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aio-posix: split poll check from ready handler

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Adaptive polling measures the execution time of the polling check plus
handlers called when a polled event becomes ready. Handlers can take a
significant amount of time, making it look like polling was running for
a long time when in fact the event handler was running for a long time.

For example, on Linux the io_submit(2) syscall invoked when a virtio-blk
device's virtqueue becomes ready can take 10s of microseconds. This
can exceed the default polling interval (32 microseconds) and cause
adaptive polling to stop polling.

By excluding the handler's execution time from the polling check we make
the adaptive polling calculation more accurate. As a result, the event
loop now stays in polling mode where previously it would have fallen
back to file descriptor monitoring.

The following data was collected with virtio-blk num-queues=2
event_idx=off using an IOThread. Before:

168k IOPS, IOThread syscalls:

  9837.115 ( 0.020 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 16, iocbpp: 0x7fcb9f937db0)    = 16
  9837.158 ( 0.002 ms): IO iothread1/620155 write(fd: 103, buf: 0x556a2ef71b88, count: 8)                         = 8
  9837.161 ( 0.001 ms): IO iothread1/620155 write(fd: 104, buf: 0x556a2ef71b88, count: 8)                         = 8
  9837.163 ( 0.001 ms): IO iothread1/620155 ppoll(ufds: 0x7fcb90002800, nfds: 4, tsp: 0x7fcb9f1342d0, sigsetsize: 8) = 3
  9837.164 ( 0.001 ms): IO iothread1/620155 read(fd: 107, buf: 0x7fcb9f939cc0, count: 512)                        = 8
  9837.174 ( 0.001 ms): IO iothread1/620155 read(fd: 105, buf: 0x7fcb9f939cc0, count: 512)                        = 8
  9837.176 ( 0.001 ms): IO iothread1/620155 read(fd: 106, buf: 0x7fcb9f939cc0, count: 512)                        = 8
  9837.209 ( 0.035 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 32, iocbpp: 0x7fca7d0cebe0)    = 32

174k IOPS (+3.6%), IOThread syscalls:

  9809.566 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0cdd62be0)    = 32
  9809.625 ( 0.001 ms): IO iothread1/623061 write(fd: 103, buf: 0x5647cfba5f58, count: 8)                         = 8
  9809.627 ( 0.002 ms): IO iothread1/623061 write(fd: 104, buf: 0x5647cfba5f58, count: 8)                         = 8
  9809.663 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0d0388b50)    = 32

Notice that ppoll(2) and eventfd read(2) syscalls are eliminated because
the IOThread stays in polling mode instead of falling back to file
descriptor monitoring.

As usual, polling is not implemented on Windows so this patch ignores
the new io_poll_read() callback in aio-win32.c.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20211207132336.36627-2-stefanha@redhat.com

[Fixed up aio_set_event_notifier() calls in
tests/unit/test-fdmon-epoll.c added after this series was queued.
--Stefan]

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2021-12-07 13:23:31 +00:00
parent 91f5f7a5df
commit 826cc32423
25 changed files with 193 additions and 104 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
block/curl.c
View File

@ -125,7 +125,7 @@ static gboolean curl_drop_socket(void *key, void *value, void *opaque)
BDRVCURLState *s = socket->s;
aio_set_fd_handler(s->aio_context, socket->fd, false,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
return true;
}
@ -173,19 +173,20 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
switch (action) {
case CURL_POLL_IN:
aio_set_fd_handler(s->aio_context, fd, false,
curl_multi_do, NULL, NULL, socket);
curl_multi_do, NULL, NULL, NULL, socket);
break;
case CURL_POLL_OUT:
aio_set_fd_handler(s->aio_context, fd, false,
NULL, curl_multi_do, NULL, socket);
NULL, curl_multi_do, NULL, NULL, socket);
break;
case CURL_POLL_INOUT:
aio_set_fd_handler(s->aio_context, fd, false,
curl_multi_do, curl_multi_do, NULL, socket);
curl_multi_do, curl_multi_do,
NULL, NULL, socket);
break;
case CURL_POLL_REMOVE:
aio_set_fd_handler(s->aio_context, fd, false,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
break;
}

4
block/export/fuse.c
View File

@ -223,7 +223,7 @@ static int setup_fuse_export(FuseExport *exp, const char *mountpoint,
aio_set_fd_handler(exp->common.ctx,
fuse_session_fd(exp->fuse_session), true,
read_from_fuse_export, NULL, NULL, exp);
read_from_fuse_export, NULL, NULL, NULL, exp);
exp->fd_handler_set_up = true;
return 0;
@ -267,7 +267,7 @@ static void fuse_export_shutdown(BlockExport *blk_exp)
if (exp->fd_handler_set_up) {
aio_set_fd_handler(exp->common.ctx,
fuse_session_fd(exp->fuse_session), true,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
exp->fd_handler_set_up = false;
}
}

