Commit 946fb27c authored by Paolo Bonzini's avatar Paolo Bonzini

qemu-timer: move icount to cpus.c

None of this is needed by tools, and most of it can even be made static
inside cpus.c.
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent dc2dfcf0
......@@ -64,6 +64,281 @@
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, ...)
{
......@@ -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 */
......
......@@ -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 */
......
......@@ -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
......
......@@ -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;