x86: pcihp: acpi: prepare slot ignore rule to work with self describing bridges
[qemu.git] / util / qemu-coroutine.c
blob849452369201bb5e7e9c2380c09bf28afa3e563e
1 /*
2 * QEMU coroutines
4 * Copyright IBM, Corp. 2011
6 * Authors:
7 * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
8 * Kevin Wolf <kwolf@redhat.com>
10 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
11 * See the COPYING.LIB file in the top-level directory.
15 #include "qemu/osdep.h"
16 #include "trace.h"
17 #include "qemu/thread.h"
18 #include "qemu/atomic.h"
19 #include "qemu/coroutine_int.h"
20 #include "qemu/coroutine-tls.h"
21 #include "block/aio.h"
23 /**
24 * The minimal batch size is always 64, coroutines from the release_pool are
25 * reused as soon as there are 64 coroutines in it. The maximum pool size starts
26 * with 64 and is increased on demand so that coroutines are not deleted even if
27 * they are not immediately reused.
29 enum {
30 POOL_MIN_BATCH_SIZE = 64,
31 POOL_INITIAL_MAX_SIZE = 64,
34 /** Free list to speed up creation */
35 static QSLIST_HEAD(, Coroutine) release_pool = QSLIST_HEAD_INITIALIZER(pool);
36 static unsigned int pool_max_size = POOL_INITIAL_MAX_SIZE;
37 static unsigned int release_pool_size;
39 typedef QSLIST_HEAD(, Coroutine) CoroutineQSList;
40 QEMU_DEFINE_STATIC_CO_TLS(CoroutineQSList, alloc_pool);
41 QEMU_DEFINE_STATIC_CO_TLS(unsigned int, alloc_pool_size);
42 QEMU_DEFINE_STATIC_CO_TLS(Notifier, coroutine_pool_cleanup_notifier);
44 static void coroutine_pool_cleanup(Notifier *n, void *value)
46 Coroutine *co;
47 Coroutine *tmp;
48 CoroutineQSList *alloc_pool = get_ptr_alloc_pool();
50 QSLIST_FOREACH_SAFE(co, alloc_pool, pool_next, tmp) {
51 QSLIST_REMOVE_HEAD(alloc_pool, pool_next);
52 qemu_coroutine_delete(co);
56 Coroutine *qemu_coroutine_create(CoroutineEntry *entry, void *opaque)
58 Coroutine *co = NULL;
60 if (CONFIG_COROUTINE_POOL) {
61 CoroutineQSList *alloc_pool = get_ptr_alloc_pool();
63 co = QSLIST_FIRST(alloc_pool);
64 if (!co) {
65 if (release_pool_size > POOL_MIN_BATCH_SIZE) {
66 /* Slow path; a good place to register the destructor, too. */
67 Notifier *notifier = get_ptr_coroutine_pool_cleanup_notifier();
68 if (!notifier->notify) {
69 notifier->notify = coroutine_pool_cleanup;
70 qemu_thread_atexit_add(notifier);
73 /* This is not exact; there could be a little skew between
74 * release_pool_size and the actual size of release_pool. But
75 * it is just a heuristic, it does not need to be perfect.