19
block/io_uring.c
View File

@ -292,12 +292,14 @@ static bool qemu_luring_poll_cb(void *opaque)
{
LuringState *s = opaque;
if (io_uring_cq_ready(&s->ring)) {
luring_process_completions_and_submit(s);
return true;
}
return io_uring_cq_ready(&s->ring);
}
return false;
static void qemu_luring_poll_ready(void *opaque)
{
LuringState *s = opaque;
luring_process_completions_and_submit(s);
}
static void ioq_init(LuringQueue *io_q)
@ -402,8 +404,8 @@ int coroutine_fn luring_co_submit(BlockDriverState *bs, LuringState *s, int fd,
void luring_detach_aio_context(LuringState *s, AioContext *old_context)
{
aio_set_fd_handler(old_context, s->ring.ring_fd, false, NULL, NULL, NULL,
s);
aio_set_fd_handler(old_context, s->ring.ring_fd, false,
NULL, NULL, NULL, NULL, s);
qemu_bh_delete(s->completion_bh);
s->aio_context = NULL;
}
@ -413,7 +415,8 @@ void luring_attach_aio_context(LuringState *s, AioContext *new_context)
s->aio_context = new_context;
s->completion_bh = aio_bh_new(new_context, qemu_luring_completion_bh, s);
aio_set_fd_handler(s->aio_context, s->ring.ring_fd, false,
qemu_luring_completion_cb, NULL, qemu_luring_poll_cb, s);
qemu_luring_completion_cb, NULL,
qemu_luring_poll_cb, qemu_luring_poll_ready, s);
}
LuringState *luring_init(Error **errp)

4
block/iscsi.c
View File

@ -363,7 +363,7 @@ iscsi_set_events(IscsiLun *iscsilun)
false,
(ev & POLLIN) ? iscsi_process_read : NULL,
(ev & POLLOUT) ? iscsi_process_write : NULL,
NULL,
NULL, NULL,
iscsilun);
iscsilun->events = ev;
}
@ -1534,7 +1534,7 @@ static void iscsi_detach_aio_context(BlockDriverState *bs)
IscsiLun *iscsilun = bs->opaque;
aio_set_fd_handler(iscsilun->aio_context, iscsi_get_fd(iscsilun->iscsi),
false, NULL, NULL, NULL, NULL);
false, NULL, NULL, NULL, NULL, NULL);
iscsilun->events = 0;
if (iscsilun->nop_timer) {

16
block/linux-aio.c
View File

@ -263,12 +263,15 @@ static bool qemu_laio_poll_cb(void *opaque)
LinuxAioState *s = container_of(e, LinuxAioState, e);
struct io_event *events;
if (!io_getevents_peek(s->ctx, &events)) {
return false;
}
return io_getevents_peek(s->ctx, &events);
}
static void qemu_laio_poll_ready(EventNotifier *opaque)
{
EventNotifier *e = opaque;
LinuxAioState *s = container_of(e, LinuxAioState, e);
qemu_laio_process_completions_and_submit(s);
return true;
}
static void ioq_init(LaioQueue *io_q)
@ -427,7 +430,7 @@ int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context)
{
aio_set_event_notifier(old_context, &s->e, false, NULL, NULL);
aio_set_event_notifier(old_context, &s->e, false, NULL, NULL, NULL);
qemu_bh_delete(s->completion_bh);
s->aio_context = NULL;
}
@ -438,7 +441,8 @@ void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context)
s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
aio_set_event_notifier(new_context, &s->e, false,
qemu_laio_completion_cb,
qemu_laio_poll_cb);
qemu_laio_poll_cb,
qemu_laio_poll_ready);
}
LinuxAioState *laio_init(Error **errp)

6
block/nfs.c
View File

@ -197,7 +197,7 @@ static void nfs_set_events(NFSClient *client)
false,
(ev & POLLIN) ? nfs_process_read : NULL,
(ev & POLLOUT) ? nfs_process_write : NULL,
NULL, client);
NULL, NULL, client);
}
client->events = ev;
@ -372,7 +372,7 @@ static void nfs_detach_aio_context(BlockDriverState *bs)
NFSClient *client = bs->opaque;
aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
false, NULL, NULL, NULL, NULL);
false, NULL, NULL, NULL, NULL, NULL);
client->events = 0;
}
@ -390,7 +390,7 @@ static void nfs_client_close(NFSClient *client)
if (client->context) {
qemu_mutex_lock(&client->mutex);
aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
false, NULL, NULL, NULL, NULL);
false, NULL, NULL, NULL, NULL, NULL);
qemu_mutex_unlock(&client->mutex);
if (client->fh) {
nfs_close(client->context, client->fh);

