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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>
118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/*
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* Linux AIO request queue
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*
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* Copyright 2012 IBM, Corp.
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* Copyright 2012 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "hw/dataplane/ioq.h"
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void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs)
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{
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int rc;
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ioq->fd = fd;
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ioq->max_reqs = max_reqs;
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memset(&ioq->io_ctx, 0, sizeof ioq->io_ctx);
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rc = io_setup(max_reqs, &ioq->io_ctx);
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if (rc != 0) {
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fprintf(stderr, "ioq io_setup failed %d\n", rc);
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exit(1);
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}
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rc = event_notifier_init(&ioq->io_notifier, 0);
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if (rc != 0) {
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fprintf(stderr, "ioq io event notifier creation failed %d\n", rc);
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exit(1);
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}
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ioq->freelist = g_malloc0(sizeof ioq->freelist[0] * max_reqs);
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ioq->freelist_idx = 0;
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ioq->queue = g_malloc0(sizeof ioq->queue[0] * max_reqs);
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ioq->queue_idx = 0;
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}
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void ioq_cleanup(IOQueue *ioq)
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{
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g_free(ioq->freelist);
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g_free(ioq->queue);
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event_notifier_cleanup(&ioq->io_notifier);
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io_destroy(ioq->io_ctx);
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}
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EventNotifier *ioq_get_notifier(IOQueue *ioq)
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{
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return &ioq->io_notifier;
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}
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struct iocb *ioq_get_iocb(IOQueue *ioq)
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{
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/* Underflow cannot happen since ioq is sized for max_reqs */
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assert(ioq->freelist_idx != 0);
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struct iocb *iocb = ioq->freelist[--ioq->freelist_idx];
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ioq->queue[ioq->queue_idx++] = iocb;
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return iocb;
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}
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void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb)
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{
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/* Overflow cannot happen since ioq is sized for max_reqs */
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assert(ioq->freelist_idx != ioq->max_reqs);
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ioq->freelist[ioq->freelist_idx++] = iocb;
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}
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struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
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unsigned int count, long long offset)
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{
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struct iocb *iocb = ioq_get_iocb(ioq);
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if (read) {
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io_prep_preadv(iocb, ioq->fd, iov, count, offset);
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} else {
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io_prep_pwritev(iocb, ioq->fd, iov, count, offset);
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}
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io_set_eventfd(iocb, event_notifier_get_fd(&ioq->io_notifier));
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return iocb;
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}
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int ioq_submit(IOQueue *ioq)
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{
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int rc = io_submit(ioq->io_ctx, ioq->queue_idx, ioq->queue);
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ioq->queue_idx = 0; /* reset */
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return rc;
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}
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int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
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void *opaque)
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{
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struct io_event events[ioq->max_reqs];
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int nevents, i;
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do {
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nevents = io_getevents(ioq->io_ctx, 0, ioq->max_reqs, events, NULL);
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} while (nevents < 0 && errno == EINTR);
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if (nevents < 0) {
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return nevents;
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}
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for (i = 0; i < nevents; i++) {
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ssize_t ret = ((uint64_t)events[i].res2 << 32) | events[i].res;
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completion(events[i].obj, ret, opaque);
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ioq_put_iocb(ioq, events[i].obj);
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}
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return nevents;
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}
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