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qemu/qemu-timer.c
Paolo Bonzini 144b97c26c qemu-timer: simplify qemu_run_timers 
ptimer_head is an invariant pointer to clock->active_timers.
Remove it, and just reference clock->active_timers directly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
2012-09-23 07:11:29 +01:00

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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "sysemu.h"
#include "net.h"
#include "monitor.h"
#include "console.h"
#include "hw/hw.h"
#include "qemu-timer.h"
#ifdef _WIN32
#include <mmsystem.h>
#endif
/***********************************************************/
/* timers */
#define QEMU_CLOCK_REALTIME 0
#define QEMU_CLOCK_VIRTUAL 1
#define QEMU_CLOCK_HOST 2
struct QEMUClock {
QEMUTimer *active_timers;
NotifierList reset_notifiers;
int64_t last;
int type;
bool enabled;
};
struct QEMUTimer {
int64_t expire_time; /* in nanoseconds */
QEMUClock *clock;
QEMUTimerCB *cb;
void *opaque;
QEMUTimer *next;
int scale;
};
struct qemu_alarm_timer {
char const *name;
int (*start)(struct qemu_alarm_timer *t);
void (*stop)(struct qemu_alarm_timer *t);
void (*rearm)(struct qemu_alarm_timer *t, int64_t nearest_delta_ns);
#if defined(__linux__)
timer_t timer;
int fd;
#elif defined(_WIN32)
HANDLE timer;
#endif
bool expired;
bool pending;
};
static struct qemu_alarm_timer *alarm_timer;
static bool qemu_timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
{
return timer_head && (timer_head->expire_time <= current_time);
}
static int64_t qemu_next_alarm_deadline(void)
{
int64_t delta = INT64_MAX;
int64_t rtdelta;
if (!use_icount && vm_clock->enabled && vm_clock->active_timers) {
delta = vm_clock->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 (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 (rtdelta < delta) {
delta = rtdelta;
}
}
return delta;
}
static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
{
int64_t nearest_delta_ns = qemu_next_alarm_deadline();
if (nearest_delta_ns < INT64_MAX) {
t->rearm(t, nearest_delta_ns);
}
}
/* TODO: MIN_TIMER_REARM_NS should be optimized */
#define MIN_TIMER_REARM_NS 250000
#ifdef _WIN32
static int mm_start_timer(struct qemu_alarm_timer *t);
static void mm_stop_timer(struct qemu_alarm_timer *t);
static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
static int win32_start_timer(struct qemu_alarm_timer *t);
static void win32_stop_timer(struct qemu_alarm_timer *t);
static void win32_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
#else
static int unix_start_timer(struct qemu_alarm_timer *t);
static void unix_stop_timer(struct qemu_alarm_timer *t);
static void unix_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
#ifdef __linux__
static int dynticks_start_timer(struct qemu_alarm_timer *t);
static void dynticks_stop_timer(struct qemu_alarm_timer *t);
static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
#endif /* __linux__ */
#endif /* _WIN32 */
static struct qemu_alarm_timer alarm_timers[] = {
#ifndef _WIN32
#ifdef __linux__
{"dynticks", dynticks_start_timer,
dynticks_stop_timer, dynticks_rearm_timer},
#endif
{"unix", unix_start_timer, unix_stop_timer, unix_rearm_timer},
#else
{"mmtimer", mm_start_timer, mm_stop_timer, mm_rearm_timer},
{"dynticks", win32_start_timer, win32_stop_timer, win32_rearm_timer},
#endif
{NULL, }
};
static void show_available_alarms(void)
{
int i;
printf("Available alarm timers, in order of precedence:\n");
for (i = 0; alarm_timers[i].name; i++)
printf("%s\n", alarm_timers[i].name);
}
void configure_alarms(char const *opt)
{
int i;
int cur = 0;
int count = ARRAY_SIZE(alarm_timers) - 1;
char *arg;
char *name;
struct qemu_alarm_timer tmp;
if (is_help_option(opt)) {
show_available_alarms();
