Add a comment to clarify 941bda94
[fio.git] / steadystate.c
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1#include <stdlib.h>
2
3#include "fio.h"
4#include "steadystate.h"
5#include "helper_thread.h"
6
7bool steadystate_enabled = false;
8
9static void steadystate_alloc(struct thread_data *td)
10{
11 int i;
12
13 td->ss.bw_data = malloc(td->ss.dur * sizeof(uint64_t));
14 td->ss.iops_data = malloc(td->ss.dur * sizeof(uint64_t));
15 /* initialize so that it is obvious if the cache is not full in the output */
16 for (i = 0; i < td->ss.dur; i++)
17 td->ss.iops_data[i] = td->ss.bw_data[i] = 0;
18
19 td->ss.state |= __FIO_SS_DATA;
20}
21
22void steadystate_setup(void)
23{
24 int i, prev_groupid;
25 struct thread_data *td, *prev_td;
26
27 if (!steadystate_enabled)
28 return;
29
30 /*
31 * if group reporting is enabled, identify the last td
32 * for each group and use it for storing steady state
33 * data
34 */
35 prev_groupid = -1;
36 prev_td = NULL;
37 for_each_td(td, i) {
38 if (!td->ss.dur)
39 continue;
40
41 if (!td->o.group_reporting) {
42 steadystate_alloc(td);
43 continue;
44 }
45
46 if (prev_groupid != td->groupid) {
47 if (prev_td != NULL) {
48 steadystate_alloc(prev_td);
49 }
50 prev_groupid = td->groupid;
51 }
52 prev_td = td;
53 }
54
55 if (prev_td != NULL && prev_td->o.group_reporting) {
56 steadystate_alloc(prev_td);
57 }
58}
59
60static bool steadystate_slope(uint64_t iops, uint64_t bw,
61 struct thread_data *td)
62{
63 int i, j;
64 double result;
65 struct steadystate_data *ss = &td->ss;
66 uint64_t new_val;
67
68 ss->bw_data[ss->tail] = bw;
69 ss->iops_data[ss->tail] = iops;
70
71 if (ss->state & __FIO_SS_IOPS)
72 new_val = iops;
73 else
74 new_val = bw;
75
76 if (ss->state & __FIO_SS_BUFFER_FULL || ss->tail - ss->head == ss->dur - 1) {
77 if (!(ss->state & __FIO_SS_BUFFER_FULL)) {
78 /* first time through */
79 for(i = 0, ss->sum_y = 0; i < ss->dur; i++) {
80 if (ss->state & __FIO_SS_IOPS)
81 ss->sum_y += ss->iops_data[i];
82 else
83 ss->sum_y += ss->bw_data[i];
84 j = (ss->head + i) % ss->dur;
85 if (ss->state & __FIO_SS_IOPS)
86 ss->sum_xy += i * ss->iops_data[j];
87 else
88 ss->sum_xy += i * ss->bw_data[j];
89 }
90 ss->state |= __FIO_SS_BUFFER_FULL;
91 } else { /* easy to update the sums */
92 ss->sum_y -= ss->oldest_y;
93 ss->sum_y += new_val;
94 ss->sum_xy = ss->sum_xy - ss->sum_y + ss->dur * new_val;
95 }
96
97 if (ss->state & __FIO_SS_IOPS)
98 ss->oldest_y = ss->iops_data[ss->head];
99 else
100 ss->oldest_y = ss->bw_data[ss->head];
101
102 /*
103 * calculate slope as (sum_xy - sum_x * sum_y / n) / (sum_(x^2)
104 * - (sum_x)^2 / n) This code assumes that all x values are
105 * equally spaced when they are often off by a few milliseconds.
106 * This assumption greatly simplifies the calculations.
