84005f4a2b
The kernel allocates extra metadata SKBs in case of a zerocopy send,
eventually used for zerocopy's notification mechanism. This metadata
memory is accounted for in the OPTMEM limit. The kernel queues
completion notifications on the socket error queue and this error queue
is freed when userspace reads it.
Usually, in the case of in-order processing, the kernel will batch the
notifications and merge the metadata into a single SKB and free the
rest. As a result, it never exceeds the OPTMEM limit. However, if there
is any out-of-order processing or intermittent zerocopy failures, this
error chain can grow significantly, exhausting the OPTMEM limit. As a
result, all new sendmsg requests fail to allocate any new SKB, leading
to an ENOBUF error. Depending on the amount of data queued before the
flush (i.e., large live migration iterations), even large OPTMEM limits
are prone to failure.
To work around this, if we encounter an ENOBUF error with a zerocopy
sendmsg, flush the error queue and retry once more.
Co-authored-by: Manish Mishra <manish.mishra@nutanix.com>
Signed-off-by: Tejus GK <tejus.gk@nutanix.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[DB: change TRUE/FALSE to true/false for 'bool' type;
add more #ifdef QEMU_MSG_ZEROCOPY blocks]
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
284 lines
9.7 KiB
C
284 lines
9.7 KiB
C
/*
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* QEMU I/O channels sockets driver
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*
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* Copyright (c) 2015 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef QIO_CHANNEL_SOCKET_H
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#define QIO_CHANNEL_SOCKET_H
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#include "io/channel.h"
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#include "io/task.h"
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#include "qemu/sockets.h"
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#include "qom/object.h"
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#define TYPE_QIO_CHANNEL_SOCKET "qio-channel-socket"
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OBJECT_DECLARE_SIMPLE_TYPE(QIOChannelSocket, QIO_CHANNEL_SOCKET)
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/**
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* QIOChannelSocket:
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*
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* The QIOChannelSocket class provides a channel implementation
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* that can transport data over a UNIX socket or TCP socket.
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* Beyond the core channel API, it also provides functionality
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* for accepting client connections, tuning some socket
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* parameters and getting socket address strings.
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*/
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struct QIOChannelSocket {
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QIOChannel parent;
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int fd;
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struct sockaddr_storage localAddr;
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socklen_t localAddrLen;
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struct sockaddr_storage remoteAddr;
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socklen_t remoteAddrLen;
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ssize_t zero_copy_queued;
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ssize_t zero_copy_sent;
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bool blocking;
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/**
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* This flag indicates whether any new data was successfully sent with
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* zerocopy since the last qio_channel_socket_flush() call.
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*/
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bool new_zero_copy_sent_success;
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};
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/**
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* qio_channel_socket_new:
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*
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* Create a channel for performing I/O on a socket
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* connection, that is initially closed. After
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* creating the socket, it must be setup as a client
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* connection or server.
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*
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* Returns: the socket channel object
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*/
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QIOChannelSocket *
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qio_channel_socket_new(void);
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/**
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* qio_channel_socket_new_fd:
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* @fd: the socket file descriptor
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a channel for performing I/O on the socket
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* connection represented by the file descriptor @fd.
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*
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* Returns: the socket channel object, or NULL on error
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*/
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QIOChannelSocket *
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qio_channel_socket_new_fd(int fd,
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Error **errp);
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/**
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* qio_channel_socket_connect_sync:
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* @ioc: the socket channel object
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* @addr: the address to connect to
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* @errp: pointer to a NULL-initialized error object
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*
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* Attempt to connect to the address @addr. This method
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* will run in the foreground so the caller will not regain
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* execution control until the connection is established or
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* an error occurs.
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*/
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int qio_channel_socket_connect_sync(QIOChannelSocket *ioc,
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SocketAddress *addr,
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Error **errp);
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/**
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* qio_channel_socket_connect_async:
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* @ioc: the socket channel object
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* @addr: the address to connect to
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* @callback: the function to invoke on completion
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* @opaque: user data to pass to @callback
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* @destroy: the function to free @opaque
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* @context: the context to run the async task. If %NULL, the default
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* context will be used.
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*
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* Attempt to connect to the address @addr. This method
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* will run in the background so the caller will regain
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* execution control immediately. The function @callback
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* will be invoked on completion or failure. The @addr
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* parameter will be copied, so may be freed as soon
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* as this function returns without waiting for completion.
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*/
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void qio_channel_socket_connect_async(QIOChannelSocket *ioc,
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SocketAddress *addr,
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QIOTaskFunc callback,
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gpointer opaque,
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GDestroyNotify destroy,
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GMainContext *context);
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/**
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* qio_channel_socket_listen_sync:
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* @ioc: the socket channel object
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* @addr: the address to listen to
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* @num: the expected amount of connections
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* @errp: pointer to a NULL-initialized error object
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*
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* Attempt to listen to the address @addr. This method
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* will run in the foreground so the caller will not regain
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* execution control until the connection is established or
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* an error occurs.