77 set_alloc_pool_size(qatomic_xchg(&release_pool_size, 0));
78 QSLIST_MOVE_ATOMIC(alloc_pool, &release_pool);
79 co = QSLIST_FIRST(alloc_pool);
82 if (co) {
83 QSLIST_REMOVE_HEAD(alloc_pool, pool_next);
84 set_alloc_pool_size(get_alloc_pool_size() - 1);
88 if (!co) {
89 co = qemu_coroutine_new();
92 co->entry = entry;
93 co->entry_arg = opaque;
94 QSIMPLEQ_INIT(&co->co_queue_wakeup);
95 return co;
98 static void coroutine_delete(Coroutine *co)
100 co->caller = NULL;
102 if (CONFIG_COROUTINE_POOL) {
103 if (release_pool_size < qatomic_read(&pool_max_size) * 2) {
104 QSLIST_INSERT_HEAD_ATOMIC(&release_pool, co, pool_next);
105 qatomic_inc(&release_pool_size);
106 return;
108 if (get_alloc_pool_size() < qatomic_read(&pool_max_size)) {
109 QSLIST_INSERT_HEAD(get_ptr_alloc_pool(), co, pool_next);
110 set_alloc_pool_size(get_alloc_pool_size() + 1);
111 return;
115 qemu_coroutine_delete(co);
118 void qemu_aio_coroutine_enter(AioContext *ctx, Coroutine *co)
120 QSIMPLEQ_HEAD(, Coroutine) pending = QSIMPLEQ_HEAD_INITIALIZER(pending);
121 Coroutine *from = qemu_coroutine_self();
123 QSIMPLEQ_INSERT_TAIL(&pending, co, co_queue_next);
125 /* Run co and any queued coroutines */
126 while (!QSIMPLEQ_EMPTY(&pending)) {
127 Coroutine *to = QSIMPLEQ_FIRST(&pending);
128 CoroutineAction ret;
130 /* Cannot rely on the read barrier for to in aio_co_wake(), as there are
131 * callers outside of aio_co_wake() */
132 const char *scheduled = qatomic_mb_read(&to->scheduled);
134 QSIMPLEQ_REMOVE_HEAD(&pending, co_queue_next);
136 trace_qemu_aio_coroutine_enter(ctx, from, to, to->entry_arg);
138 /* if the Coroutine has already been scheduled, entering it again will
139 * cause us to enter it twice, potentially even after the coroutine has
140 * been deleted */
141 if (scheduled) {
142 fprintf(stderr,
143 "%s: Co-routine was already scheduled in '%s'\n",
144 __func__, scheduled);
145 abort();
148 if (to->caller) {
149 fprintf(stderr, "Co-routine re-entered recursively\n");
150 abort();
153 to->caller = from;
154 to->ctx = ctx;
156 /* Store to->ctx before anything that stores to. Matches
157 * barrier in aio_co_wake and qemu_co_mutex_wake.
159 smp_wmb();
161 ret = qemu_coroutine_switch(from, to, COROUTINE_ENTER);
163 /* Queued coroutines are run depth-first; previously pending coroutines
164 * run after those queued more recently.
166 QSIMPLEQ_PREPEND(&pending, &to->co_queue_wakeup);
168 switch (ret) {
169 case COROUTINE_YIELD:
170 break;
171 case COROUTINE_TERMINATE:
172 assert(!to->locks_held);
173 trace_qemu_coroutine_terminate(to);
174 coroutine_delete(to);
175 break;
176 default:
177 abort();
182 void qemu_coroutine_enter(Coroutine *co)
184 qemu_aio_coroutine_enter(qemu_get_current_aio_context(), co);
187 void qemu_coroutine_enter_if_inactive(Coroutine *co)
189 if (!qemu_coroutine_entered(co)) {
190 qemu_coroutine_enter(co);
194 void coroutine_fn qemu_coroutine_yield(void)
196 Coroutine *self = qemu_coroutine_self();
197 Coroutine *to = self->caller;
199 trace_qemu_coroutine_yield(self, to);
201 if (!to) {
202 fprintf(stderr, "Co-routine is yielding to no one\n");
203 abort();
206 self->caller = NULL;
207 qemu_coroutine_switch(self, to, COROUTINE_YIELD);
210 bool qemu_coroutine_entered(Coroutine *co)
212 return co->caller;
215 AioContext *qemu_coroutine_get_aio_context(Coroutine *co)
217 return co->ctx;
220 void qemu_coroutine_inc_pool_size(unsigned int additional_pool_size)
222 qatomic_add(&pool_max_size, additional_pool_size);
225 void qemu_coroutine_dec_pool_size(unsigned int removing_pool_size)
227 qatomic_sub(&pool_max_size, removing_pool_size);