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aio / timers: Split QEMUClock into QEMUClock and QEMUTimerList

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Split QEMUClock into QEMUClock and QEMUTimerList so that we can
have more than one QEMUTimerList associated with the same clock.

Introduce a main_loop_timerlist concept and make existing
qemu_clock_* calls that actually should operate on a QEMUTimerList
call the relevant QEMUTimerList implementations, using the clock's
default timerlist. This vastly reduces the invasiveness of this
change and means the API stays constant for existing users.

Introduce a list of QEMUTimerLists associated with each clock
so that reenabling the clock can cause all the notifiers
to be called. Note the code to do the notifications is added
in a later patch.

Switch QEMUClockType to an enum. Remove global variables vm_clock,
host_clock and rt_clock and add compatibility defines. Do not
fix qemu_next_alarm_deadline as it's going to be deleted.

Add qemu_clock_use_for_deadline to indicate whether a particular
clock should be used for deadline calculations. When use_icount
is true, vm_clock should not be used for deadline calculations
as it does not contain a nanosecond count. Instead, icount
timeouts come from the execution thread doing aio_notify or
qemu_notify as appropriate. This function is used in the next
patch.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Alex Bligh 2013-08-21 16:02:46 +01:00 • committed by Stefan Hajnoczi
parent f9a976b740
commit ff83c66ecc
2 changed files with 476 additions and 79 deletions
Download patch file Download diff file Expand all files Collapse all files

