1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
#ifdef CONFIG_LITMUS_NVIDIA
#include <linux/sched.h>
#include <litmus/litmus.h>
#include <litmus/gpu_affinity.h>
#include <litmus/sched_trace.h>
#define OBSERVATION_CAP ((lt_t)(2e9))
// reason for skew: high outliers are less
// frequent and way out of bounds
//#define HI_THRESHOLD 2
//#define LO_THRESHOLD 4
#define NUM_STDEV_NUM 1
#define NUM_STDEV_DENOM 2
#define MIN(a, b) ((a < b) ? a : b)
#if 0
/* PID feedback controller */
static fp_t update_estimate(feedback_est_t* fb, fp_t a, fp_t b, lt_t observed)
{
fp_t relative_err;
fp_t err, new;
fp_t actual = _integer_to_fp(observed);
err = _sub(actual, fb->est);
new = _add(_mul(a, err), _mul(b, fb->accum_err));
relative_err = _div(err, actual);
fb->est = new;
fb->accum_err = _add(fb->accum_err, err);
return relative_err;
}
#endif
static lt_t varience(lt_t nums[], const lt_t avg, const uint16_t count)
{
/* brute force: takes about as much time as incremental running methods when
* count < 50 (on Bonham). Brute force also less prone to overflow.
*/
lt_t sqdeviations = 0;
uint16_t i;
for(i = 0; i < count; ++i)
{
lt_t temp = (int64_t)nums[i] - (int64_t)avg;
sqdeviations += temp * temp;
}
return sqdeviations/count;
}
static lt_t isqrt(lt_t n)
{
/* integer square root using babylonian method
* (algo taken from wikipedia */
lt_t res = 0;
lt_t bit = ((lt_t)1) << (sizeof(n)*8-2);
while (bit > n) {
bit >>= 2;
}
while (bit != 0) {
if (n >= res + bit) {
n -= res + bit;
res = (res >> 1) + bit;
}
else {
res >>= 1;
}
bit >>= 2;
}
return res;
}
void update_gpu_estimate(struct task_struct *t, lt_t observed)
{
avg_est_t *est;
BUG_ON(tsk_rt(t)->gpu_migration > MIG_LAST);
est = &(tsk_rt(t)->gpu_migration_est[tsk_rt(t)->gpu_migration]);
{
/* log the migration event */
struct migration_info mig_info;
mig_info.observed = observed;
mig_info.estimated = est->avg;
mig_info.distance = tsk_rt(t)->gpu_migration;
sched_trace_migration(t, &mig_info);
}
if (unlikely(observed > OBSERVATION_CAP)) {
TRACE_TASK(t, "Crazy observation greater than was dropped: %llu > %llu\n",
observed,
OBSERVATION_CAP);
return;
}
// filter values outside NUM_STDEVx the standard deviation,
// but only filter if enough samples have been taken.
if (likely((est->count > MIN(10, AVG_EST_WINDOW_SIZE/2)))) {
lt_t lower, upper;
lt_t range = (est->std*NUM_STDEV_NUM)/NUM_STDEV_DENOM;
lower = est->avg - MIN(range, est->avg); // no underflow.
if (unlikely(observed < lower)) {
TRACE_TASK(t, "Observation is too small: %llu\n", observed);
return;
}
upper = est->avg + range;
if (unlikely(observed > upper)) {
TRACE_TASK(t, "Observation is too large: %llu\n", observed);
return;
}
}
if (unlikely(est->count < AVG_EST_WINDOW_SIZE)) {
++est->count;
}
else {
est->sum -= est->history[est->idx];
}
est->history[est->idx] = observed;
est->sum += observed;
est->avg = est->sum/est->count;
est->std = isqrt(varience(est->history, est->avg, est->count));
est->idx = (est->idx + 1) % AVG_EST_WINDOW_SIZE;
TRACE_TASK(t, "GPU est update after (dist = %d, obs = %llu): %llu\n",
tsk_rt(t)->gpu_migration,
observed,
est->avg);
}
gpu_migration_dist_t gpu_migration_distance(int a, int b)
{
// GPUs organized in a binary hierarchy, no more than 2^MIG_FAR GPUs
int i;
int dist;
if(likely(a >= 0 && b >= 0)) {
for(i = 0; i <= MIG_FAR; ++i) {
if(a>>i == b>>i) {
dist = i;
goto out;
}
}
dist = MIG_NONE; // hopefully never reached.
TRACE_CUR("WARNING: GPU distance too far! %d -> %d\n", a, b);
}
else {
dist = MIG_NONE;
}
out:
TRACE_CUR("Distance %d -> %d is %d\n",
a, b, dist);
return dist;
}
#endif
|
