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
176
177
178
179
180
181
|
/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <stddef.h>
#include <errno.h>
#include <signal.h>
#include <time.h>
#include <sys/time.h>
#include "kern_constants.h"
#include "kern_util.h"
#include "os.h"
#include "process.h"
#include "user.h"
int set_interval(void)
{
int usec = UM_USEC_PER_SEC / UM_HZ;
struct itimerval interval = ((struct itimerval) { { 0, usec },
{ 0, usec } });
if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
return -errno;
return 0;
}
int timer_one_shot(int ticks)
{
unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
unsigned long sec = usec / UM_USEC_PER_SEC;
struct itimerval interval;
usec %= UM_USEC_PER_SEC;
interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
return -errno;
return 0;
}
/**
* timeval_to_ns - Convert timeval to nanoseconds
* @ts: pointer to the timeval variable to be converted
*
* Returns the scalar nanosecond representation of the timeval
* parameter.
*
* Ripped from linux/time.h because it's a kernel header, and thus
* unusable from here.
*/
static inline long long timeval_to_ns(const struct timeval *tv)
{
return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
tv->tv_usec * UM_NSEC_PER_USEC;
}
long long disable_timer(void)
{
struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
int remain, max = UM_NSEC_PER_SEC / UM_HZ;
if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
printk(UM_KERN_ERR "disable_timer - setitimer failed, "
"errno = %d\n", errno);
remain = timeval_to_ns(&time.it_value);
if (remain > max)
remain = max;
return remain;
}
long long os_nsecs(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return timeval_to_ns(&tv);
}
#ifdef UML_CONFIG_NO_HZ
static int after_sleep_interval(struct timespec *ts)
{
return 0;
}
static void deliver_alarm(void)
{
alarm_handler(SIGVTALRM, NULL);
}
static unsigned long long sleep_time(unsigned long long nsecs)
{
return nsecs;
}
#else
unsigned long long last_tick;
unsigned long long skew;
static void deliver_alarm(void)
{
unsigned long long this_tick = os_nsecs();
int one_tick = UM_NSEC_PER_SEC / UM_HZ;
if (last_tick == 0)
last_tick = this_tick - one_tick;
skew += this_tick - last_tick;
while (skew >= one_tick) {
alarm_handler(SIGVTALRM, NULL);
skew -= one_tick;
}
last_tick = this_tick;
}
static unsigned long long sleep_time(unsigned long long nsecs)
{
return nsecs > skew ? nsecs - skew : 0;
}
static inline long long timespec_to_us(const struct timespec *ts)
{
return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
ts->tv_nsec / UM_NSEC_PER_USEC;
}
static int after_sleep_interval(struct timespec *ts)
{
int usec = UM_USEC_PER_SEC / UM_HZ;
long long start_usecs = timespec_to_us(ts);
struct timeval tv;
struct itimerval interval;
/*
* It seems that rounding can increase the value returned from
* setitimer to larger than the one passed in. Over time,
* this will cause the remaining time to be greater than the
* tick interval. If this happens, then just reduce the first
* tick to the interval value.
*/
if (start_usecs > usec)
start_usecs = usec;
start_usecs -= skew / UM_NSEC_PER_USEC;
tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC,
.tv_usec = start_usecs % UM_USEC_PER_SEC });
interval = ((struct itimerval) { { 0, usec }, tv });
if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
return -errno;
return 0;
}
#endif
void idle_sleep(unsigned long long nsecs)
{
struct timespec ts;
/*
* nsecs can come in as zero, in which case, this starts a
* busy loop. To prevent this, reset nsecs to the tick
* interval if it is zero.
*/
if (nsecs == 0)
nsecs = UM_NSEC_PER_SEC / UM_HZ;
nsecs = sleep_time(nsecs);
ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC,
.tv_nsec = nsecs % UM_NSEC_PER_SEC });
if (nanosleep(&ts, &ts) == 0)
deliver_alarm();
after_sleep_interval(&ts);
}
|
