diff options
| -rw-r--r-- | cpus.c | 295 | ||||
| -rw-r--r-- | exec-all.h | 14 | ||||
| -rw-r--r-- | exec.c | 3 | ||||
| -rw-r--r-- | qemu-common.h | 4 | ||||
| -rw-r--r-- | qemu-timer.c | 279 | ||||
| -rw-r--r-- | qemu-timer.h | 24 |
6 files changed, 296 insertions, 323 deletions
@@ -65,6 +65,281 @@ static CPUState *next_cpu; /***********************************************************/ +/* guest cycle counter */ + +/* Conversion factor from emulated instructions to virtual clock ticks. */ +static int icount_time_shift; +/* Arbitrarily pick 1MIPS as the minimum allowable speed. */ +#define MAX_ICOUNT_SHIFT 10 +/* Compensate for varying guest execution speed. */ +static int64_t qemu_icount_bias; +static QEMUTimer *icount_rt_timer; +static QEMUTimer *icount_vm_timer; +static QEMUTimer *icount_warp_timer; +static int64_t vm_clock_warp_start; +static int64_t qemu_icount; + +typedef struct TimersState { + int64_t cpu_ticks_prev; + int64_t cpu_ticks_offset; + int64_t cpu_clock_offset; + int32_t cpu_ticks_enabled; + int64_t dummy; +} TimersState; + +TimersState timers_state; + +/* Return the virtual CPU time, based on the instruction counter. */ +int64_t cpu_get_icount(void) +{ + int64_t icount; + CPUState *env = cpu_single_env;; + + icount = qemu_icount; + if (env) { + if (!can_do_io(env)) { + fprintf(stderr, "Bad clock read\n"); + } + icount -= (env->icount_decr.u16.low + env->icount_extra); + } + return qemu_icount_bias + (icount << icount_time_shift); +} + +/* return the host CPU cycle counter and handle stop/restart */ +int64_t cpu_get_ticks(void) +{ + if (use_icount) { + return cpu_get_icount(); + } + if (!timers_state.cpu_ticks_enabled) { + return timers_state.cpu_ticks_offset; + } else { + int64_t ticks; + ticks = cpu_get_real_ticks(); + if (timers_state.cpu_ticks_prev > ticks) { + /* Note: non increasing ticks may happen if the host uses + software suspend */ + timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks; + } + timers_state.cpu_ticks_prev = ticks; + return ticks + timers_state.cpu_ticks_offset; + } +} + +/* return the host CPU monotonic timer and handle stop/restart */ +int64_t cpu_get_clock(void) +{ + int64_t ti; + if (!timers_state.cpu_ticks_enabled) { + return timers_state.cpu_clock_offset; + } else { + ti = get_clock(); + return ti + timers_state.cpu_clock_offset; + } +} + +/* enable cpu_get_ticks() */ +void cpu_enable_ticks(void) +{ + if (!timers_state.cpu_ticks_enabled) { + timers_state.cpu_ticks_offset -= cpu_get_real_ticks(); + timers_state.cpu_clock_offset -= get_clock(); + timers_state.cpu_ticks_enabled = 1; + } +} + +/* disable cpu_get_ticks() : the clock is stopped. You must not call + cpu_get_ticks() after that. */ +void cpu_disable_ticks(void) +{ + if (timers_state.cpu_ticks_enabled) { + timers_state.cpu_ticks_offset = cpu_get_ticks(); + timers_state.cpu_clock_offset = cpu_get_clock(); + timers_state.cpu_ticks_enabled = 0; + } +} + +/* Correlation between real and virtual time is always going to be + fairly approximate, so ignore small variation. + When the guest is idle real and virtual time will be aligned in + the IO wait loop. */ +#define ICOUNT_WOBBLE (get_ticks_per_sec() / 10) + +static void icount_adjust(void) +{ + int64_t cur_time; + int64_t cur_icount; + int64_t delta; + static int64_t last_delta; + /* If the VM is not running, then do nothing. */ + if (!runstate_is_running()) { + return; + } + cur_time = cpu_get_clock(); + cur_icount = qemu_get_clock_ns(vm_clock); + delta = cur_icount - cur_time; + /* FIXME: This is a very crude algorithm, somewhat prone to oscillation. */ + if (delta > 0 + && last_delta + ICOUNT_WOBBLE < delta * 2 + && icount_time_shift > 0) { + /* The guest is getting too far ahead. Slow time down. */ + icount_time_shift--; + } + if (delta < 0 + && last_delta - ICOUNT_WOBBLE > delta * 2 + && icount_time_shift < MAX_ICOUNT_SHIFT) { + /* The guest is getting too far behind. Speed time up. */ + icount_time_shift++; + } + last_delta = delta; + qemu_icount_bias = cur_icount - (qemu_icount << icount_time_shift); +} + +static void icount_adjust_rt(void *opaque) +{ + qemu_mod_timer(icount_rt_timer, + qemu_get_clock_ms(rt_clock) + 1000); + icount_adjust(); +} + +static void icount_adjust_vm(void *opaque) +{ + qemu_mod_timer(icount_vm_timer, + qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 10); + icount_adjust(); +} + +static int64_t qemu_icount_round(int64_t count) +{ + return (count + (1 << icount_time_shift) - 1) >> icount_time_shift; +} + +static void icount_warp_rt(void *opaque) +{ + if (vm_clock_warp_start == -1) { + return; + } + + if (runstate_is_running()) { + int64_t clock = qemu_get_clock_ns(rt_clock); + int64_t warp_delta = clock - vm_clock_warp_start; + if (use_icount == 1) { + qemu_icount_bias += warp_delta; + } else { + /* + * In adaptive mode, do not let the vm_clock run too + * far ahead of real time. + */ + int64_t cur_time = cpu_get_clock(); + int64_t cur_icount = qemu_get_clock_ns(vm_clock); + int64_t delta = cur_time - cur_icount; + qemu_icount_bias += MIN(warp_delta, delta); + } + if (qemu_clock_expired(vm_clock)) { + qemu_notify_event(); + } + } + vm_clock_warp_start = -1; +} + +void qemu_clock_warp(QEMUClock *clock) +{ + int64_t deadline; + + /* + * There are too many global variables to make the "warp" behavior + * applicable to other clocks. But a clock argument removes the + * need for if statements all over the place. + */ + if (clock != vm_clock || !use_icount) { + return; + } + + /* + * If the CPUs have been sleeping, advance the vm_clock timer now. This + * ensures that the deadline for the timer is computed correctly below. + * This also makes sure that the insn counter is synchronized before the + * CPU starts running, in case the CPU is woken by an event other than + * the earliest vm_clock timer. + */ + icount_warp_rt(NULL); + if (!all_cpu_threads_idle() || !qemu_clock_has_timers(vm_clock)) { + qemu_del_timer(icount_warp_timer); + return; + } + + vm_clock_warp_start = qemu_get_clock_ns(rt_clock); + deadline = qemu_clock_deadline(vm_clock); + if (deadline > 0) { + /* + * Ensure the vm_clock proceeds even when the virtual CPU goes to + * sleep. Otherwise, the CPU might be waiting for a future timer + * interrupt to wake it up, but the interrupt never comes because + * the vCPU isn't running any insns and thus doesn't advance the + * vm_clock. + * + * An extreme solution for this problem would be to never let VCPUs + * sleep in icount mode if there is a pending vm_clock timer; rather + * time could just advance to the next vm_clock event. Instead, we + * do stop VCPUs and only advance vm_clock after some "real" time, + * (related to the time left until the next event) has passed. This + * rt_clock timer will do this. This avoids that the warps are too + * visible externally---for example, you will not be sending network + * packets continously instead of every 100ms. + */ + qemu_mod_timer(icount_warp_timer, vm_clock_warp_start + deadline); + } else { + qemu_notify_event(); + } +} + +static const VMStateDescription vmstate_timers = { + .name = "timer", + .version_id = 2, + .minimum_version_id = 1, + .minimum_version_id_old = 1, + .fields = (VMStateField[]) { + VMSTATE_INT64(cpu_ticks_offset, TimersState), + VMSTATE_INT64(dummy, TimersState), + VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2), + VMSTATE_END_OF_LIST() + } +}; + +void configure_icount(const char *option) +{ + vmstate_register(NULL, 0, &vmstate_timers, &timers_state); + if (!option) { + return; + } + + icount_warp_timer = qemu_new_timer_ns(rt_clock, icount_warp_rt, NULL); + if (strcmp(option, "auto") != 0) { + icount_time_shift = strtol(option, NULL, 0); + use_icount = 1; + return; + } + + use_icount = 2; + + /* 125MIPS seems a reasonable initial guess at the guest speed. + It will be corrected fairly quickly anyway. */ + icount_time_shift = 3; + + /* Have both realtime and virtual time triggers for speed adjustment. + The realtime trigger catches emulated time passing too slowly, + the virtual time trigger catches emulated time passing too fast. + Realtime triggers occur even when idle, so use them less frequently + than VM triggers. */ + icount_rt_timer = qemu_new_timer_ms(rt_clock, icount_adjust_rt, NULL); + qemu_mod_timer(icount_rt_timer, + qemu_get_clock_ms(rt_clock) + 1000); + icount_vm_timer = qemu_new_timer_ns(vm_clock, icount_adjust_vm, NULL); + qemu_mod_timer(icount_vm_timer, + qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 10); +} + +/***********************************************************/ void hw_error(const char *fmt, ...) { va_list ap; @@ -686,7 +961,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) while (1) { cpu_exec_all(); - if (use_icount && qemu_next_icount_deadline() <= 0) { + if (use_icount && qemu_clock_deadline(vm_clock) <= 0) { qemu_notify_event(); } qemu_tcg_wait_io_event(); @@ -914,7 +1189,7 @@ static int tcg_cpu_exec(CPUState *env) qemu_icount -= (env->icount_decr.u16.low + env->icount_extra); env->icount_decr.u16.low = 0; env->icount_extra = 0; - count = qemu_icount_round(qemu_next_icount_deadline()); + count = qemu_icount_round(qemu_clock_deadline(vm_clock)); qemu_icount += count; decr = (count > 0xffff) ? 0xffff : count; count -= decr; @@ -1006,22 +1281,6 @@ void set_cpu_log_filename(const char *optarg) cpu_set_log_filename(optarg); } -/* Return the virtual CPU time, based on the instruction counter. */ -int64_t cpu_get_icount(void) -{ - int64_t icount; - CPUState *env = cpu_single_env;; - - icount = qemu_icount; - if (env) { - if (!can_do_io(env)) { - fprintf(stderr, "Bad clock read\n"); - } - icount -= (env->icount_decr.u16.low + env->icount_extra); - } - return qemu_icount_bias + (icount << icount_time_shift); -} - void list_cpus(FILE *f, fprintf_function cpu_fprintf, const char *optarg) { /* XXX: implement xxx_cpu_list for targets that still miss it */ diff --git a/exec-all.h b/exec-all.h index 1120f84661..72ef246793 100644 --- a/exec-all.h +++ b/exec-all.h @@ -356,4 +356,18 @@ extern int singlestep; /* cpu-exec.c */ extern volatile sig_atomic_t exit_request; +/* Deterministic execution requires that IO only be performed on the last + instruction of a TB so that interrupts take effect immediately. */ +static inline int can_do_io(CPUState *env) +{ + if (!use_icount) { + return 1; + } + /* If not executing code then assume we are ok. */ + if (!env->current_tb) { + return 1; + } + return env->can_do_io != 0; +} + #endif @@ -125,9 +125,6 @@ CPUState *cpu_single_env; 1 = Precise instruction counting. 