3e9ec52171
The IOQueue has a pool of iocb structs and a function to add new read/write requests. Multiple requests can be added before calling the submit function to actually tell the host kernel to begin I/O. This allows callers to batch requests and submit them in one go. The actual I/O is performed using Linux AIO. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/*
|
|
* Linux AIO request queue
|
|
*
|
|
* Copyright 2012 IBM, Corp.
|
|
* Copyright 2012 Red Hat, Inc. and/or its affiliates
|
|
*
|
|
* Authors:
|
|
* Stefan Hajnoczi <stefanha@redhat.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2 or later.
|
|
* See the COPYING file in the top-level directory.
|
|
*
|
|
*/
|
|
|
|
#ifndef IOQ_H
|
|
#define IOQ_H
|
|
|
|
#include <libaio.h>
|
|
#include "qemu/event_notifier.h"
|
|
|
|
typedef struct {
|
|
int fd; /* file descriptor */
|
|
unsigned int max_reqs; /* max length of freelist and queue */
|
|
|
|
io_context_t io_ctx; /* Linux AIO context */
|
|
EventNotifier io_notifier; /* Linux AIO eventfd */
|
|
|
|
/* Requests can complete in any order so a free list is necessary to manage
|
|
* available iocbs.
|
|
*/
|
|
struct iocb **freelist; /* free iocbs */
|
|
unsigned int freelist_idx;
|
|
|
|
/* Multiple requests are queued up before submitting them all in one go */
|
|
struct iocb **queue; /* queued iocbs */
|
|
unsigned int queue_idx;
|
|
} IOQueue;
|
|
|
|
void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs);
|
|
void ioq_cleanup(IOQueue *ioq);
|
|
EventNotifier *ioq_get_notifier(IOQueue *ioq);
|
|
struct iocb *ioq_get_iocb(IOQueue *ioq);
|
|
void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb);
|
|
struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
|
|
unsigned int count, long long offset);
|
|
int ioq_submit(IOQueue *ioq);
|
|
|
|
static inline unsigned int ioq_num_queued(IOQueue *ioq)
|
|
{
|
|
return ioq->queue_idx;
|
|
}
|
|
|
|
typedef void IOQueueCompletion(struct iocb *iocb, ssize_t ret, void *opaque);
|
|
int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
|
|
void *opaque);
|
|
|
|
#endif /* IOQ_H */
|