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*/
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int qio_channel_socket_listen_sync(QIOChannelSocket *ioc,
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SocketAddress *addr,
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int num,
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Error **errp);
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/**
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* qio_channel_socket_listen_async:
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* @ioc: the socket channel object
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* @addr: the address to listen to
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* @num: the expected amount of connections
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* @callback: the function to invoke on completion
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* @opaque: user data to pass to @callback
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* @destroy: the function to free @opaque
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* @context: the context to run the async task. If %NULL, the default
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* context will be used.
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*
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* Attempt to listen to the address @addr. This method
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* will run in the background so the caller will regain
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* execution control immediately. The function @callback
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* will be invoked on completion or failure. The @addr
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* parameter will be copied, so may be freed as soon
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* as this function returns without waiting for completion.
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*/
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void qio_channel_socket_listen_async(QIOChannelSocket *ioc,
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SocketAddress *addr,
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int num,
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QIOTaskFunc callback,
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gpointer opaque,
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GDestroyNotify destroy,
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GMainContext *context);
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/**
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* qio_channel_socket_dgram_sync:
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* @ioc: the socket channel object
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* @localAddr: the address to local bind address
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* @remoteAddr: the address to remote peer address
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* @errp: pointer to a NULL-initialized error object
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*
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* Attempt to initialize a datagram socket bound to
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* @localAddr and communicating with peer @remoteAddr.
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* This method will run in the foreground so the caller
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* will not regain execution control until the socket
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* is established or an error occurs.
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*/
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int qio_channel_socket_dgram_sync(QIOChannelSocket *ioc,
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SocketAddress *localAddr,
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SocketAddress *remoteAddr,
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Error **errp);
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/**
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* qio_channel_socket_dgram_async:
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* @ioc: the socket channel object
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* @localAddr: the address to local bind address
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* @remoteAddr: the address to remote peer address
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* @callback: the function to invoke on completion
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* @opaque: user data to pass to @callback
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* @destroy: the function to free @opaque
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* @context: the context to run the async task. If %NULL, the default
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* context will be used.
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*
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* Attempt to initialize a datagram socket bound to
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* @localAddr and communicating with peer @remoteAddr.
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* This method will run in the background so the caller
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* will regain execution control immediately. The function
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* @callback will be invoked on completion or failure.
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* The @localAddr and @remoteAddr parameters will be copied,
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* so may be freed as soon as this function returns without
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* waiting for completion.
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*/
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void qio_channel_socket_dgram_async(QIOChannelSocket *ioc,
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SocketAddress *localAddr,
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SocketAddress *remoteAddr,
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QIOTaskFunc callback,
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gpointer opaque,
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GDestroyNotify destroy,
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GMainContext *context);
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/**
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* qio_channel_socket_get_local_address:
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* @ioc: the socket channel object
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* @errp: pointer to a NULL-initialized error object
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*
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* Get the string representation of the local socket
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* address. A pointer to the allocated address information
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* struct will be returned, which the caller is required to
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* release with a call qapi_free_SocketAddress() when no
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* longer required.
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*
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* Returns: 0 on success, -1 on error
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*/
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SocketAddress *
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qio_channel_socket_get_local_address(QIOChannelSocket *ioc,
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Error **errp);
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/**
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* qio_channel_socket_get_remote_address:
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* @ioc: the socket channel object
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* @errp: pointer to a NULL-initialized error object
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*
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* Get the string representation of the local socket
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* address. A pointer to the allocated address information
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* struct will be returned, which the caller is required to
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* release with a call qapi_free_SocketAddress() when no
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* longer required.
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*
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* Returns: the socket address struct, or NULL on error
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*/
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SocketAddress *
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qio_channel_socket_get_remote_address(QIOChannelSocket *ioc,
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Error **errp);
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/**
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* qio_channel_socket_accept:
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* @ioc: the socket channel object
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* @errp: pointer to a NULL-initialized error object
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*
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* If the socket represents a server, then this accepts
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* a new client connection. The returned channel will
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* represent the connected client socket.
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*
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* Returns: the new client channel, or NULL on error
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*/
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QIOChannelSocket *
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qio_channel_socket_accept(QIOChannelSocket *ioc,
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Error **errp);
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/**
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* qio_channel_socket_set_send_buffer:
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* @ioc: the socket channel object
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* @size: buffer size
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* @errp: pointer to a NULL-initialized error object
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*
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* Set the underlying socket send buffer size.
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*
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* Retruns: 0 on success, or -1 on error.
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*/
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int qio_channel_socket_set_send_buffer(QIOChannelSocket *ioc,
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size_t size,
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Error **errp);
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#endif /* QIO_CHANNEL_SOCKET_H */
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