2 = Adaptive rate instruction counting. */ int use_icount = 0; -/* Current instruction counter. While executing translated code this may - include some instructions that have not yet been executed. */ -int64_t qemu_icount; typedef struct PageDesc { /* list of TBs intersecting this ram page */ diff --git a/qemu-common.h b/qemu-common.h index 5e87bdf2f2..fffdefdeca 100644 --- a/qemu-common.h +++ b/qemu-common.h @@ -96,6 +96,10 @@ static inline char *realpath(const char *path, char *resolved_path) } #endif +/* icount */ +void configure_icount(const char *option); +extern int use_icount; + /* FIXME: Remove NEED_CPU_H. */ #ifndef NEED_CPU_H diff --git a/qemu-timer.c b/qemu-timer.c index ebb50890e8..8129af6ede 100644 --- a/qemu-timer.c +++ b/qemu-timer.c @@ -46,82 +46,6 @@ #include "qemu-timer.h" -/* Conversion factor from emulated instructions to virtual clock ticks. */ -int icount_time_shift; -/* Arbitrarily pick 1MIPS as the minimum allowable speed. */ -#define MAX_ICOUNT_SHIFT 10 -/* Compensate for varying guest execution speed. */ -int64_t qemu_icount_bias; -static QEMUTimer *icount_rt_timer; -static QEMUTimer *icount_vm_timer; - -/***********************************************************/ -/* guest cycle counter */ - -typedef struct TimersState { - int64_t cpu_ticks_prev; - int64_t cpu_ticks_offset; - int64_t cpu_clock_offset; - int32_t cpu_ticks_enabled; - int64_t dummy; -} TimersState; - -TimersState timers_state; - -/* return the host CPU cycle counter and handle stop/restart */ -int64_t cpu_get_ticks(void) -{ - if (use_icount) { - return cpu_get_icount(); - } - if (!timers_state.cpu_ticks_enabled) { - return timers_state.cpu_ticks_offset; - } else { - int64_t ticks; - ticks = cpu_get_real_ticks(); - if (timers_state.cpu_ticks_prev > ticks) { - /* Note: non increasing ticks may happen if the host uses - software suspend */ - timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks; - } - timers_state.cpu_ticks_prev = ticks; - return ticks + timers_state.cpu_ticks_offset; - } -} - -/* return the host CPU monotonic timer and handle stop/restart */ -static int64_t cpu_get_clock(void) -{ - int64_t ti; - if (!timers_state.cpu_ticks_enabled) { - return timers_state.cpu_clock_offset; - } else { - ti = get_clock(); - return ti + timers_state.cpu_clock_offset; - } -} - -/* enable cpu_get_ticks() */ -void cpu_enable_ticks(void) -{ - if (!timers_state.cpu_ticks_enabled) { - timers_state.cpu_ticks_offset -= cpu_get_real_ticks(); - timers_state.cpu_clock_offset -= get_clock(); - timers_state.cpu_ticks_enabled = 1; - } -} - -/* disable cpu_get_ticks() : the clock is stopped. You must not call - cpu_get_ticks() after that. */ -void cpu_disable_ticks(void) -{ - if (timers_state.cpu_ticks_enabled) { - timers_state.cpu_ticks_offset = cpu_get_ticks(); - timers_state.cpu_clock_offset = cpu_get_clock(); - timers_state.cpu_ticks_enabled = 0; - } -} - /***********************************************************/ /* timers */ @@ -133,7 +57,6 @@ struct QEMUClock { int type; int enabled; - QEMUTimer *warp_timer; QEMUTimer *active_timers; NotifierList reset_notifiers; @@ -252,61 +175,6 @@ static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta); #endif /* _WIN32 */ -/* Correlation between real and virtual time is always going to be - fairly approximate, so ignore small variation. - When the guest is idle real and virtual time will be aligned in - the IO wait loop. */ -#define ICOUNT_WOBBLE (get_ticks_per_sec() / 10) - -static void icount_adjust(void) -{ - int64_t cur_time; - int64_t cur_icount; - int64_t delta; - static int64_t last_delta; - /* If the VM is not running, then do nothing. */ - if (!runstate_is_running()) - return; - - cur_time = cpu_get_clock(); - cur_icount = qemu_get_clock_ns(vm_clock); - delta = cur_icount - cur_time; - /* FIXME: This is a very crude algorithm, somewhat prone to oscillation. */ - if (delta > 0 - && last_delta + ICOUNT_WOBBLE < delta * 2 - && icount_time_shift > 0) { - /* The guest is getting too far ahead. Slow time down. */ - icount_time_shift--; - } - if (delta < 0 - && last_delta - ICOUNT_WOBBLE > delta * 2 - && icount_time_shift < MAX_ICOUNT_SHIFT) { - /* The guest is getting too far behind. Speed time up. */ - icount_time_shift++; - } - last_delta = delta; - qemu_icount_bias = cur_icount - (qemu_icount << icount_time_shift); -} - -static void icount_adjust_rt(void * opaque) -{ - qemu_mod_timer(icount_rt_timer, - qemu_get_clock_ms(rt_clock) + 1000); - icount_adjust(); -} - -static void icount_adjust_vm(void * opaque) -{ - qemu_mod_timer(icount_vm_timer, - qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 10); - icount_adjust(); -} - -int64_t qemu_icount_round(int64_t count) -{ - return (count + (1 << icount_time_shift) - 1) >> icount_time_shift; -} - static struct qemu_alarm_timer alarm_timers[] = { #ifndef _WIN32 #ifdef __linux__ @@ -411,90 +279,6 @@ void qemu_clock_enable(QEMUClock *clock, int enabled) clock->enabled = enabled; } -static int64_t vm_clock_warp_start; - -static void icount_warp_rt(void *opaque) -{ - if (vm_clock_warp_start == -1) { - return; - } - - if (runstate_is_running()) { - int64_t clock = qemu_get_clock_ns(rt_clock); - int64_t warp_delta = clock - vm_clock_warp_start; - if (use_icount == 1) { - qemu_icount_bias += warp_delta; - } else { - /* - * In adaptive mode, do not let the vm_clock run too - * far ahead of real time. - */ - int64_t cur_time = cpu_get_clock(); - int64_t cur_icount = qemu_get_clock_ns(vm_clock); - int64_t delta = cur_time - cur_icount; - qemu_icount_bias += MIN(warp_delta, delta); - } - if (qemu_timer_expired(vm_clock->active_timers, - qemu_get_clock_ns(vm_clock))) { - qemu_notify_event(); - } - } - vm_clock_warp_start = -1; -} - -void qemu_clock_warp(QEMUClock *clock) -{ - int64_t deadline; - - if (!clock->warp_timer) { - return; - } - - /* - * There are too many global variables to make the "warp" behavior - * applicable to other clocks. But a clock argument removes the - * need for if statements all over the place. - */ - assert(clock == vm_clock); - - /* - * If the CPUs have been sleeping, advance the vm_clock timer now. This - * ensures that the deadline for the timer is computed correctly below. - * This also makes sure that the insn counter is synchronized before the - * CPU starts running, in case the CPU is woken by an event other than - * the earliest vm_clock timer. - */ - icount_warp_rt(NULL); - if (!all_cpu_threads_idle() || !clock->active_timers) { - qemu_del_timer(clock->warp_timer); - return; - } - - vm_clock_warp_start = qemu_get_clock_ns(rt_clock); - deadline = qemu_next_icount_deadline(); - if (deadline > 0) { - /* - * Ensure the vm_clock proceeds even when the virtual CPU goes to - * sleep. Otherwise, the CPU might be waiting for a future timer - * interrupt to wake it up, but the interrupt never comes because - * the vCPU isn't running any insns and thus doesn't advance the - * vm_clock. - * - * An extreme solution for this problem would be to never let VCPUs - * sleep in icount mode if there is a pending vm_clock timer; rather - * time could just advance to the next vm_clock event. Instead, we - * do stop VCPUs and only advance vm_clock after some "real" time, - * (related to the time left until the next event) has passed. This - * rt_clock timer will do this. This avoids that the warps are too - * visible externally---for example, you will not be sending network - * packets continously instead of every 100ms. - */ - qemu_mod_timer(clock->warp_timer, vm_clock_warp_start + deadline); - } else { - qemu_notify_event(); - } -} - int64_t qemu_clock_has_timers(QEMUClock *clock) { return !!clock->active_timers; @@ -709,52 +493,6 @@ void qemu_get_timer(QEMUFile *f, QEMUTimer *ts) } } -static const VMStateDescription vmstate_timers = { - .name = "timer", - .version_id = 2, - .minimum_version_id = 1, - .minimum_version_id_old = 1, - .fields = (VMStateField []) { - VMSTATE_INT64(cpu_ticks_offset, TimersState), - VMSTATE_INT64(dummy, TimersState), - VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2), - VMSTATE_END_OF_LIST() - } -}; - -void configure_icount(const char *option) -{ - vmstate_register(NULL, 0, &vmstate_timers, &timers_state); - if (!option) - return; - - vm_clock->warp_timer = qemu_new_timer_ns(rt_clock, icount_warp_rt, NULL); - - if (strcmp(option, "auto") != 0) { - icount_time_shift = strtol(option, NULL, 0); - use_icount = 1; - return; - } - - use_icount = 2; - - /* 125MIPS seems a reasonable initial guess at the guest speed. - It will be corrected fairly quickly anyway. */ - icount_time_shift = 3; - - /* Have both realtime and virtual time triggers for speed adjustment. - The realtime trigger catches emulated time passing too slowly, - the virtual time trigger catches emulated time passing too fast. - Realtime triggers occur even when idle, so use them less frequently - than VM triggers. */ - icount_rt_timer = qemu_new_timer_ms(rt_clock, icount_adjust_rt, NULL); - qemu_mod_timer(icount_rt_timer, - qemu_get_clock_ms(rt_clock) + 1000); - icount_vm_timer = qemu_new_timer_ns(vm_clock, icount_adjust_vm, NULL); - qemu_mod_timer(icount_vm_timer, - qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 10); -} - void qemu_run_all_timers(void) { alarm_timer->pending = 0; @@ -821,23 +559,6 @@ static void host_alarm_handler(int host_signum) } } -int64_t qemu_next_icount_deadline(void) -{ - /* To avoid problems with overflow limit this to 2^32. */ - int64_t delta = INT32_MAX; - - assert(use_icount); - if (vm_clock->active_timers) { - delta = vm_clock->active_timers->expire_time - - qemu_get_clock_ns(vm_clock); - } - - if (delta < 0) - delta = 0; - - return delta; -} - #if defined(__linux__) #include "compatfd.h" diff --git a/qemu-timer.h b/qemu-timer.h index 4578075f6f..ce576b90a4 100644 --- a/qemu-timer.h +++ b/qemu-timer.h @@ -58,9 +58,7 @@ int qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time); void qemu_run_all_timers(void); int qemu_alarm_pending(void); -int64_t qemu_next_icount_deadline(void); void configure_alarms(char const *opt); -void configure_icount(const char *option); int qemu_calculate_timeout(void); void init_clocks(void); int init_timer_alarm(void); @@ -153,12 +151,8 @@ void ptimer_run(ptimer_state *s, int oneshot); void ptimer_stop(ptimer_state *s); /* icount */ -int64_t qemu_icount_round(int64_t count); -extern int64_t qemu_icount; -extern int use_icount; -extern int icount_time_shift; -extern int64_t qemu_icount_bias; int64_t cpu_get_icount(void); +int64_t cpu_get_clock(void); /*******************************************/ /* host CPU ticks (if available) */ @@ -314,22 +308,6 @@ static inline int64_t cpu_get_real_ticks (void) } #endif -#ifdef NEED_CPU_H -/* Deterministic execution requires that IO only be performed on the last - instruction of a TB so that interrupts take effect immediately. */ -static inline int can_do_io(CPUState *env) -{ - if (!use_icount) - return 1; - - /* If not executing code then assume we are ok. */ - if (!env->current_tb) - return 1; - - return env->can_do_io != 0; -} -#endif - #ifdef CONFIG_PROFILER static inline int64_t profile_getclock(void) { |