exit(0);
}
arg = g_strdup(opt);
/* Reorder the array */
name = strtok(arg, ",");
while (name) {
for (i = 0; i < count && alarm_timers[i].name; i++) {
if (!strcmp(alarm_timers[i].name, name))
break;
}
if (i == count) {
fprintf(stderr, "Unknown clock %s\n", name);
goto next;
}
if (i < cur)
/* Ignore */
goto next;
/* Swap */
tmp = alarm_timers[i];
alarm_timers[i] = alarm_timers[cur];
alarm_timers[cur] = tmp;
cur++;
next:
name = strtok(NULL, ",");
}
g_free(arg);
if (cur) {
/* Disable remaining timers */
for (i = cur; i < count; i++)
alarm_timers[i].name = NULL;
} else {
show_available_alarms();
exit(1);
}
}
QEMUClock *rt_clock;
QEMUClock *vm_clock;
QEMUClock *host_clock;
static QEMUClock *qemu_new_clock(int type)
{
QEMUClock *clock;
clock = g_malloc0(sizeof(QEMUClock));
clock->type = type;
clock->enabled = true;
clock->last = INT64_MIN;
notifier_list_init(&clock->reset_notifiers);
return clock;
}
void qemu_clock_enable(QEMUClock *clock, bool enabled)
{
bool old = clock->enabled;
clock->enabled = enabled;
if (enabled && !old) {
qemu_rearm_alarm_timer(alarm_timer);
}
}
int64_t qemu_clock_has_timers(QEMUClock *clock)
{
return !!clock->active_timers;
}
int64_t qemu_clock_expired(QEMUClock *clock)
{
return (clock->active_timers &&
clock->active_timers->expire_time < qemu_get_clock_ns(clock));
}
int64_t qemu_clock_deadline(QEMUClock *clock)
{
/* To avoid problems with overflow limit this to 2^32. */
int64_t delta = INT32_MAX;
if (clock->active_timers) {
delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
}
if (delta < 0) {
delta = 0;
}
return delta;
}
QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
QEMUTimerCB *cb, void *opaque)
{
QEMUTimer *ts;
ts = g_malloc0(sizeof(QEMUTimer));
ts->clock = clock;
ts->cb = cb;
ts->opaque = opaque;
ts->scale = scale;
return ts;
}
void qemu_free_timer(QEMUTimer *ts)
{
g_free(ts);
}
/* stop a timer, but do not dealloc it */
void qemu_del_timer(QEMUTimer *ts)
{
QEMUTimer **pt, *t;
/* NOTE: this code must be signal safe because
qemu_timer_expired() can be called from a signal. */
pt = &ts->clock->active_timers;
for(;;) {
t = *pt;
if (!t)
break;
if (t == ts) {
*pt = t->next;
break;
}
pt = &t->next;
}
}
/* modify the current timer so that it will be fired when current_time
>= expire_time. The corresponding callback will be called. */
void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
{
QEMUTimer **pt, *t;
qemu_del_timer(ts);
/* add the timer in the sorted list */
/* NOTE: this code must be signal safe because
qemu_timer_expired() can be called from a signal. */
pt = &ts->clock->active_timers;
for(;;) {
t = *pt;
if (!qemu_timer_expired_ns(t, expire_time)) {
break;
}
pt = &t->next;
}
ts->expire_time = expire_time;
ts->next = *pt;
*pt = ts;
/* Rearm if necessary */
if (pt == &ts->clock->active_timers) {
if (!alarm_timer->pending) {
qemu_rearm_alarm_timer(alarm_timer);
}
/* Interrupt execution to force deadline recalculation. */
qemu_clock_warp(ts->clock);
if (use_icount) {
qemu_notify_event();
}
}
}
void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
{
qemu_mod_timer_ns(ts, expire_time * ts->scale);
}
bool qemu_timer_pending(QEMUTimer *ts)
{
QEMUTimer *t;
for (t = ts->clock->active_timers; t != NULL; t = t->next) {
if (t == ts) {
return true;
}
}
return false;
}
bool qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time)
{
return qemu_timer_expired_ns(timer_head, current_time * timer_head->scale);
}
void qemu_run_timers(QEMUClock *clock)
{
QEMUTimer *ts;
int64_t current_time;
if (!clock->enabled)
return;
current_time = qemu_get_clock_ns(clock);
for(;;) {
ts = clock->active_timers;
if (!qemu_timer_expired_ns(ts, current_time)) {
break;
}
/* remove timer from the list before calling the callback */