107 */
108 ss->slope = (ss->sum_xy - (double) ss->sum_x * ss->sum_y / ss->dur) /
109 (ss->sum_x_sq - (double) ss->sum_x * ss->sum_x / ss->dur);
110 if (ss->state & __FIO_SS_PCT)
111 ss->criterion = 100.0 * ss->slope / (ss->sum_y / ss->dur);
112 else
113 ss->criterion = ss->slope;
114
115 dprint(FD_STEADYSTATE, "sum_y: %llu, sum_xy: %llu, slope: %f, "
116 "criterion: %f, limit: %f\n",
117 (unsigned long long) ss->sum_y,
118 (unsigned long long) ss->sum_xy,
119 ss->slope, ss->criterion, ss->limit);
120
121 result = ss->criterion * (ss->criterion < 0.0 ? -1.0 : 1.0);
122 if (result < ss->limit)
123 return true;
124 }
125
126 ss->tail = (ss->tail + 1) % ss->dur;
127 if (ss->tail <= ss->head)
128 ss->head = (ss->head + 1) % ss->dur;
129
130 return false;
131}
132
133static bool steadystate_deviation(uint64_t iops, uint64_t bw,
134 struct thread_data *td)
135{
136 int i;
137 double diff;
138 double mean;
139
140 struct steadystate_data *ss = &td->ss;
141
142 ss->bw_data[ss->tail] = bw;
143 ss->iops_data[ss->tail] = iops;
144
145 if (ss->state & __FIO_SS_BUFFER_FULL || ss->tail - ss->head == ss->dur - 1) {
146 if (!(ss->state & __FIO_SS_BUFFER_FULL)) {
147 /* first time through */
148 for(i = 0, ss->sum_y = 0; i < ss->dur; i++)
149 if (ss->state & __FIO_SS_IOPS)
150 ss->sum_y += ss->iops_data[i];
151 else
152 ss->sum_y += ss->bw_data[i];
153 ss->state |= __FIO_SS_BUFFER_FULL;
154 } else { /* easy to update the sum */
155 ss->sum_y -= ss->oldest_y;
156 if (ss->state & __FIO_SS_IOPS)
157 ss->sum_y += ss->iops_data[ss->tail];
158 else
159 ss->sum_y += ss->bw_data[ss->tail];
160 }
161
162 if (ss->state & __FIO_SS_IOPS)
163 ss->oldest_y = ss->iops_data[ss->head];
164 else
165 ss->oldest_y = ss->bw_data[ss->head];
166
167 mean = (double) ss->sum_y / ss->dur;
168 ss->deviation = 0.0;
169
170 for (i = 0; i < ss->dur; i++) {
171 if (ss->state & __FIO_SS_IOPS)
172 diff = ss->iops_data[i] - mean;
173 else
174 diff = ss->bw_data[i] - mean;
175 ss->deviation = max(ss->deviation, diff * (diff < 0.0 ? -1.0 : 1.0));
176 }
177
178 if (ss->state & __FIO_SS_PCT)
179 ss->criterion = 100.0 * ss->deviation / mean;
180 else
181 ss->criterion = ss->deviation;
182
183 dprint(FD_STEADYSTATE, "sum_y: %llu, mean: %f, max diff: %f, "
184 "objective: %f, limit: %f\n",
185 (unsigned long long) ss->sum_y, mean,
186 ss->deviation, ss->criterion, ss->limit);
187
188 if (ss->criterion < ss->limit)
189 return true;
190 }
191
192 ss->tail = (ss->tail + 1) % ss->dur;
193 if (ss->tail <= ss->head)
194 ss->head = (ss->head + 1) % ss->dur;
195
196 return false;
197}
198
199void steadystate_check(void)
200{
201 int i, j, ddir, prev_groupid, group_ramp_time_over = 0;
202 unsigned long rate_time;
203 struct thread_data *td, *td2;
204 struct timeval now;
205 uint64_t group_bw = 0, group_iops = 0;
206 uint64_t td_iops, td_bytes;
207 bool ret;
208
209 prev_groupid = -1;
210 for_each_td(td, i) {
211 struct steadystate_data *ss = &td->ss;
212
213 if (!ss->dur || td->runstate <= TD_SETTING_UP ||
214 td->runstate >= TD_EXITED || !ss->state ||
215 ss->state & __FIO_SS_ATTAINED)
216 continue;
217
218 td_iops = 0;
219 td_bytes = 0;
220 if (!td->o.group_reporting ||
221 (td->o.group_reporting && td->groupid != prev_groupid)) {
222 group_bw = 0;
223 group_iops = 0;
224 group_ramp_time_over = 0;
225 }
226 prev_groupid = td->groupid;
227
228 fio_gettime(&now, NULL);
229 if (ss->ramp_time && !(ss->state & __FIO_SS_RAMP_OVER)) {
230 /*
231 * Begin recording data one second after ss->ramp_time
232 * has elapsed
233 */
234 if (utime_since(&td->epoch, &now) >= (ss->ramp_time + 1000000L))
235 ss->state |= __FIO_SS_RAMP_OVER;
236 }
237
238 td_io_u_lock(td);
239 for (ddir = DDIR_READ; ddir < DDIR_RWDIR_CNT; ddir++) {
240 td_iops += td->io_blocks[ddir];
241 td_bytes += td->io_bytes[ddir];
242 }
243 td_io_u_unlock(td);
244
245 rate_time = mtime_since(&ss->prev_time, &now);
246 memcpy(&ss->prev_time, &now, sizeof(now));
247
248 /*
249 * Begin monitoring when job starts but don't actually use
250 * data in checking stopping criterion until ss->ramp_time is
251 * over. This ensures that we will have a sane value in
252 * prev_iops/bw the first time through after ss->ramp_time
253 * is done.