51
block/nvme.c
View File

@ -605,10 +605,8 @@ out:
return ret;
}
static bool nvme_poll_queue(NVMeQueuePair *q)
static void nvme_poll_queue(NVMeQueuePair *q)
{
bool progress = false;
const size_t cqe_offset = q->cq.head * NVME_CQ_ENTRY_BYTES;
NvmeCqe *cqe = (NvmeCqe *)&q->cq.queue[cqe_offset];
@ -619,30 +617,23 @@ static bool nvme_poll_queue(NVMeQueuePair *q)
* cannot race with itself.
*/
if ((le16_to_cpu(cqe->status) & 0x1) == q->cq_phase) {
return false;
return;
}
qemu_mutex_lock(&q->lock);
while (nvme_process_completion(q)) {
/* Keep polling */
progress = true;
}
qemu_mutex_unlock(&q->lock);
return progress;
}
static bool nvme_poll_queues(BDRVNVMeState *s)
static void nvme_poll_queues(BDRVNVMeState *s)
{
bool progress = false;
int i;
for (i = 0; i < s->queue_count; i++) {
if (nvme_poll_queue(s->queues[i])) {
progress = true;
}
nvme_poll_queue(s->queues[i]);
}
return progress;
}
static void nvme_handle_event(EventNotifier *n)
@ -703,8 +694,30 @@ static bool nvme_poll_cb(void *opaque)
EventNotifier *e = opaque;
BDRVNVMeState *s = container_of(e, BDRVNVMeState,
irq_notifier[MSIX_SHARED_IRQ_IDX]);
int i;
return nvme_poll_queues(s);
for (i = 0; i < s->queue_count; i++) {
NVMeQueuePair *q = s->queues[i];
const size_t cqe_offset = q->cq.head * NVME_CQ_ENTRY_BYTES;
NvmeCqe *cqe = (NvmeCqe *)&q->cq.queue[cqe_offset];
/*
* q->lock isn't needed because nvme_process_completion() only runs in
* the event loop thread and cannot race with itself.
*/
if ((le16_to_cpu(cqe->status) & 0x1) != q->cq_phase) {
return true;
}
}
return false;
}
static void nvme_poll_ready(EventNotifier *e)
{
BDRVNVMeState *s = container_of(e, BDRVNVMeState,
irq_notifier[MSIX_SHARED_IRQ_IDX]);
nvme_poll_queues(s);
}
static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
@ -839,7 +852,8 @@ static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
}
aio_set_event_notifier(bdrv_get_aio_context(bs),
&s->irq_notifier[MSIX_SHARED_IRQ_IDX],
false, nvme_handle_event, nvme_poll_cb);
false, nvme_handle_event, nvme_poll_cb,
nvme_poll_ready);
if (!nvme_identify(bs, namespace, errp)) {
ret = -EIO;
@ -924,7 +938,7 @@ static void nvme_close(BlockDriverState *bs)
g_free(s->queues);
aio_set_event_notifier(bdrv_get_aio_context(bs),
&s->irq_notifier[MSIX_SHARED_IRQ_IDX],
false, NULL, NULL);
false, NULL, NULL, NULL);
event_notifier_cleanup(&s->irq_notifier[MSIX_SHARED_IRQ_IDX]);
qemu_vfio_pci_unmap_bar(s->vfio, 0, s->bar0_wo_map,
0, sizeof(NvmeBar) + NVME_DOORBELL_SIZE);
@ -1520,7 +1534,7 @@ static void nvme_detach_aio_context(BlockDriverState *bs)
aio_set_event_notifier(bdrv_get_aio_context(bs),
&s->irq_notifier[MSIX_SHARED_IRQ_IDX],
false, NULL, NULL);
false, NULL, NULL, NULL);
}
static void nvme_attach_aio_context(BlockDriverState *bs,
@ -1530,7 +1544,8 @@ static void nvme_attach_aio_context(BlockDriverState *bs,
s->aio_context = new_context;
aio_set_event_notifier(new_context, &s->irq_notifier[MSIX_SHARED_IRQ_IDX],
false, nvme_handle_event, nvme_poll_cb);
false, nvme_handle_event, nvme_poll_cb,
nvme_poll_ready);
for (unsigned i = 0; i < s->queue_count; i++) {
NVMeQueuePair *q = s->queues[i];

