qemu-patch-raspberry4/util/aio-posix.h
Stefan Hajnoczi 73fd282e7b aio-posix: add io_uring fd monitoring implementation
The recent Linux io_uring API has several advantages over ppoll(2) and
epoll(2).  Details are given in the source code.

Add an io_uring implementation and make it the default on Linux.
Performance is the same as with epoll(7) but later patches add
optimizations that take advantage of io_uring.

It is necessary to change how aio_set_fd_handler() deals with deleting
AioHandlers since removing monitored file descriptors is asynchronous in
io_uring.  fdmon_io_uring_remove() marks the AioHandler deleted and
aio_set_fd_handler() will let it handle deletion in that case.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20200305170806.1313245-6-stefanha@redhat.com
Message-Id: <20200305170806.1313245-6-stefanha@redhat.com>
2020-03-09 16:41:31 +00:00

80 lines
1.9 KiB
C

/*
* AioContext POSIX event loop implementation internal APIs
*
* Copyright IBM, Corp. 2008
* Copyright Red Hat, Inc. 2020
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#ifndef AIO_POSIX_H
#define AIO_POSIX_H
#include "block/aio.h"
struct AioHandler {
GPollFD pfd;
IOHandler *io_read;
IOHandler *io_write;
AioPollFn *io_poll;
IOHandler *io_poll_begin;
IOHandler *io_poll_end;
void *opaque;
QLIST_ENTRY(AioHandler) node;
QLIST_ENTRY(AioHandler) node_ready; /* only used during aio_poll() */
QLIST_ENTRY(AioHandler) node_deleted;
#ifdef CONFIG_LINUX_IO_URING
QSLIST_ENTRY(AioHandler) node_submitted;
unsigned flags; /* see fdmon-io_uring.c */
#endif
bool is_external;
};
/* Add a handler to a ready list */
void aio_add_ready_handler(AioHandlerList *ready_list, AioHandler *node,
int revents);
extern const FDMonOps fdmon_poll_ops;
#ifdef CONFIG_EPOLL_CREATE1
bool fdmon_epoll_try_upgrade(AioContext *ctx, unsigned npfd);
void fdmon_epoll_setup(AioContext *ctx);
void fdmon_epoll_disable(AioContext *ctx);
#else
static inline bool fdmon_epoll_try_upgrade(AioContext *ctx, unsigned npfd)
{
return false;
}
static inline void fdmon_epoll_setup(AioContext *ctx)
{
}
static inline void fdmon_epoll_disable(AioContext *ctx)
{
}
#endif /* !CONFIG_EPOLL_CREATE1 */
#ifdef CONFIG_LINUX_IO_URING
bool fdmon_io_uring_setup(AioContext *ctx);
void fdmon_io_uring_destroy(AioContext *ctx);
#else
static inline bool fdmon_io_uring_setup(AioContext *ctx)
{
return false;
}
static inline void fdmon_io_uring_destroy(AioContext *ctx)
{
}
#endif /* !CONFIG_LINUX_IO_URING */
#endif /* AIO_POSIX_H */