Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-07-02' into staging

[mirror_qemu.git] / block / throttle-groups.c

diff --git a/block/throttle-groups.c b/block/throttle-groups.c
index 2587f19ca33f76c96dd2d38535f4b2f3165b2a9a..a5a20379244e20a7808b7d106972e36d29cbb60f 100644 (file)
--- a/block/throttle-groups.c
+++ b/block/throttle-groups.c
@@ -30,12 +30,13 @@
 #include "qemu/thread.h"
 #include "sysemu/qtest.h"
 #include "qapi/error.h"
-#include "qapi-visit.h"
+#include "qapi/qapi-visit-block-core.h"
 #include "qom/object.h"
 #include "qom/object_interfaces.h"
 
 static void throttle_group_obj_init(Object *obj);
 static void throttle_group_obj_complete(UserCreatable *obj, Error **errp);
+static void timer_cb(ThrottleGroupMember *tgm, bool is_write);
 
 /* The ThrottleGroup structure (with its ThrottleState) is shared
  * among different ThrottleGroupMembers and it's independent from
@@ -221,6 +222,15 @@ static ThrottleGroupMember *next_throttle_token(ThrottleGroupMember *tgm,
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
     ThrottleGroupMember *token, *start;
 
+    /* If this member has its I/O limits disabled then it means that
+     * it's being drained. Skip the round-robin search and return tgm
+     * immediately if it has pending requests. Otherwise we could be
+     * forcing it to wait for other member's throttled requests. */
+    if (tgm_has_pending_reqs(tgm, is_write) &&
+        atomic_read(&tgm->io_limits_disabled)) {
+        return tgm;
+    }
+
     start = token = tg->tokens[is_write];
 
     /* get next bs round in round robin style */
@@ -405,6 +415,9 @@ static void coroutine_fn throttle_group_restart_queue_entry(void *opaque)
     }
 
     g_free(data);
+
+    atomic_dec(&tgm->restart_pending);
+    aio_wait_kick();
 }
 
 static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write)
@@ -415,15 +428,33 @@ static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write
     rd->tgm = tgm;
     rd->is_write = is_write;
 
+    /* This function is called when a timer is fired or when
+     * throttle_group_restart_tgm() is called. Either way, there can
+     * be no timer pending on this tgm at this point */
+    assert(!timer_pending(tgm->throttle_timers.timers[is_write]));
+
+    atomic_inc(&tgm->restart_pending);
+
     co = qemu_coroutine_create(throttle_group_restart_queue_entry, rd);
     aio_co_enter(tgm->aio_context, co);
 }
 
 void throttle_group_restart_tgm(ThrottleGroupMember *tgm)
 {
+    int i;
+
     if (tgm->throttle_state) {
-        throttle_group_restart_queue(tgm, 0);
-        throttle_group_restart_queue(tgm, 1);
+        for (i = 0; i < 2; i++) {
+            QEMUTimer *t = tgm->throttle_timers.timers[i];
+            if (timer_pending(t)) {
+                /* If there's a pending timer on this tgm, fire it now */
+                timer_del(t);
+                timer_cb(tgm, i);
+            } else {
+                /* Else run the next request from the queue manually */
+                throttle_group_restart_queue(tgm, i);
+            }
+        }
     }
 }
 
@@ -512,6 +543,7 @@ void throttle_group_register_tgm(ThrottleGroupMember *tgm,
 
     tgm->throttle_state = ts;
     tgm->aio_context = ctx;
+    atomic_set(&tgm->restart_pending, 0);
 
     qemu_mutex_lock(&tg->lock);
     /* If the ThrottleGroup is new set this ThrottleGroupMember as the token */
@@ -558,12 +590,14 @@ void throttle_group_unregister_tgm(ThrottleGroupMember *tgm)
         return;
     }
 
-    assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0);
-    assert(qemu_co_queue_empty(&tgm->throttled_reqs[0]));
-    assert(qemu_co_queue_empty(&tgm->throttled_reqs[1]));
+    /* Wait for throttle_group_restart_queue_entry() coroutines to finish */
+    AIO_WAIT_WHILE(tgm->aio_context, atomic_read(&tgm->restart_pending) > 0);
 
     qemu_mutex_lock(&tg->lock);
     for (i = 0; i < 2; i++) {
+        assert(tgm->pending_reqs[i] == 0);
+        assert(qemu_co_queue_empty(&tgm->throttled_reqs[i]));
+        assert(!timer_pending(tgm->throttle_timers.timers[i]));
         if (tg->tokens[i] == tgm) {
             token = throttle_group_next_tgm(tgm);
             /* Take care of the case where this is the last tgm in the group */
@@ -593,13 +627,25 @@ void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
 
 void throttle_group_detach_aio_context(ThrottleGroupMember *tgm)
 {
+    ThrottleGroup *tg = container_of(tgm->throttle_state, ThrottleGroup, ts);
     ThrottleTimers *tt = &tgm->throttle_timers;
+    int i;
 
     /* Requests must have been drained */
     assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0);
     assert(qemu_co_queue_empty(&tgm->throttled_reqs[0]));
     assert(qemu_co_queue_empty(&tgm->throttled_reqs[1]));
 
+    /* Kick off next ThrottleGroupMember, if necessary */
+    qemu_mutex_lock(&tg->lock);
+    for (i = 0; i < 2; i++) {
+        if (timer_pending(tt->timers[i])) {
+            tg->any_timer_armed[i] = false;
+            schedule_next_request(tgm, i);
+        }
+    }
+    qemu_mutex_unlock(&tg->lock);
+
     throttle_timers_detach_aio_context(tt);
     tgm->aio_context = NULL;
 }