diff options
Diffstat (limited to 'cpus.c')
| -rw-r--r-- | cpus.c | 78 |
1 files changed, 78 insertions, 0 deletions
@@ -69,6 +69,14 @@ static CPUState *next_cpu; int64_t max_delay; int64_t max_advance; +/* vcpu throttling controls */ +static QEMUTimer *throttle_timer; +static unsigned int throttle_percentage; + +#define CPU_THROTTLE_PCT_MIN 1 +#define CPU_THROTTLE_PCT_MAX 99 +#define CPU_THROTTLE_TIMESLICE_NS 10000000 + bool cpu_is_stopped(CPUState *cpu) { return cpu->stopped || !runstate_is_running(); @@ -505,10 +513,80 @@ static const VMStateDescription vmstate_timers = { } }; +static void cpu_throttle_thread(void *opaque) +{ + CPUState *cpu = opaque; + double pct; + double throttle_ratio; + long sleeptime_ns; + + if (!cpu_throttle_get_percentage()) { + return; + } + + pct = (double)cpu_throttle_get_percentage()/100; + throttle_ratio = pct / (1 - pct); + sleeptime_ns = (long)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS); + + qemu_mutex_unlock_iothread(); + atomic_set(&cpu->throttle_thread_scheduled, 0); + g_usleep(sleeptime_ns / 1000); /* Convert ns to us for usleep call */ + qemu_mutex_lock_iothread(); +} + +static void cpu_throttle_timer_tick(void *opaque) +{ + CPUState *cpu; + double pct; + + /* Stop the timer if needed */ + if (!cpu_throttle_get_percentage()) { + return; + } + CPU_FOREACH(cpu) { + if (!atomic_xchg(&cpu->throttle_thread_scheduled, 1)) { + async_run_on_cpu(cpu, cpu_throttle_thread, cpu); + } + } + + pct = (double)cpu_throttle_get_percentage()/100; + timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE_NS / (1-pct)); +} + +void cpu_throttle_set(int new_throttle_pct) +{ + /* Ensure throttle percentage is within valid range */ + new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX); + new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN); + + atomic_set(&throttle_percentage, new_throttle_pct); + + timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE_NS); +} + +void cpu_throttle_stop(void) +{ + atomic_set(&throttle_percentage, 0); +} + +bool cpu_throttle_active(void) +{ + return (cpu_throttle_get_percentage() != 0); +} + +int cpu_throttle_get_percentage(void) +{ + return atomic_read(&throttle_percentage); +} + void cpu_ticks_init(void) { seqlock_init(&timers_state.vm_clock_seqlock, NULL); vmstate_register(NULL, 0, &vmstate_timers, &timers_state); + throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT, + cpu_throttle_timer_tick, NULL); } void configure_icount(QemuOpts *opts, Error **errp) |