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b0c3cf94 CF |
1 | /* |
2 | * QEMU System Emulator | |
3 | * | |
4 | * Copyright (c) 2003-2008 Fabrice Bellard | |
5 | * | |
6 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
7 | * of this software and associated documentation files (the "Software"), to deal | |
8 | * in the Software without restriction, including without limitation the rights | |
9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
10 | * copies of the Software, and to permit persons to whom the Software is | |
11 | * furnished to do so, subject to the following conditions: | |
12 | * | |
13 | * The above copyright notice and this permission notice shall be included in | |
14 | * all copies or substantial portions of the Software. | |
15 | * | |
16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
22 | * THE SOFTWARE. | |
23 | */ | |
24 | ||
25 | #include "qemu/osdep.h" | |
b0c3cf94 CF |
26 | #include "qemu/thread.h" |
27 | #include "hw/core/cpu.h" | |
28 | #include "qemu/main-loop.h" | |
29 | #include "sysemu/cpus.h" | |
30 | #include "sysemu/cpu-throttle.h" | |
31 | ||
32 | /* vcpu throttling controls */ | |
33 | static QEMUTimer *throttle_timer; | |
34 | static unsigned int throttle_percentage; | |
35 | ||
36 | #define CPU_THROTTLE_PCT_MIN 1 | |
37 | #define CPU_THROTTLE_PCT_MAX 99 | |
38 | #define CPU_THROTTLE_TIMESLICE_NS 10000000 | |
39 | ||
40 | static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque) | |
41 | { | |
42 | double pct; | |
43 | double throttle_ratio; | |
44 | int64_t sleeptime_ns, endtime_ns; | |
45 | ||
46 | if (!cpu_throttle_get_percentage()) { | |
47 | return; | |
48 | } | |
49 | ||
50 | pct = (double)cpu_throttle_get_percentage() / 100; | |
51 | throttle_ratio = pct / (1 - pct); | |
52 | /* Add 1ns to fix double's rounding error (like 0.9999999...) */ | |
53 | sleeptime_ns = (int64_t)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS + 1); | |
54 | endtime_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + sleeptime_ns; | |
55 | while (sleeptime_ns > 0 && !cpu->stop) { | |
56 | if (sleeptime_ns > SCALE_MS) { | |
57 | qemu_cond_timedwait_iothread(cpu->halt_cond, | |
58 | sleeptime_ns / SCALE_MS); | |
59 | } else { | |
60 | qemu_mutex_unlock_iothread(); | |
61 | g_usleep(sleeptime_ns / SCALE_US); | |
62 | qemu_mutex_lock_iothread(); | |
63 | } | |
64 | sleeptime_ns = endtime_ns - qemu_clock_get_ns(QEMU_CLOCK_REALTIME); | |
65 | } | |
d73415a3 | 66 | qatomic_set(&cpu->throttle_thread_scheduled, 0); |
b0c3cf94 CF |
67 | } |
68 | ||
69 | static void cpu_throttle_timer_tick(void *opaque) | |
70 | { | |
71 | CPUState *cpu; | |
72 | double pct; | |
73 | ||
74 | /* Stop the timer if needed */ | |
75 | if (!cpu_throttle_get_percentage()) { | |
76 | return; | |
77 | } | |
78 | CPU_FOREACH(cpu) { | |
d73415a3 | 79 | if (!qatomic_xchg(&cpu->throttle_thread_scheduled, 1)) { |
b0c3cf94 CF |
80 | async_run_on_cpu(cpu, cpu_throttle_thread, |
81 | RUN_ON_CPU_NULL); | |
82 | } | |
83 | } | |
84 | ||
85 | pct = (double)cpu_throttle_get_percentage() / 100; | |
86 | timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) + | |
87 | CPU_THROTTLE_TIMESLICE_NS / (1 - pct)); | |
88 | } | |
89 | ||
90 | void cpu_throttle_set(int new_throttle_pct) | |
91 | { | |
33c38f8c UT |
92 | /* |
93 | * boolean to store whether throttle is already active or not, | |
94 | * before modifying throttle_percentage | |
95 | */ | |
96 | bool throttle_active = cpu_throttle_active(); | |
97 | ||
b0c3cf94 CF |
98 | /* Ensure throttle percentage is within valid range */ |
99 | new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX); | |
100 | new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN); | |
101 | ||
d73415a3 | 102 | qatomic_set(&throttle_percentage, new_throttle_pct); |
b0c3cf94 | 103 | |
33c38f8c UT |
104 | if (!throttle_active) { |
105 | cpu_throttle_timer_tick(NULL); | |
106 | } | |
b0c3cf94 CF |
107 | } |
108 | ||
109 | void cpu_throttle_stop(void) | |
110 | { | |
d73415a3 | 111 | qatomic_set(&throttle_percentage, 0); |
b0c3cf94 CF |
112 | } |
113 | ||
114 | bool cpu_throttle_active(void) | |
115 | { | |
116 | return (cpu_throttle_get_percentage() != 0); | |
117 | } | |
118 | ||
119 | int cpu_throttle_get_percentage(void) | |
120 | { | |
d73415a3 | 121 | return qatomic_read(&throttle_percentage); |
b0c3cf94 CF |
122 | } |
123 | ||
124 | void cpu_throttle_init(void) | |
125 | { | |
126 | throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT, | |
127 | cpu_throttle_timer_tick, NULL); | |
128 | } |