207
qemu-timer.c
View file

@ -49,22 +49,29 @@
/* timers */
struct QEMUClock {
QEMUTimer *active_timers;
QEMUTimerList *main_loop_timerlist;
QLIST_HEAD(, QEMUTimerList) timerlists;
NotifierList reset_notifiers;
int64_t last;
int type;
QEMUClockType type;
bool enabled;
};
struct QEMUTimer {
int64_t expire_time; /* in nanoseconds */
QEMUClock *qemu_clocks[QEMU_CLOCK_MAX];
/* A QEMUTimerList is a list of timers attached to a clock. More
* than one QEMUTimerList can be attached to each clock, for instance
* used by different AioContexts / threads. Each clock also has
* a list of the QEMUTimerLists associated with it, in order that
* reenabling the clock can call all the notifiers.
*/
struct QEMUTimerList {
QEMUClock *clock;
QEMUTimerCB *cb;
void *opaque;
QEMUTimer *next;
int scale;
QEMUTimer *active_timers;
QLIST_ENTRY(QEMUTimerList) list;
};
struct qemu_alarm_timer {
@ -93,21 +100,25 @@ static int64_t qemu_next_alarm_deadline(void)
{
int64_t delta = INT64_MAX;
int64_t rtdelta;
int64_t hdelta;
if (!use_icount && vm_clock->enabled && vm_clock->active_timers) {
delta = vm_clock->active_timers->expire_time -
qemu_get_clock_ns(vm_clock);
if (!use_icount && vm_clock->enabled &&
vm_clock->main_loop_timerlist->active_timers) {
delta = vm_clock->main_loop_timerlist->active_timers->expire_time -
qemu_get_clock_ns(vm_clock);
}
if (host_clock->enabled && host_clock->active_timers) {
int64_t hdelta = host_clock->active_timers->expire_time -
qemu_get_clock_ns(host_clock);
if (host_clock->enabled &&
host_clock->main_loop_timerlist->active_timers) {
hdelta = host_clock->main_loop_timerlist->active_timers->expire_time -
qemu_get_clock_ns(host_clock);
if (hdelta < delta) {
delta = hdelta;
}
}
if (rt_clock->enabled && rt_clock->active_timers) {
rtdelta = (rt_clock->active_timers->expire_time -
qemu_get_clock_ns(rt_clock));
if (rt_clock->enabled &&
rt_clock->main_loop_timerlist->active_timers) {
rtdelta = (rt_clock->main_loop_timerlist->active_timers->expire_time -
qemu_get_clock_ns(rt_clock));
if (rtdelta < delta) {
delta = rtdelta;
}
@ -231,11 +242,42 @@ next:
}
}
QEMUClock *rt_clock;
QEMUClock *vm_clock;
QEMUClock *host_clock;
static QEMUTimerList *timerlist_new_from_clock(QEMUClock *clock)
{
QEMUTimerList *timer_list;
static QEMUClock *qemu_clock_new(int type)
/* Assert if we do not have a clock. If you see this
* assertion in means that the clocks have not been
* initialised before a timerlist is needed. This
* normally happens if an AioContext is used before
* init_clocks() is called within main().
*/
assert(clock);
timer_list = g_malloc0(sizeof(QEMUTimerList));
timer_list->clock = clock;
QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
return timer_list;
}
QEMUTimerList *timerlist_new(QEMUClockType type)
{
return timerlist_new_from_clock(qemu_clock_ptr(type));
}
void timerlist_free(QEMUTimerList *timer_list)
{
assert(!timerlist_has_timers(timer_list));
if (timer_list->clock) {
QLIST_REMOVE(timer_list, list);
if (timer_list->clock->main_loop_timerlist == timer_list) {
timer_list->clock->main_loop_timerlist = NULL;
}
}
g_free(timer_list);
}
static QEMUClock *qemu_clock_new(QEMUClockType type)
{
QEMUClock *clock;
@ -243,10 +285,17 @@ static QEMUClock *qemu_clock_new(int type)
clock->type = type;
clock->enabled = true;
clock->last = INT64_MIN;
QLIST_INIT(&clock->timerlists);
notifier_list_init(&clock->reset_notifiers);
clock->main_loop_timerlist = timerlist_new_from_clock(clock);
return clock;
}
bool qemu_clock_use_for_deadline(QEMUClock *clock)
{
return !(use_icount && (clock->type == QEMU_CLOCK_VIRTUAL));
}
void qemu_clock_enable(QEMUClock *clock, bool enabled)
{
bool old = clock->enabled;
@ -256,24 +305,36 @@ void qemu_clock_enable(QEMUClock *clock, bool enabled)
}
}
int64_t qemu_clock_has_timers(QEMUClock *clock)
bool timerlist_has_timers(QEMUTimerList *timer_list)
{
return !!clock->active_timers;
return !!timer_list->active_timers;
}
int64_t qemu_clock_expired(QEMUClock *clock)
bool qemu_clock_has_timers(QEMUClock *clock)
{
return (clock->active_timers &&
clock->active_timers->expire_time < qemu_get_clock_ns(clock));
return timerlist_has_timers(clock->main_loop_timerlist);
}
int64_t qemu_clock_deadline(QEMUClock *clock)
bool timerlist_expired(QEMUTimerList *timer_list)
{
return (timer_list->active_timers &&
timer_list->active_timers->expire_time <
qemu_get_clock_ns(timer_list->clock));
}
bool qemu_clock_expired(QEMUClock *clock)
{
return timerlist_expired(clock->main_loop_timerlist);
}
int64_t timerlist_deadline(QEMUTimerList *timer_list)
{
/* To avoid problems with overflow limit this to 2^32. */
int64_t delta = INT32_MAX;
if (clock->enabled && clock->active_timers) {
delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
if (timer_list->clock->enabled && timer_list->active_timers) {
delta = timer_list->active_timers->expire_time -
qemu_get_clock_ns(timer_list->clock);
}
if (delta < 0) {
delta = 0;
@ -281,20 +342,26 @@ int64_t qemu_clock_deadline(QEMUClock *clock)
return delta;
}