clock->active_timers = ts->next;
ts->next = NULL;
/* run the callback (the timer list can be modified) */
ts->cb(ts->opaque);
}
}
int64_t qemu_get_clock_ns(QEMUClock *clock)
{
int64_t now, last;
switch(clock->type) {
case QEMU_CLOCK_REALTIME:
return get_clock();
default:
case QEMU_CLOCK_VIRTUAL:
if (use_icount) {
return cpu_get_icount();
} else {
return cpu_get_clock();
}
case QEMU_CLOCK_HOST:
now = get_clock_realtime();
last = clock->last;
clock->last = now;
if (now < last) {
notifier_list_notify(&clock->reset_notifiers, &now);
}
return now;
}
}
void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
{
notifier_list_add(&clock->reset_notifiers, notifier);
}
void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
{
notifier_remove(notifier);
}
void init_clocks(void)
{
rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
}
uint64_t qemu_timer_expire_time_ns(QEMUTimer *ts)
{
return qemu_timer_pending(ts) ? ts->expire_time : -1;
}
void qemu_run_all_timers(void)
{
alarm_timer->pending = false;
/* vm time timers */
qemu_run_timers(vm_clock);
qemu_run_timers(rt_clock);
qemu_run_timers(host_clock);
/* rearm timer, if not periodic */
if (alarm_timer->expired) {
alarm_timer->expired = false;
qemu_rearm_alarm_timer(alarm_timer);
}
}
#ifdef _WIN32
static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
#else
static void host_alarm_handler(int host_signum)
#endif
{
struct qemu_alarm_timer *t = alarm_timer;
if (!t)
return;
t->expired = true;
t->pending = true;
qemu_notify_event();
}
#if defined(__linux__)
#include "compatfd.h"
static int dynticks_start_timer(struct qemu_alarm_timer *t)
{
struct sigevent ev;
timer_t host_timer;
struct sigaction act;
sigfillset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = host_alarm_handler;
sigaction(SIGALRM, &act, NULL);
/*
* Initialize ev struct to 0 to avoid valgrind complaining
* about uninitialized data in timer_create call
*/
memset(&ev, 0, sizeof(ev));
ev.sigev_value.sival_int = 0;
ev.sigev_notify = SIGEV_SIGNAL;
#ifdef SIGEV_THREAD_ID
if (qemu_signalfd_available()) {
ev.sigev_notify = SIGEV_THREAD_ID;
ev._sigev_un._tid = qemu_get_thread_id();
}
#endif /* SIGEV_THREAD_ID */
ev.sigev_signo = SIGALRM;
if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
perror("timer_create");
return -1;
}
t->timer = host_timer;
return 0;
}
static void dynticks_stop_timer(struct qemu_alarm_timer *t)
{
timer_t host_timer = t->timer;
timer_delete(host_timer);
}
static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
int64_t nearest_delta_ns)
{
timer_t host_timer = t->timer;
struct itimerspec timeout;
int64_t current_ns;
if (nearest_delta_ns < MIN_TIMER_REARM_NS)
nearest_delta_ns = MIN_TIMER_REARM_NS;
/* check whether a timer is already running */
if (timer_gettime(host_timer, &timeout)) {
perror("gettime");
fprintf(stderr, "Internal timer error: aborting\n");
exit(1);
}
current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
if (current_ns && current_ns <= nearest_delta_ns)
return;
timeout.it_interval.tv_sec = 0;
timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
timeout.it_value.tv_sec = nearest_delta_ns / 1000000000;
timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
perror("settime");
fprintf(stderr, "Internal timer error: aborting\n");
exit(1);
}
}
#endif /* defined(__linux__) */
#if !defined(_WIN32)
static int unix_start_timer(struct qemu_alarm_timer *t)
{
struct sigaction act;
/* timer signal */
sigfillset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = host_alarm_handler;
sigaction(SIGALRM, &act, NULL);
return 0;
}
static void unix_rearm_timer(struct qemu_alarm_timer *t,
int64_t nearest_delta_ns)
{
struct itimerval itv;
int err;
if (nearest_delta_ns < MIN_TIMER_REARM_NS)
nearest_delta_ns = MIN_TIMER_REARM_NS;