4
block/ssh.c
View File

@ -990,7 +990,7 @@ static void restart_coroutine(void *opaque)
AioContext *ctx = bdrv_get_aio_context(bs);
trace_ssh_restart_coroutine(restart->co);
aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL);
aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL, NULL);
aio_co_wake(restart->co);
}
@ -1020,7 +1020,7 @@ static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
trace_ssh_co_yield(s->sock, rd_handler, wr_handler);
aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
false, rd_handler, wr_handler, NULL, &restart);
false, rd_handler, wr_handler, NULL, NULL, &restart);
qemu_coroutine_yield();
trace_ssh_co_yield_back(s->sock);
}

4
block/win32-aio.c
View File

@ -172,7 +172,7 @@ int win32_aio_attach(QEMUWin32AIOState *aio, HANDLE hfile)
void win32_aio_detach_aio_context(QEMUWin32AIOState *aio,
AioContext *old_context)
{
aio_set_event_notifier(old_context, &aio->e, false, NULL, NULL);
aio_set_event_notifier(old_context, &aio->e, false, NULL, NULL, NULL);
aio->aio_ctx = NULL;
}
@ -181,7 +181,7 @@ void win32_aio_attach_aio_context(QEMUWin32AIOState *aio,
{
aio->aio_ctx = new_context;
aio_set_event_notifier(new_context, &aio->e, false,
win32_aio_completion_cb, NULL);
win32_aio_completion_cb, NULL, NULL);
}
QEMUWin32AIOState *win32_aio_init(void)

16
hw/virtio/virtio.c
View File

@ -3536,11 +3536,14 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque)
EventNotifier *n = opaque;
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
if (!vq->vring.desc || virtio_queue_empty(vq)) {
return false;
}
return vq->vring.desc && !virtio_queue_empty(vq);
}
return virtio_queue_notify_aio_vq(vq);
static void virtio_queue_host_notifier_aio_poll_ready(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
virtio_queue_notify_aio_vq(vq);
}
static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n)
@ -3558,12 +3561,13 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
vq->handle_aio_output = handle_output;
aio_set_event_notifier(ctx, &vq->host_notifier, true,
virtio_queue_host_notifier_aio_read,
virtio_queue_host_notifier_aio_poll);
virtio_queue_host_notifier_aio_poll,
virtio_queue_host_notifier_aio_poll_ready);
aio_set_event_notifier_poll(ctx, &vq->host_notifier,
virtio_queue_host_notifier_aio_poll_begin,
virtio_queue_host_notifier_aio_poll_end);
} else {
aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL, NULL);
aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL, NULL, NULL);
/* Test and clear notifier before after disabling event,
* in case poll callback didn't have time to run. */
virtio_queue_host_notifier_aio_read(&vq->host_notifier);

6
hw/xen/xen-bus.c
View File

@ -1115,11 +1115,11 @@ void xen_device_set_event_channel_context(XenDevice *xendev,
if (channel->ctx)
aio_set_fd_handler(channel->ctx, xenevtchn_fd(channel->xeh), true,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
channel->ctx = ctx;
aio_set_fd_handler(channel->ctx, xenevtchn_fd(channel->xeh), true,
xen_device_event, NULL, xen_device_poll, channel);
xen_device_event, NULL, xen_device_poll, NULL, channel);
}
XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
@ -1193,7 +1193,7 @@ void xen_device_unbind_event_channel(XenDevice *xendev,
QLIST_REMOVE(channel, list);
aio_set_fd_handler(channel->ctx, xenevtchn_fd(channel->xeh), true,
NULL, NULL, NULL, NULL);
NULL, NULL, NULL, NULL, NULL);
if (xenevtchn_unbind(channel->xeh, channel->local_port) < 0) {
error_setg_errno(errp, errno, "xenevtchn_unbind failed");

4
include/block/aio.h
View File

@ -469,6 +469,7 @@ void aio_set_fd_handler(AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
AioPollFn *io_poll,
IOHandler *io_poll_ready,
void *opaque);
/* Set polling begin/end callbacks for a file descriptor that has already been
@ -490,7 +491,8 @@ void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
bool is_external,
EventNotifierHandler *io_read,
AioPollFn *io_poll);
AioPollFn *io_poll,
EventNotifierHandler *io_poll_ready);
/* Set polling begin/end callbacks for an event notifier that has already been
* registered with aio_set_event_notifier. Do nothing if the event notifier is