int64_t qemu_clock_deadline(QEMUClock *clock)
{
return timerlist_deadline(clock->main_loop_timerlist);
}
/*
* As above, but return -1 for no deadline, and do not cap to 2^32
* as we know the result is always positive.
*/
int64_t qemu_clock_deadline_ns(QEMUClock *clock)
int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
{
int64_t delta;
if (!clock->enabled || !clock->active_timers) {
if (!timer_list->clock->enabled || !timer_list->active_timers) {
return -1;
}
delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
delta = timer_list->active_timers->expire_time -
qemu_get_clock_ns(timer_list->clock);
if (delta <= 0) {
return 0;
@ -303,6 +370,21 @@ int64_t qemu_clock_deadline_ns(QEMUClock *clock)
return delta;
}
int64_t qemu_clock_deadline_ns(QEMUClock *clock)
{
return timerlist_deadline_ns(clock->main_loop_timerlist);
}
QEMUClock *timerlist_get_clock(QEMUTimerList *timer_list)
{
return timer_list->clock;
}
QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClock *clock)
{
return clock->main_loop_timerlist;
}
/* Transition function to convert a nanosecond timeout to ms
* This is used where a system does not support ppoll
*/
@ -351,17 +433,21 @@ int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
}
QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
QEMUTimerCB *cb, void *opaque)
void timer_init(QEMUTimer *ts,
QEMUTimerList *timer_list, int scale,
QEMUTimerCB *cb, void *opaque)
{
QEMUTimer *ts;
ts = g_malloc0(sizeof(QEMUTimer));
ts->clock = clock;
ts->timer_list = timer_list;
ts->cb = cb;
ts->opaque = opaque;
ts->scale = scale;
return ts;
}
QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
QEMUTimerCB *cb, void *opaque)
{
return timer_new_tl(clock->main_loop_timerlist,
scale, cb, opaque);
}
void qemu_free_timer(QEMUTimer *ts)
@ -376,7 +462,7 @@ void qemu_del_timer(QEMUTimer *ts)
/* NOTE: this code must be signal safe because
timer_expired() can be called from a signal. */
pt = &ts->clock->active_timers;
pt = &ts->timer_list->active_timers;
for(;;) {
t = *pt;
if (!t)
@ -400,7 +486,7 @@ void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
/* add the timer in the sorted list */
/* NOTE: this code must be signal safe because
timer_expired() can be called from a signal. */
pt = &ts->clock->active_timers;
pt = &ts->timer_list->active_timers;
for(;;) {
t = *pt;
if (!timer_expired_ns(t, expire_time)) {
@ -413,12 +499,12 @@ void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
*pt = ts;
/* Rearm if necessary */
if (pt == &ts->clock->active_timers) {
if (pt == &ts->timer_list->active_timers) {
if (!alarm_timer->pending) {
qemu_rearm_alarm_timer(alarm_timer);
}
/* Interrupt execution to force deadline recalculation. */
qemu_clock_warp(ts->clock);
qemu_clock_warp(ts->timer_list->clock);
if (use_icount) {
qemu_notify_event();
}
@ -433,7 +519,7 @@ void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
bool timer_pending(QEMUTimer *ts)
{
QEMUTimer *t;
for (t = ts->clock->active_timers; t != NULL; t = t->next) {
for (t = ts->timer_list->active_timers; t != NULL; t = t->next) {
if (t == ts) {
return true;
}
@ -446,23 +532,24 @@ bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
return timer_expired_ns(timer_head, current_time * timer_head->scale);
}
bool qemu_run_timers(QEMUClock *clock)
bool timerlist_run_timers(QEMUTimerList *timer_list)
{
QEMUTimer *ts;
int64_t current_time;
bool progress = false;
if (!clock->enabled)
if (!timer_list->clock->enabled) {
return progress;
}
current_time = qemu_get_clock_ns(clock);
current_time = qemu_get_clock_ns(timer_list->clock);
for(;;) {
ts = clock->active_timers;
ts = timer_list->active_timers;
if (!timer_expired_ns(ts, current_time)) {
break;
}
/* remove timer from the list before calling the callback */
clock->active_timers = ts->next;
timer_list->active_timers = ts->next;
ts->next = NULL;
/* run the callback (the timer list can be modified) */
@ -472,6 +559,11 @@ bool qemu_run_timers(QEMUClock *clock)
return progress;
}
bool qemu_run_timers(QEMUClock *clock)
{
return timerlist_run_timers(clock->main_loop_timerlist);
}
int64_t qemu_get_clock_ns(QEMUClock *clock)
{
int64_t now, last;
@ -509,11 +601,13 @@ void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
void init_clocks(void)
{
if (!rt_clock) {
rt_clock = qemu_clock_new(QEMU_CLOCK_REALTIME);
vm_clock = qemu_clock_new(QEMU_CLOCK_VIRTUAL);
host_clock = qemu_clock_new(QEMU_CLOCK_HOST);
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
if (!qemu_clocks[type]) {
qemu_clocks[type] = qemu_clock_new(type);
}
}
#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
#endif
@ -530,9 +624,10 @@ bool qemu_run_all_timers(void)
alarm_timer->pending = false;
/* vm time timers */
progress |= qemu_run_timers(vm_clock);
progress |= qemu_run_timers(rt_clock);
progress |= qemu_run_timers(host_clock);
QEMUClockType type;
for (type = 0; type < QEMU_CLOCK_MAX; type++) {
progress |= qemu_run_timers(qemu_clock_ptr(type));
}
/* rearm timer, if not periodic */
if (alarm_timer->expired) {