freebsd with flexible iflib nic queues
bb520069ca
inbound data waiting on a filedescriptor, such as a pipe or a socket, for instance by using select(2), poll(2), kqueue(2), ioctl(FIONREAD) etc. But we have no way of finding out if written data have yet to be disposed of, for instance, transmitted (and ack'ed!) to some remote host, or read by the applicantion at the far end of the pipe. The closest we get, is calling shutdown(2) on a TCP socket in non-blocking mode, but this has the undesirable sideeffect of preventing future communication. Add a complement to FIONREAD, called FIONWRITE, which returns the number of bytes not yet properly disposed of. Implement it for all sockets. Background: A HTTP server will want to time out connections, if no new request arrives within a certain period after the last transmitted response has actually been sent (and ack'ed). For a busy HTTP server, this timeout can be subsecond duration. In order to signal to a load-balancer that the connection is truly dead, TCP_RST will be the preferred method, as this avoids the need for a RTT delay for FIN handshaking, with a client which, surprisingly often, no longer at the remote IP number. If a slow, distant client is being served a response which is big enough to fill the window, but small enough to fit in the socket buffer, the write(2) call will return immediately. If the session timeout is armed at that time, all bytes in the response may not have been transmitted by the time it fires. FIONWRITE allows the timeout to check that no data is outstanding on the connection, before it TCP_RST's it. Input & Idea from: rwatson Approved by: re (kib) |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html