Update of /b/source/CVS/src/sys/kern
In directory sun-lamp.cs.berkeley.edu:/e/users/cgd/trees/all/src/sys/kern

Modified Files:
	uipc_socket.c 
Log Message:
fix from david greenman, davidg@freefall.cdrom.com:
sosend was attempting to reserve space in an mbuf cluster for a datagram
header and because of bugs in the sosend's mbuf allocation algorithm, 
sosend was calling uiomove twice as many times as was necessary. It turns
out that PREPEND does the right thing when a cluster is associated with
an mbuf header, so the datagram header allocation can be defered. This
also ends up additionally consuming one less mbuf for the TCP protocol
because TCP always allocates another header mbuf regardless if space is
available to prepend the protocol header. The net result of this fix is
that unix domain and pipe throughput is increased by a measured 10%.


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