qemu-e2k/io/channel-file.c

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/*
* QEMU I/O channels files driver
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "io/channel-file.h"
#include "io/channel-watch.h"
2016-03-14 09:01:28 +01:00
#include "qapi/error.h"
#include "qemu/module.h"
#include "qemu/sockets.h"
#include "trace.h"
QIOChannelFile *
qio_channel_file_new_fd(int fd)
{
QIOChannelFile *ioc;
ioc = QIO_CHANNEL_FILE(object_new(TYPE_QIO_CHANNEL_FILE));
ioc->fd = fd;
trace_qio_channel_file_new_fd(ioc, fd);
return ioc;
}
QIOChannelFile *
qio_channel_file_new_path(const char *path,
int flags,
mode_t mode,
Error **errp)
{
QIOChannelFile *ioc;
ioc = QIO_CHANNEL_FILE(object_new(TYPE_QIO_CHANNEL_FILE));
ioc->fd = qemu_open_old(path, flags, mode);
if (ioc->fd < 0) {
object_unref(OBJECT(ioc));
error_setg_errno(errp, errno,
"Unable to open %s", path);
return NULL;
}
trace_qio_channel_file_new_path(ioc, path, flags, mode, ioc->fd);
return ioc;
}
static void qio_channel_file_init(Object *obj)
{
QIOChannelFile *ioc = QIO_CHANNEL_FILE(obj);
ioc->fd = -1;
}
static void qio_channel_file_finalize(Object *obj)
{
QIOChannelFile *ioc = QIO_CHANNEL_FILE(obj);
if (ioc->fd != -1) {
qemu_close(ioc->fd);
ioc->fd = -1;
}
}
static ssize_t qio_channel_file_readv(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int **fds,
size_t *nfds,
int flags,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
ssize_t ret;
retry:
ret = readv(fioc->fd, iov, niov);
if (ret < 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno,
"Unable to read from file");
return -1;
}
return ret;
}
static ssize_t qio_channel_file_writev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int *fds,
size_t nfds,
int flags,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
ssize_t ret;
retry:
ret = writev(fioc->fd, iov, niov);
if (ret <= 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno,
"Unable to write to file");
return -1;
}
return ret;
}
static int qio_channel_file_set_blocking(QIOChannel *ioc,
bool enabled,
Error **errp)
{
#ifdef WIN32
/* not implemented */
error_setg_errno(errp, errno, "Failed to set FD nonblocking");
return -1;
#else
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
if (!g_unix_set_fd_nonblocking(fioc->fd, !enabled, NULL)) {
error_setg_errno(errp, errno, "Failed to set FD nonblocking");
return -1;
}
return 0;
#endif
}
static off_t qio_channel_file_seek(QIOChannel *ioc,
off_t offset,
int whence,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
off_t ret;
ret = lseek(fioc->fd, offset, whence);
if (ret == (off_t)-1) {
error_setg_errno(errp, errno,
"Unable to seek to offset %lld whence %d in file",
(long long int)offset, whence);
return -1;
}
return ret;
}
static int qio_channel_file_close(QIOChannel *ioc,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
if (qemu_close(fioc->fd) < 0) {
error_setg_errno(errp, errno,
"Unable to close file");
return -1;
}
fioc->fd = -1;
return 0;
}
static void qio_channel_file_set_aio_fd_handler(QIOChannel *ioc,
AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
void *opaque)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
aio-posix: split poll check from ready handler 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>
2021-12-07 14:23:31 +01:00
aio_set_fd_handler(ctx, fioc->fd, false, io_read, io_write,
NULL, NULL, opaque);
}
static GSource *qio_channel_file_create_watch(QIOChannel *ioc,
GIOCondition condition)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
return qio_channel_create_fd_watch(ioc,
fioc->fd,
condition);
}
static void qio_channel_file_class_init(ObjectClass *klass,
void *class_data G_GNUC_UNUSED)
{
QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
ioc_klass->io_writev = qio_channel_file_writev;
ioc_klass->io_readv = qio_channel_file_readv;
ioc_klass->io_set_blocking = qio_channel_file_set_blocking;
ioc_klass->io_seek = qio_channel_file_seek;
ioc_klass->io_close = qio_channel_file_close;
ioc_klass->io_create_watch = qio_channel_file_create_watch;
ioc_klass->io_set_aio_fd_handler = qio_channel_file_set_aio_fd_handler;
}
static const TypeInfo qio_channel_file_info = {
.parent = TYPE_QIO_CHANNEL,
.name = TYPE_QIO_CHANNEL_FILE,
.instance_size = sizeof(QIOChannelFile),
.instance_init = qio_channel_file_init,
.instance_finalize = qio_channel_file_finalize,
.class_init = qio_channel_file_class_init,
};
static void qio_channel_file_register_types(void)
{
type_register_static(&qio_channel_file_info);
}
type_init(qio_channel_file_register_types);