From e2e360db7a55afd62e77577a965f6aa224132cef Mon Sep 17 00:00:00 2001 From: Nir Soffer Date: Sat, 17 May 2025 23:11:52 +0300 Subject: [PATCH] io: Add helper for setting socket send buffer size MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Testing reading and writing from qemu-nbd using a unix domain socket shows that the platform default send buffer size is too low, leading to poor performance and hight cpu usage. Add a helper for setting socket send buffer size to be used in NBD code. It can also be used in other contexts. We don't need a helper for receive buffer size since it is not used with unix domain sockets. This is documented for Linux, and not documented for macOS. Failing to set the socket buffer size is not a fatal error, but the caller may want to warn about the failure. Signed-off-by: Nir Soffer Message-ID: <20250517201154.88456-2-nirsof@gmail.com> Reviewed-by: Daniel P. Berrangé Signed-off-by: Eric Blake --- include/io/channel-socket.h | 13 +++++++++++++ io/channel-socket.c | 11 +++++++++++ 2 files changed, 24 insertions(+) diff --git a/include/io/channel-socket.h b/include/io/channel-socket.h index ab15577d38..a88cf8b3a9 100644 --- a/include/io/channel-socket.h +++ b/include/io/channel-socket.h @@ -261,5 +261,18 @@ QIOChannelSocket * qio_channel_socket_accept(QIOChannelSocket *ioc, Error **errp); +/** + * qio_channel_socket_set_send_buffer: + * @ioc: the socket channel object + * @size: buffer size + * @errp: pointer to a NULL-initialized error object + * + * Set the underlying socket send buffer size. + * + * Retruns: 0 on success, or -1 on error. + */ +int qio_channel_socket_set_send_buffer(QIOChannelSocket *ioc, + size_t size, + Error **errp); #endif /* QIO_CHANNEL_SOCKET_H */ diff --git a/io/channel-socket.c b/io/channel-socket.c index 088b49ffdb..3b7ca924ff 100644 --- a/io/channel-socket.c +++ b/io/channel-socket.c @@ -78,6 +78,17 @@ qio_channel_socket_new(void) return sioc; } +int qio_channel_socket_set_send_buffer(QIOChannelSocket *ioc, + size_t size, + Error **errp) +{ + if (setsockopt(ioc->fd, SOL_SOCKET, SO_SNDBUF, &size, sizeof(size)) < 0) { + error_setg_errno(errp, errno, "Unable to set socket send buffer size"); + return -1; + } + + return 0; +} static int qio_channel_socket_set_fd(QIOChannelSocket *sioc, -- 2.39.5