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throttle: support read-only and write-only

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Only one direction is necessary in several scenarios:
- a read-only disk
- operations on a device are considered as *write* only. For example,
  encrypt/decrypt/sign/verify operations on a cryptodev use a single
  *write* timer(read timer callback is defined, but never invoked).

Allow a single direction in throttle, this reduces memory, and uplayer
does not need a dummy callback any more.

Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Message-Id: <20230728022006.1098509-4-pizhenwei@bytedance.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
This commit is contained in:
zhenwei pi 2023-07-28 10:20:00 +08:00 committed by Hanna Czenczek
parent 1322f63df5
commit d85b08c6e2
1 changed files with 28 additions and 14 deletions
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42
util/throttle.c
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@ -199,12 +199,15 @@ static bool throttle_compute_timer(ThrottleState *ts,
void throttle_timers_attach_aio_context(ThrottleTimers *tt,
AioContext *new_context)
{
tt->timers[THROTTLE_READ] =
aio_timer_new(new_context, tt->clock_type, SCALE_NS,
tt->timer_cb[THROTTLE_READ], tt->timer_opaque);
tt->timers[THROTTLE_WRITE] =
aio_timer_new(new_context, tt->clock_type, SCALE_NS,
tt->timer_cb[THROTTLE_WRITE], tt->timer_opaque);
ThrottleDirection dir;
for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
if (tt->timer_cb[dir]) {
tt->timers[dir] =
aio_timer_new(new_context, tt->clock_type, SCALE_NS,
tt->timer_cb[dir], tt->timer_opaque);
}
}
}
/*
@ -235,6 +238,7 @@ void throttle_timers_init(ThrottleTimers *tt,
QEMUTimerCB *write_timer_cb,
void *timer_opaque)
{
assert(read_timer_cb || write_timer_cb);
memset(tt, 0, sizeof(ThrottleTimers));
tt->clock_type = clock_type;
@ -247,7 +251,9 @@ void throttle_timers_init(ThrottleTimers *tt,
/* destroy a timer */
static void throttle_timer_destroy(QEMUTimer **timer)
{
assert(*timer != NULL);
if (*timer == NULL) {
return;
}
timer_free(*timer);
*timer = NULL;
@ -256,10 +262,10 @@ static void throttle_timer_destroy(QEMUTimer **timer)
/* Remove timers from event loop */
void throttle_timers_detach_aio_context(ThrottleTimers *tt)
{
int i;
ThrottleDirection dir;
for (i = 0; i < THROTTLE_MAX; i++) {
throttle_timer_destroy(&tt->timers[i]);
for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
throttle_timer_destroy(&tt->timers[dir]);
}
}
@ -272,8 +278,12 @@ void throttle_timers_destroy(ThrottleTimers *tt)
/* is any throttling timer configured */
bool throttle_timers_are_initialized(ThrottleTimers *tt)
{
if (tt->timers[0]) {
return true;
ThrottleDirection dir;
for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
if (tt->timers[dir]) {
return true;
}
}
return false;
@ -424,8 +434,12 @@ bool throttle_schedule_timer(ThrottleState *ts,
{
int64_t now = qemu_clock_get_ns(tt->clock_type);
int64_t next_timestamp;
QEMUTimer *timer;
bool must_wait;
timer = is_write ? tt->timers[THROTTLE_WRITE] : tt->timers[THROTTLE_READ];
assert(timer);
must_wait = throttle_compute_timer(ts,
is_write,
now,
@ -437,12 +451,12 @@ bool throttle_schedule_timer(ThrottleState *ts,
}
/* request throttled and timer pending -> do nothing */
if (timer_pending(tt->timers[is_write])) {
if (timer_pending(timer)) {
return true;
}
/* request throttled and timer not pending -> arm timer */
timer_mod(tt->timers[is_write], next_timestamp);
timer_mod(timer, next_timestamp);
return true;
}