6
io/channel-command.c
View File

@ -346,8 +346,10 @@ static void qio_channel_command_set_aio_fd_handler(QIOChannel *ioc,
void *opaque)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
aio_set_fd_handler(ctx, cioc->readfd, false, io_read, NULL, NULL, opaque);
aio_set_fd_handler(ctx, cioc->writefd, false, NULL, io_write, NULL, opaque);
aio_set_fd_handler(ctx, cioc->readfd, false,
io_read, NULL, NULL, NULL, opaque);
aio_set_fd_handler(ctx, cioc->writefd, false,
NULL, io_write, NULL, NULL, opaque);
}

3
io/channel-file.c
View File

@ -191,7 +191,8 @@ static void qio_channel_file_set_aio_fd_handler(QIOChannel *ioc,
void *opaque)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
aio_set_fd_handler(ctx, fioc->fd, false, io_read, io_write, NULL, opaque);
aio_set_fd_handler(ctx, fioc->fd, false, io_read, io_write,
NULL, NULL, opaque);
}
static GSource *qio_channel_file_create_watch(QIOChannel *ioc,

3
io/channel-socket.c
View File

@ -761,7 +761,8 @@ static void qio_channel_socket_set_aio_fd_handler(QIOChannel *ioc,
void *opaque)
{
QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
aio_set_fd_handler(ctx, sioc->fd, false, io_read, io_write, NULL, opaque);
aio_set_fd_handler(ctx, sioc->fd, false,
io_read, io_write, NULL, NULL, opaque);
}
static GSource *qio_channel_socket_create_watch(QIOChannel *ioc,

8
migration/rdma.c
View File

@ -3161,14 +3161,14 @@ static void qio_channel_rdma_set_aio_fd_handler(QIOChannel *ioc,
QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
if (io_read) {
aio_set_fd_handler(ctx, rioc->rdmain->recv_comp_channel->fd,
false, io_read, io_write, NULL, opaque);
false, io_read, io_write, NULL, NULL, opaque);
aio_set_fd_handler(ctx, rioc->rdmain->send_comp_channel->fd,
false, io_read, io_write, NULL, opaque);
false, io_read, io_write, NULL, NULL, opaque);
} else {
aio_set_fd_handler(ctx, rioc->rdmaout->recv_comp_channel->fd,
false, io_read, io_write, NULL, opaque);
false, io_read, io_write, NULL, NULL, opaque);
aio_set_fd_handler(ctx, rioc->rdmaout->send_comp_channel->fd,
false, io_read, io_write, NULL, opaque);
false, io_read, io_write, NULL, NULL, opaque);
}
}

4
tests/unit/test-aio.c
View File

@ -130,7 +130,7 @@ static void *test_acquire_thread(void *opaque)
static void set_event_notifier(AioContext *ctx, EventNotifier *notifier,
EventNotifierHandler *handler)
{
aio_set_event_notifier(ctx, notifier, false, handler, NULL);
aio_set_event_notifier(ctx, notifier, false, handler, NULL, NULL);
}
static void dummy_notifier_read(EventNotifier *n)
@ -390,7 +390,7 @@ static void test_aio_external_client(void)
for (i = 1; i < 3; i++) {
EventNotifierTestData data = { .n = 0, .active = 10, .auto_set = true };
event_notifier_init(&data.e, false);
aio_set_event_notifier(ctx, &data.e, true, event_ready_cb, NULL);
aio_set_event_notifier(ctx, &data.e, true, event_ready_cb, NULL, NULL);
event_notifier_set(&data.e);
for (j = 0; j < i; j++) {
aio_disable_external(ctx);

4
tests/unit/test-fdmon-epoll.c
View File

@ -22,14 +22,14 @@ static void add_event_notifiers(EventNotifier *notifiers, size_t n)
for (size_t i = 0; i < n; i++) {
event_notifier_init(&notifiers[i], false);
aio_set_event_notifier(ctx, &notifiers[i], false,
dummy_fd_handler, NULL);
dummy_fd_handler, NULL, NULL);
}
}
static void remove_event_notifiers(EventNotifier *notifiers, size_t n)
{
for (size_t i = 0; i < n; i++) {
aio_set_event_notifier(ctx, &notifiers[i], false, NULL, NULL);
aio_set_event_notifier(ctx, &notifiers[i], false, NULL, NULL, NULL);
event_notifier_cleanup(&notifiers[i]);
}
}