254 */
255 if (ss->state & __FIO_SS_RAMP_OVER) {
256 group_bw += 1000 * (td_bytes - ss->prev_bytes) / rate_time;
257 group_iops += 1000 * (td_iops - ss->prev_iops) / rate_time;
258 ++group_ramp_time_over;
259 }
260 ss->prev_iops = td_iops;
261 ss->prev_bytes = td_bytes;
262
263 if (td->o.group_reporting && !(ss->state & __FIO_SS_DATA))
264 continue;
265
266 /*
267 * Don't begin checking criterion until ss->ramp_time is over
268 * for at least one thread in group
269 */
270 if (!group_ramp_time_over)
271 continue;
272
273 dprint(FD_STEADYSTATE, "steadystate_check() thread: %d, "
274 "groupid: %u, rate_msec: %ld, "
275 "iops: %llu, bw: %llu, head: %d, tail: %d\n",
276 i, td->groupid, rate_time,
277 (unsigned long long) group_iops,
278 (unsigned long long) group_bw,
279 ss->head, ss->tail);
280
281 if (ss->state & __FIO_SS_SLOPE)
282 ret = steadystate_slope(group_iops, group_bw, td);
283 else
284 ret = steadystate_deviation(group_iops, group_bw, td);
285
286 if (ret) {
287 if (td->o.group_reporting) {
288 for_each_td(td2, j) {
289 if (td2->groupid == td->groupid) {
290 td2->ss.state |= __FIO_SS_ATTAINED;
291 fio_mark_td_terminate(td2);
292 }
293 }
294 } else {
295 ss->state |= __FIO_SS_ATTAINED;
296 fio_mark_td_terminate(td);
297 }
298 }
299 }
300}
301
302int td_steadystate_init(struct thread_data *td)
303{
304 struct steadystate_data *ss = &td->ss;
305 struct thread_options *o = &td->o;
306 struct thread_data *td2;
307 int j;
308
309 memset(ss, 0, sizeof(*ss));
310
311 if (o->ss_dur) {
312 steadystate_enabled = true;
313 o->ss_dur /= 1000000L;
314
315 /* put all steady state info in one place */
316 ss->dur = o->ss_dur;
317 ss->limit = o->ss_limit.u.f;
318 ss->ramp_time = o->ss_ramp_time;
319
320 ss->state = o->ss_state;
321 if (!td->ss.ramp_time)
322 ss->state |= __FIO_SS_RAMP_OVER;
323
324 ss->sum_x = o->ss_dur * (o->ss_dur - 1) / 2;
325 ss->sum_x_sq = (o->ss_dur - 1) * (o->ss_dur) * (2*o->ss_dur - 1) / 6;
326 }
327
328 /* make sure that ss options are consistent within reporting group */
329 for_each_td(td2, j) {
330 if (td2->groupid == td->groupid) {
331 struct steadystate_data *ss2 = &td2->ss;
332
333 if (ss2->dur != ss->dur ||
334 ss2->limit != ss->limit ||
335 ss2->ramp_time != ss->ramp_time ||
336 ss2->state != ss->state ||
337 ss2->sum_x != ss->sum_x ||
338 ss2->sum_x_sq != ss->sum_x_sq) {
339 td_verror(td, EINVAL, "job rejected: steadystate options must be consistent within reporting groups");
340 return 1;
341 }
342 }
343 }
344
345 return 0;
346}
347
348uint64_t steadystate_bw_mean(struct thread_stat *ts)
349{
350 int i;
351 uint64_t sum;
352
353 for (i = 0, sum = 0; i < ts->ss_dur; i++)
354 sum += ts->ss_bw_data[i];
355
356 return sum / ts->ss_dur;
357}
358
359uint64_t steadystate_iops_mean(struct thread_stat *ts)
360{
361 int i;
362 uint64_t sum;
363
364 for (i = 0, sum = 0; i < ts->ss_dur; i++)
365 sum += ts->ss_iops_data[i];
366
367 return sum / ts->ss_dur;
368}