}
}
+#ifndef CONFIG_IOTHREAD
static int64_t qemu_icount_delta(void)
{
- if (use_icount == 1) {
+ if (!use_icount) {
+ return 5000 * (int64_t) 1000000;
+ } else if (use_icount == 1) {
/* When not using an adaptive execution frequency
we tend to get badly out of sync with real time,
so just delay for a reasonable amount of time. */
return cpu_get_icount() - cpu_get_clock();
}
}
+#endif
/* enable cpu_get_ticks() */
void cpu_enable_ticks(void)
struct QEMUClock {
int type;
int enabled;
+
+ QEMUTimer *warp_timer;
};
struct QEMUTimer {
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 (vm_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(active_timers[QEMU_CLOCK_VIRTUAL],
+ 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() || !active_timers[clock->type]) {
+ 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();
+ }
+}
+
QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
QEMUTimerCB *cb, void *opaque)
{
qemu_rearm_alarm_timer(alarm_timer);
}
/* Interrupt execution to force deadline recalculation. */
- if (use_icount)
+ qemu_clock_warp(ts->clock);
+ if (use_icount) {
qemu_notify_event();
+ }
}
}
if (!option)
return;
+#ifdef CONFIG_IOTHREAD
+ vm_clock->warp_timer = qemu_new_timer_ns(rt_clock, icount_warp_rt, NULL);
+#endif
+
if (strcmp(option, "auto") != 0) {
icount_time_shift = strtol(option, NULL, 0);
use_icount = 1;
}
}
-int64_t qemu_next_deadline(void)
+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 (active_timers[QEMU_CLOCK_VIRTUAL]) {
delta = active_timers[QEMU_CLOCK_VIRTUAL]->expire_time -
qemu_get_clock_ns(vm_clock);
}
- if (active_timers[QEMU_CLOCK_HOST]) {
- int64_t hdelta = active_timers[QEMU_CLOCK_HOST]->expire_time -
- qemu_get_clock_ns(host_clock);
- if (hdelta < delta)
- delta = hdelta;
- }
if (delta < 0)
delta = 0;
int qemu_calculate_timeout(void)
{
+#ifndef CONFIG_IOTHREAD
int timeout;
- int64_t add;
- int64_t delta;
-
- /* When using icount, making forward progress with qemu_icount when the
- guest CPU is idle is critical. We only use the static io-thread timeout
- for non icount runs. */
- if (!use_icount || !vm_running) {
- return 5000;
- }
- /* Advance virtual time to the next event. */
- delta = qemu_icount_delta();
- if (delta > 0) {
- /* If virtual time is ahead of real time then just
- wait for IO. */
- timeout = (delta + 999999) / 1000000;
- } else {
- /* Wait for either IO to occur or the next
- timer event. */
- add = qemu_next_deadline();
- /* We advance the timer before checking for IO.
- Limit the amount we advance so that early IO
- activity won't get the guest too far ahead. */
- if (add > 10000000)
- add = 10000000;
- delta += add;
- qemu_icount += qemu_icount_round (add);
- timeout = delta / 1000000;
- if (timeout < 0)
- timeout = 0;
+ if (!vm_running)
+ timeout = 5000;
+ else {
+ /* XXX: use timeout computed from timers */
+ int64_t add;
+ int64_t delta;
+ /* Advance virtual time to the next event. */
+ delta = qemu_icount_delta();
+ if (delta > 0) {
+ /* If virtual time is ahead of real time then just
+ wait for IO. */
+ timeout = (delta + 999999) / 1000000;
+ } else {
+ /* Wait for either IO to occur or the next
+ timer event. */
+ add = qemu_next_icount_deadline();
+ /* We advance the timer before checking for IO.
+ Limit the amount we advance so that early IO
+ activity won't get the guest too far ahead. */
+ if (add > 10000000)
+ add = 10000000;
+ delta += add;
+ qemu_icount += qemu_icount_round (add);
+ timeout = delta / 1000000;
+ if (timeout < 0)
+ timeout = 0;
+ }
}
return timeout;
+#else /* CONFIG_IOTHREAD */
+ return 1000;
+#endif
}
projects / qemu.git / blobdiff