itv.it_interval.tv_sec = 0;
itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
itv.it_value.tv_sec = nearest_delta_ns / 1000000000;
itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
err = setitimer(ITIMER_REAL, &itv, NULL);
if (err) {
perror("setitimer");
fprintf(stderr, "Internal timer error: aborting\n");
exit(1);
}
}
static void unix_stop_timer(struct qemu_alarm_timer *t)
{
struct itimerval itv;
memset(&itv, 0, sizeof(itv));
setitimer(ITIMER_REAL, &itv, NULL);
}
#endif /* !defined(_WIN32) */
#ifdef _WIN32
static MMRESULT mm_timer;
static TIMECAPS mm_tc;
static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
DWORD_PTR dwUser, DWORD_PTR dw1,
DWORD_PTR dw2)
{
struct qemu_alarm_timer *t = alarm_timer;
if (!t) {
return;
}
t->expired = true;
t->pending = true;
qemu_notify_event();
}
static int mm_start_timer(struct qemu_alarm_timer *t)
{
timeGetDevCaps(&mm_tc, sizeof(mm_tc));
timeBeginPeriod(mm_tc.wPeriodMin);
mm_timer = timeSetEvent(mm_tc.wPeriodMin, /* interval (ms) */
mm_tc.wPeriodMin, /* resolution */
mm_alarm_handler, /* function */
(DWORD_PTR)t, /* parameter */
TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
if (!mm_timer) {
fprintf(stderr, "Failed to initialize win32 alarm timer\n");
timeEndPeriod(mm_tc.wPeriodMin);
return -1;
}
return 0;
}
static void mm_stop_timer(struct qemu_alarm_timer *t)
{
timeKillEvent(mm_timer);
timeEndPeriod(mm_tc.wPeriodMin);
}
static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
{
int64_t nearest_delta_ms = delta / 1000000;
if (nearest_delta_ms < mm_tc.wPeriodMin) {
nearest_delta_ms = mm_tc.wPeriodMin;
} else if (nearest_delta_ms > mm_tc.wPeriodMax) {
nearest_delta_ms = mm_tc.wPeriodMax;
}
timeKillEvent(mm_timer);
mm_timer = timeSetEvent((UINT)nearest_delta_ms,
mm_tc.wPeriodMin,
mm_alarm_handler,
(DWORD_PTR)t,
TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
if (!mm_timer) {
fprintf(stderr, "Failed to re-arm win32 alarm timer\n");
timeEndPeriod(mm_tc.wPeriodMin);
exit(1);
}
}
static int win32_start_timer(struct qemu_alarm_timer *t)
{
HANDLE hTimer;
BOOLEAN success;
/* If you call ChangeTimerQueueTimer on a one-shot timer (its period
is zero) that has already expired, the timer is not updated. Since
creating a new timer is relatively expensive, set a bogus one-hour
interval in the dynticks case. */
success = CreateTimerQueueTimer(&hTimer,
NULL,
host_alarm_handler,
t,
1,
3600000,
WT_EXECUTEINTIMERTHREAD);
if (!success) {
fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
GetLastError());
return -1;
}
t->timer = hTimer;
return 0;
}
static void win32_stop_timer(struct qemu_alarm_timer *t)
{
HANDLE hTimer = t->timer;
if (hTimer) {
DeleteTimerQueueTimer(NULL, hTimer, NULL);
}
}
static void win32_rearm_timer(struct qemu_alarm_timer *t,
int64_t nearest_delta_ns)
{
HANDLE hTimer = t->timer;
int64_t nearest_delta_ms;
BOOLEAN success;
nearest_delta_ms = nearest_delta_ns / 1000000;
if (nearest_delta_ms < 1) {
nearest_delta_ms = 1;
}
/* ULONG_MAX can be 32 bit */
if (nearest_delta_ms > ULONG_MAX) {
nearest_delta_ms = ULONG_MAX;
}
success = ChangeTimerQueueTimer(NULL,
hTimer,
(unsigned long) nearest_delta_ms,
3600000);
if (!success) {
fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
GetLastError());
exit(-1);
}
}
#endif /* _WIN32 */
static void quit_timers(void)
{
struct qemu_alarm_timer *t = alarm_timer;
alarm_timer = NULL;
t->stop(t);
}
int init_timer_alarm(void)
{
struct qemu_alarm_timer *t = NULL;
int i, err = -1;
for (i = 0; alarm_timers[i].name; i++) {
t = &alarm_timers[i];
err = t->start(t);
if (!err)
break;
}
if (err) {
err = -ENOENT;
goto fail;
}
atexit(quit_timers);
alarm_timer = t;
return 0;
fail:
return err;
}
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