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SENDMMSG(2) | Linux Programmer's Manual | SENDMMSG(2) |
NAME¶
sendmmsg - send multiple messages on a socketSYNOPSIS¶
#define _GNU_SOURCE #include <sys/socket.h> int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags);
DESCRIPTION¶
The sendmmsg() system call is an extension of sendmsg(2) that allows the caller to transmit multiple messages on a socket using a single system call. (This has performance benefits for some applications.)struct mmsghdr { struct msghdr msg_hdr; /* Message header */ unsigned int msg_len; /* Number of bytes transmitted */ };
The msg_hdr field is a msghdr structure, as described in sendmsg(2). The msg_len field is used to return the number of bytes sent from the message in msg_hdr (i.e., the same as the return value from a single sendmsg(2) call).
RETURN VALUE¶
On success, sendmmsg() returns the number of messages sent from msgvec; if this is less than vlen, the caller can retry with a further sendmmsg() call to send the remaining messages.ERRORS¶
Errors are as for sendmsg(2). An error is returned only if no datagrams could be sent.VERSIONS¶
The sendmmsg() system call was added in Linux 3.0. Support in glibc was added in version 2.14.CONFORMING TO¶
sendmmsg() is Linux-specific.NOTES¶
The value specified in vlen is capped to UIO_MAXIOV (1024).SEE ALSO¶
recvmmsg(2), sendmsg(2), socket(2), socket(7)COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2012-02-27 | Linux |