD_EXITED || ss->attained)
  73                         continue;
  74
  75                 td_iops = 0;
  76                 td_bytes = 0;
  77                 if (!td->o.group_reporting ||
  78                     (td->o.group_reporting && td->groupid != prev_groupid)) {
  79                         group_bw = 0;
  80                         group_iops = 0;
  81                         group_ramp_time_over = 0;
  82                 }
  83                 prev_groupid = td->groupid;
  84
  85                 fio_gettime(&now, NULL);
  86                 if (ss->ramp_time && !ss->ramp_time_over)
  87                         /*
  88                          * Begin recording data one second after ss->ramp_time
  89                          * has elapsed
  90                          */
  91                         if (utime_since(&td->epoch, &now) >= (ss->ramp_time + 1000000L))
  92                                 ss->ramp_time_over = 1;
  93
  94                 td_io_u_lock(td);
  95                 for (ddir = DDIR_READ; ddir < DDIR_RWDIR_CNT; ddir++) {
  96                         td_iops += td->io_blocks[ddir];
  97                         td_bytes += td->io_bytes[ddir];
  98                 }
  99                 td_io_u_unlock(td);
 100
 101                 rate_time = mtime_since(&ss->prev_time, &now);
 102                 memcpy(&ss->prev_time, &now, sizeof(now));
 103
 104                 /*
 105                  * Begin monitoring when job starts but don't actually use
 106                  * data in checking stopping criterion until ss->ramp_time is
 107                  * over. This ensures that we will have a sane value in
 108                  * prev_iops/bw the first time through after ss->ramp_time
 109                  * is done.
 110                  */
 111                 if (ss->ramp_time_over) {
 112                         group_bw += 1000 * (td_bytes - ss->prev_bytes) / rate_time;
 113                         group_iops += 1000 * (td_iops - ss->prev_iops) / rate_time;
 114                         ++group_ramp_time_over;
 115                 }
 116                 ss->prev_iops = td_iops;
 117                 ss->prev_bytes = td_bytes;
 118
 119                 if (td->o.group_reporting && !ss->last_in_group)
 120                         continue;
 121
 122                 /* don't begin checking criterion until ss->ramp_time is over for at least one thread in group */
 123                 if (!group_ramp_time_over)
 124                         continue;
 125
 126                 dprint(FD_STEADYSTATE, "steadystate_check() thread: %d, groupid: %u, rate_msec: %ld, iops: %lu, bw: %lu, head: %d, tail: %d\n",
 127                         i, td->groupid, rate_time, group_iops, group_bw, ss->head, ss->tail);
 128
 129                 if (ss->evaluate(group_iops, group_bw, td))
 130                 {
 131                         if (td->o.group_reporting)
 132                                 for_each_td(td2, j) {
 133                                         if (td2->groupid == td->groupid) {
 134                                                 td2->ss.attained = 1;
 135                                                 fio_mark_td_terminate(td2);
 136                                         }
 137                                 }
 138                         else {
 139                                 ss->attained = 1;
 140                                 fio_mark_td_terminate(td);
 141                         }
 142                 }
 143         }
 144 }
 145
 146 bool steadystate_slope(unsigned long iops, unsigned long bw, struct thread_data *td)
 147 {
 148         int i, j;
 149         double result;
 150         struct steadystate_data *ss = &td->ss;
 151         unsigned long new_val = ss->check_iops ? iops : bw;
 152
 153         ss->bw_data[ss->tail] = bw;
 154         ss->iops_data[ss->tail] = iops;
 155
 156         if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1))
 157         {
 158                 if (ss->sum_y == 0)     /* first time through */
 159                 {
 160                         for(i = 0; i < ss->dur; i++)
 161                         {
 162                                 ss->sum_y += ss->check_iops ? ss->iops_data[i] : ss->bw_data[i];
 163                                 j = ss->head + i;
 164                                 if (j >= ss->dur)
 165                                         j -= ss->dur;
 166                                 ss->sum_xy += (ss->check_iops ? ss->iops_data[j] : ss->bw_data[j]) * i;
 167                         }
 168                 } else {                /* easy to update the sums */
 169                         ss->sum_y -= ss->oldest_y;
 170                         ss->sum_y += new_val;
 171                         ss->sum_xy = ss->sum_xy - ss->sum_y + ss->dur * new_val;
 172                 }
 173
 174                 ss->oldest_y = ss->check_iops ? ss->iops_data[ss->head] : ss->bw_data[ss->head];
 175
 176                 /*
 177                  * calculate slope as (sum_xy - sum_x * sum_y / n) / (sum_(x^2) - (sum_x)^2 / n)
 178                  * This code assumes that all x values are equally spaced when they are often
 179                  * off by a few milliseconds. This assumption greatly simplifies the
 180                  * calculations.