89
util/aio-posix.c
View File

@ -23,6 +23,15 @@
#include "trace.h"
#include "aio-posix.h"
/*
* G_IO_IN and G_IO_OUT are not appropriate revents values for polling, since
* the handler may not need to access the file descriptor. For example, the
* handler doesn't need to read from an EventNotifier if it polled a memory
* location and a read syscall would be slow. Define our own unique revents
* value to indicate that polling determined this AioHandler is ready.
*/
#define REVENTS_POLL_READY 0
/* Stop userspace polling on a handler if it isn't active for some time */
#define POLL_IDLE_INTERVAL_NS (7 * NANOSECONDS_PER_SECOND)
@ -93,6 +102,7 @@ void aio_set_fd_handler(AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
AioPollFn *io_poll,
IOHandler *io_poll_ready,
void *opaque)
{
AioHandler *node;
@ -101,6 +111,10 @@ void aio_set_fd_handler(AioContext *ctx,
bool deleted = false;
int poll_disable_change;
if (io_poll && !io_poll_ready) {
io_poll = NULL; /* polling only makes sense if there is a handler */
}
qemu_lockcnt_lock(&ctx->list_lock);
node = find_aio_handler(ctx, fd);
@ -127,6 +141,7 @@ void aio_set_fd_handler(AioContext *ctx,
new_node->io_read = io_read;
new_node->io_write = io_write;
new_node->io_poll = io_poll;
new_node->io_poll_ready = io_poll_ready;
new_node->opaque = opaque;
new_node->is_external = is_external;
@ -182,10 +197,12 @@ void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
bool is_external,
EventNotifierHandler *io_read,
AioPollFn *io_poll)
AioPollFn *io_poll,
EventNotifierHandler *io_poll_ready)
{
aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), is_external,
(IOHandler *)io_read, NULL, io_poll, notifier);
(IOHandler *)io_read, NULL, io_poll,
(IOHandler *)io_poll_ready, notifier);
}
void aio_set_event_notifier_poll(AioContext *ctx,
@ -198,7 +215,8 @@ void aio_set_event_notifier_poll(AioContext *ctx,
(IOHandler *)io_poll_end);
}
static bool poll_set_started(AioContext *ctx, bool started)
static bool poll_set_started(AioContext *ctx, AioHandlerList *ready_list,
bool started)
{
AioHandler *node;
bool progress = false;
@ -228,8 +246,9 @@ static bool poll_set_started(AioContext *ctx, bool started)
}
/* Poll one last time in case ->io_poll_end() raced with the event */
if (!started) {
progress = node->io_poll(node->opaque) || progress;
if (!started && node->io_poll(node->opaque)) {
aio_add_ready_handler(ready_list, node, REVENTS_POLL_READY);
progress = true;
}
}
qemu_lockcnt_dec(&ctx->list_lock);
@ -240,8 +259,11 @@ static bool poll_set_started(AioContext *ctx, bool started)
bool aio_prepare(AioContext *ctx)
{
AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list);
/* Poll mode cannot be used with glib's event loop, disable it. */
poll_set_started(ctx, false);
poll_set_started(ctx, &ready_list, false);
/* TODO what to do with this list? */
return false;
}
@ -321,6 +343,18 @@ static bool aio_dispatch_handler(AioContext *ctx, AioHandler *node)
}
QLIST_INSERT_HEAD(&ctx->poll_aio_handlers, node, node_poll);
}
if (!QLIST_IS_INSERTED(node, node_deleted) &&
revents == 0 &&
aio_node_check(ctx, node->is_external) &&
node->io_poll_ready) {
node->io_poll_ready(node->opaque);
/*
* Return early since revents was zero. aio_notify() does not count as
* progress.
*/
return node->opaque != &ctx->notifier;
}
if (!QLIST_IS_INSERTED(node, node_deleted) &&
(revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
@ -387,6 +421,7 @@ void aio_dispatch(AioContext *ctx)
}
static bool run_poll_handlers_once(AioContext *ctx,
AioHandlerList *ready_list,
int64_t now,
int64_t *timeout)
{
@ -397,6 +432,8 @@ static bool run_poll_handlers_once(AioContext *ctx,
QLIST_FOREACH_SAFE(node, &ctx->poll_aio_handlers, node_poll, tmp) {
if (aio_node_check(ctx, node->is_external) &&
node->io_poll(node->opaque)) {
aio_add_ready_handler(ready_list, node, REVENTS_POLL_READY);
node->poll_idle_timeout = now + POLL_IDLE_INTERVAL_NS;
/*
