1 /*
2  * QEMU block throttling group infrastructure
3  *
4  * Copyright (C) Nodalink, EURL. 2014
5  * Copyright (C) Igalia, S.L. 2015
6  *
7  * Authors:
8  *   Benoît Canet <benoit.canet@nodalink.com>
9  *   Alberto Garcia <berto@igalia.com>
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License as
13  * published by the Free Software Foundation; either version 2 or
14  * (at your option) version 3 of the License.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, see <http://www.gnu.org/licenses/>.
23  */
24 
25 #ifndef THROTTLE_GROUPS_H
26 #define THROTTLE_GROUPS_H
27 
28 #include "qemu/coroutine.h"
29 #include "qemu/throttle.h"
30 #include "qom/object.h"
31 
32 /* The ThrottleGroupMember structure indicates membership in a ThrottleGroup
33  * and holds related data.
34  */
35 
36 typedef struct ThrottleGroupMember {
37     AioContext   *aio_context;
38     /* throttled_reqs_lock protects the CoQueues for throttled requests.  */
39     CoMutex      throttled_reqs_lock;
40     CoQueue      throttled_reqs[2];
41 
42     /* Nonzero if the I/O limits are currently being ignored; generally
43      * it is zero.  Accessed with atomic operations.
44      */
45     unsigned int io_limits_disabled;
46 
47     /* Number of pending throttle_group_restart_queue_entry() coroutines.
48      * Accessed with atomic operations.
49      */
50     unsigned int restart_pending;
51 
52     /* The following fields are protected by the ThrottleGroup lock.
53      * See the ThrottleGroup documentation for details.
54      * throttle_state tells us if I/O limits are configured. */
55     ThrottleState *throttle_state;
56     ThrottleTimers throttle_timers;
57     unsigned       pending_reqs[2];
58     QLIST_ENTRY(ThrottleGroupMember) round_robin;
59 
60 } ThrottleGroupMember;
61 
62 #define TYPE_THROTTLE_GROUP "throttle-group"
63 OBJECT_DECLARE_SIMPLE_TYPE(ThrottleGroup, THROTTLE_GROUP)
64 
65 const char *throttle_group_get_name(ThrottleGroupMember *tgm);
66 
67 ThrottleState *throttle_group_incref(const char *name);
68 void throttle_group_unref(ThrottleState *ts);
69 
70 void throttle_group_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
71 void throttle_group_get_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
72 
73 void throttle_group_register_tgm(ThrottleGroupMember *tgm,
74                                 const char *groupname,
75                                 AioContext *ctx);
76 void throttle_group_unregister_tgm(ThrottleGroupMember *tgm);
77 void throttle_group_restart_tgm(ThrottleGroupMember *tgm);
78 
79 void coroutine_fn throttle_group_co_io_limits_intercept(ThrottleGroupMember *tgm,
80                                                         int64_t bytes,
81                                                         bool is_write);
82 void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
83                                        AioContext *new_context);
84 void throttle_group_detach_aio_context(ThrottleGroupMember *tgm);
85 /*
86  * throttle_group_exists() must be called under the global
87  * mutex.
88  */
89 bool throttle_group_exists(const char *name);
90 
91 #endif
92