 181                  */
 182                 ss->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);
 183                 ss->criterion = ss->pct ? 100.0 * ss->slope / (ss->sum_y / ss->dur) : ss->slope;
 184
 185                 dprint(FD_STEADYSTATE, "sum_y: %llu, sum_xy: %llu, slope: %f, criterion: %f, limit: %f\n",
 186                         ss->sum_y, ss->sum_xy, ss->slope, ss->criterion, ss->limit);
 187
 188                 result = ss->criterion * (ss->criterion < 0.0 ? -1.0 : 1.0);
 189                 if (result < ss->limit)
 190                         return true;
 191         }
 192
 193         ss->tail = (ss->tail + 1) % ss->dur;
 194         if (ss->tail <= ss->head)
 195                 ss->head = (ss->head + 1) % ss->dur;
 196         return false;
 197 }
 198
 199 bool steadystate_deviation(unsigned long iops, unsigned long bw, struct thread_data *td)
 200 {
 201         int i;
 202         double diff;
 203         double mean;
 204
 205         struct steadystate_data *ss = &td->ss;
 206
 207         ss->bw_data[ss->tail] = bw;
 208         ss->iops_data[ss->tail] = iops;
 209
 210         if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1))
 211         {
 212                 if (ss->sum_y == 0)     /* first time through */
 213                 {
 214                         for(i = 0; i < ss->dur; i++)
 215                                 ss->sum_y += ss->check_iops ? ss->iops_data[i] : ss->bw_data[i];
 216                 } else {                /* easy to update the sum */
 217                         ss->sum_y -= ss->oldest_y;
 218                         ss->sum_y += ss->check_iops ? ss->iops_data[ss->tail] : ss->bw_data[ss->tail];
 219                 }
 220
 221                 ss->oldest_y = ss->check_iops ? ss->iops_data[ss->head] : ss->bw_data[ss->head];
 222                 mean = (double) ss->sum_y / ss->dur;
 223                 ss->deviation = 0.0;
 224
 225                 for (i = 0; i < ss->dur; i++)
 226                 {
 227                         diff = (double) (ss->check_iops ? ss->iops_data[i] : ss->bw_data[i]) - mean;
 228                         ss->deviation = max(ss->deviation, diff * (diff < 0.0 ? -1.0 : 1.0));
 229                 }
 230
 231                 ss->criterion = ss->pct ? 100.0 * ss->deviation / mean : ss->deviation;
 232
 233                 dprint(FD_STEADYSTATE, "sum_y: %llu, mean: %f, max diff: %f, objective: %f, limit: %f\n", ss->sum_y, mean, ss->deviation, ss->criterion, ss->limit);
 234
 235                 if (ss->criterion < ss->limit)
 236                         return true;
 237         }
 238
 239         ss->tail = (ss->tail + 1) % ss->dur;
 240         if (ss->tail <= ss->head)
 241                 ss->head = (ss->head + 1) % ss->dur;
 242         return false;
 243 }