@ -420,7 +457,9 @@ static bool fdmon_supports_polling(AioContext *ctx)
return ctx->fdmon_ops->need_wait != aio_poll_disabled;
}
static bool remove_idle_poll_handlers(AioContext *ctx, int64_t now)
static bool remove_idle_poll_handlers(AioContext *ctx,
AioHandlerList *ready_list,
int64_t now)
{
AioHandler *node;
AioHandler *tmp;
@ -451,7 +490,11 @@ static bool remove_idle_poll_handlers(AioContext *ctx, int64_t now)
* Nevermind about re-adding the handler in the rare case where
* this causes progress.
*/
progress = node->io_poll(node->opaque) || progress;
if (node->io_poll(node->opaque)) {
aio_add_ready_handler(ready_list, node,
REVENTS_POLL_READY);
progress = true;
}
}
}
}
@ -461,6 +504,7 @@ static bool remove_idle_poll_handlers(AioContext *ctx, int64_t now)
/* run_poll_handlers:
* @ctx: the AioContext
* @ready_list: the list to place ready handlers on
* @max_ns: maximum time to poll for, in nanoseconds
*
* Polls for a given time.
@ -469,7 +513,8 @@ static bool remove_idle_poll_handlers(AioContext *ctx, int64_t now)
*
* Returns: true if progress was made, false otherwise
*/
static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
static bool run_poll_handlers(AioContext *ctx, AioHandlerList *ready_list,
int64_t max_ns, int64_t *timeout)
{
bool progress;
int64_t start_time, elapsed_time;
@ -490,13 +535,15 @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
start_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
do {
progress = run_poll_handlers_once(ctx, start_time, timeout);
progress = run_poll_handlers_once(ctx, ready_list,
start_time, timeout);
elapsed_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start_time;
max_ns = qemu_soonest_timeout(*timeout, max_ns);
assert(!(max_ns && progress));
} while (elapsed_time < max_ns && !ctx->fdmon_ops->need_wait(ctx));
if (remove_idle_poll_handlers(ctx, start_time + elapsed_time)) {
if (remove_idle_poll_handlers(ctx, ready_list,
start_time + elapsed_time)) {
*timeout = 0;
progress = true;
}
@ -514,6 +561,7 @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
/* try_poll_mode:
* @ctx: the AioContext
* @ready_list: list to add handlers that need to be run
* @timeout: timeout for blocking wait, computed by the caller and updated if
* polling succeeds.
*
@ -521,7 +569,8 @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
*
* Returns: true if progress was made, false otherwise
*/
static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
int64_t *timeout)
{
int64_t max_ns;
@ -531,14 +580,14 @@ static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
poll_set_started(ctx, true);
poll_set_started(ctx, ready_list, true);
if (run_poll_handlers(ctx, max_ns, timeout)) {
if (run_poll_handlers(ctx, ready_list, max_ns, timeout)) {
return true;
}
}
if (poll_set_started(ctx, false)) {
if (poll_set_started(ctx, ready_list, false)) {
*timeout = 0;
return true;
}
@ -549,7 +598,6 @@ static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
bool aio_poll(AioContext *ctx, bool blocking)
{
AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list);
int ret = 0;
bool progress;
bool use_notify_me;
int64_t timeout;
@ -574,7 +622,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
timeout = blocking ? aio_compute_timeout(ctx) : 0;
progress = try_poll_mode(ctx, &timeout);
progress = try_poll_mode(ctx, &ready_list, &timeout);
assert(!(timeout && progress));
/*
@ -604,7 +652,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
* system call---a single round of run_poll_handlers_once suffices.
*/
if (timeout || ctx->fdmon_ops->need_wait(ctx)) {
ret = ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
}
if (use_notify_me) {
@ -657,10 +705,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
progress |= aio_bh_poll(ctx);
if (ret > 0) {
progress |= aio_dispatch_ready_handlers(ctx, &ready_list);
}
progress |= aio_dispatch_ready_handlers(ctx, &ready_list);
aio_free_deleted_handlers(ctx);

