coroutine: make pool size dynamic
Allow coroutine users to adjust the pool size. For example, if the guest has multiple emulated disk drives we should keep around more coroutines. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
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@ -223,4 +223,15 @@ void coroutine_fn co_aio_sleep_ns(AioContext *ctx, QEMUClockType type,
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* Note that this function clobbers the handlers for the file descriptor.
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* Note that this function clobbers the handlers for the file descriptor.
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*/
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*/
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void coroutine_fn yield_until_fd_readable(int fd);
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void coroutine_fn yield_until_fd_readable(int fd);
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/**
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* Add or subtract from the coroutine pool size
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*
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* The coroutine implementation keeps a pool of coroutines to be reused by
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* qemu_coroutine_create(). This makes coroutine creation cheap. Heavy
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* coroutine users should call this to reserve pool space. Call it again with
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* a negative number to release pool space.
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*/
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void qemu_coroutine_adjust_pool_size(int n);
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#endif /* QEMU_COROUTINE_H */
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#endif /* QEMU_COROUTINE_H */
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@ -19,14 +19,14 @@
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#include "block/coroutine_int.h"
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#include "block/coroutine_int.h"
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enum {
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enum {
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/* Maximum free pool size prevents holding too many freed coroutines */
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POOL_DEFAULT_SIZE = 64,
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POOL_MAX_SIZE = 64,
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};
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};
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/** Free list to speed up creation */
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/** Free list to speed up creation */
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static QemuMutex pool_lock;
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static QemuMutex pool_lock;
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static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
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static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
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static unsigned int pool_size;
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static unsigned int pool_size;
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static unsigned int pool_max_size = POOL_DEFAULT_SIZE;
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Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
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Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
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{
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{
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@ -55,7 +55,7 @@ static void coroutine_delete(Coroutine *co)
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{
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{
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if (CONFIG_COROUTINE_POOL) {
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if (CONFIG_COROUTINE_POOL) {
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qemu_mutex_lock(&pool_lock);
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qemu_mutex_lock(&pool_lock);
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if (pool_size < POOL_MAX_SIZE) {
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if (pool_size < pool_max_size) {
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QSLIST_INSERT_HEAD(&pool, co, pool_next);
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QSLIST_INSERT_HEAD(&pool, co, pool_next);
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co->caller = NULL;
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co->caller = NULL;
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pool_size++;
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pool_size++;
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@ -137,3 +137,23 @@ void coroutine_fn qemu_coroutine_yield(void)
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self->caller = NULL;
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self->caller = NULL;
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coroutine_swap(self, to);
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coroutine_swap(self, to);
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}
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}
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void qemu_coroutine_adjust_pool_size(int n)
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{
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qemu_mutex_lock(&pool_lock);
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pool_max_size += n;
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/* Callers should never take away more than they added */
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assert(pool_max_size >= POOL_DEFAULT_SIZE);
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/* Trim oversized pool down to new max */
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while (pool_size > pool_max_size) {
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Coroutine *co = QSLIST_FIRST(&pool);
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QSLIST_REMOVE_HEAD(&pool, pool_next);
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pool_size--;
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qemu_coroutine_delete(co);
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}
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qemu_mutex_unlock(&pool_lock);
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}
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