1
util/aio-posix.h
View File

@ -24,6 +24,7 @@ struct AioHandler {
IOHandler *io_read;
IOHandler *io_write;
AioPollFn *io_poll;
IOHandler *io_poll_ready;
IOHandler *io_poll_begin;
IOHandler *io_poll_end;
void *opaque;

4
util/aio-win32.c
View File

@ -68,6 +68,7 @@ void aio_set_fd_handler(AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
AioPollFn *io_poll,
IOHandler *io_poll_ready,
void *opaque)
{
/* fd is a SOCKET in our case */
@ -136,7 +137,8 @@ void aio_set_event_notifier(AioContext *ctx,
EventNotifier *e,
bool is_external,
EventNotifierHandler *io_notify,
AioPollFn *io_poll)
AioPollFn *io_poll,
EventNotifierHandler *io_poll_ready)
{
AioHandler *node;

10
util/async.c
View File

@ -362,7 +362,7 @@ aio_ctx_finalize(GSource *source)
g_free(bh);
}
aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL);
aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL, NULL);
event_notifier_cleanup(&ctx->notifier);
qemu_rec_mutex_destroy(&ctx->lock);
qemu_lockcnt_destroy(&ctx->list_lock);
@ -485,6 +485,11 @@ static bool aio_context_notifier_poll(void *opaque)
return qatomic_read(&ctx->notified);
}
static void aio_context_notifier_poll_ready(EventNotifier *e)
{
/* Do nothing, we just wanted to kick the event loop */
}
static void co_schedule_bh_cb(void *opaque)
{
AioContext *ctx = opaque;
@ -536,7 +541,8 @@ AioContext *aio_context_new(Error **errp)
aio_set_event_notifier(ctx, &ctx->notifier,
false,
aio_context_notifier_cb,
aio_context_notifier_poll);
aio_context_notifier_poll,
aio_context_notifier_poll_ready);
#ifdef CONFIG_LINUX_AIO
ctx->linux_aio = NULL;
#endif

4
util/main-loop.c
View File

@ -582,7 +582,7 @@ void qemu_set_fd_handler(int fd,
{
iohandler_init();
aio_set_fd_handler(iohandler_ctx, fd, false,
fd_read, fd_write, NULL, opaque);
fd_read, fd_write, NULL, NULL, opaque);
}
void event_notifier_set_handler(EventNotifier *e,
@ -590,5 +590,5 @@ void event_notifier_set_handler(EventNotifier *e,
{
iohandler_init();
aio_set_event_notifier(iohandler_ctx, e, false,
handler, NULL);
handler, NULL, NULL);
}

5
util/qemu-coroutine-io.c
View File

@ -75,7 +75,8 @@ typedef struct {
static void fd_coroutine_enter(void *opaque)
{
FDYieldUntilData *data = opaque;
aio_set_fd_handler(data->ctx, data->fd, false, NULL, NULL, NULL, NULL);
aio_set_fd_handler(data->ctx, data->fd, false,
NULL, NULL, NULL, NULL, NULL);
qemu_coroutine_enter(data->co);
}
@ -88,6 +89,6 @@ void coroutine_fn yield_until_fd_readable(int fd)
data.co = qemu_coroutine_self();
data.fd = fd;
aio_set_fd_handler(
data.ctx, fd, false, fd_coroutine_enter, NULL, NULL, &data);
data.ctx, fd, false, fd_coroutine_enter, NULL, NULL, NULL, &data);
qemu_coroutine_yield();
}

11
util/vhost-user-server.c
View File

@ -250,7 +250,7 @@ set_watch(VuDev *vu_dev, int fd, int vu_evt,
vu_fd_watch->cb = cb;
qemu_set_nonblock(fd);
aio_set_fd_handler(server->ioc->ctx, fd, true, kick_handler,
NULL, NULL, vu_fd_watch);
NULL, NULL, NULL, vu_fd_watch);
vu_fd_watch->vu_dev = vu_dev;
vu_fd_watch->pvt = pvt;
}
@ -270,7 +270,8 @@ static void remove_watch(VuDev *vu_dev, int fd)
if (!vu_fd_watch) {
return;
}
aio_set_fd_handler(server->ioc->ctx, fd, true, NULL, NULL, NULL, NULL);
aio_set_fd_handler(server->ioc->ctx, fd, true,
NULL, NULL, NULL, NULL, NULL);
QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
g_free(vu_fd_watch);
@ -334,7 +335,7 @@ void vhost_user_server_stop(VuServer *server)
QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
NULL, NULL, NULL, vu_fd_watch);
NULL, NULL, NULL, NULL, vu_fd_watch);
}
qio_channel_shutdown(server->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
@ -377,7 +378,7 @@ void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx)
QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
aio_set_fd_handler(ctx, vu_fd_watch->fd, true, kick_handler, NULL,
NULL, vu_fd_watch);
NULL, NULL, vu_fd_watch);
}
aio_co_schedule(ctx, server->co_trip);
@ -391,7 +392,7 @@ void vhost_user_server_detach_aio_context(VuServer *server)
QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
NULL, NULL, NULL, vu_fd_watch);
NULL, NULL, NULL, NULL, vu_fd_watch);
}
qio_channel_detach_aio_context(server->ioc);