freebsd kernel with SKQ
f8aee88f0b
LLE structure is mostly unchanged during its lifecycle. To be more specific, there are 2 things relevant for fast path lookup code: 1) link-level address change. Since r286722, these updates are performed under AFDATA WLOCK. 2) Some sort of feedback indicating that this particular entry is used so we re-send arp request to perform reachability verification instead of expiring entry. The only signal that is needed from fast path is something like binary yes/no. The latter is solved by the following changes: 1) introduce special r_skip_req field which is read lockless by fast path, but updated under (new) req_mutex mutex. If this field is non-zero, then fast path will acquire lock and set it back to 0. 2) introduce simple state machine: incomplete->reachable<->verify->deleted. Before that we implicitely had incomplete->reachable->deleted state machine, with V_arpt_keep between "reachable" and "deleted". Verification was performed in runtime 5 seconds before V_arpt_keep expire. This is changed to "change state to verify 5 seconds before V_arpt_keep, set r_skip_req to non-zero value and check it every second". If the value is zero - then send arp verification probe. These changes do not introduce any signifficant control plane overhead: typically lle callout timer would fire 1 time more each V_arpt_keep (1200s) for used lles and up to arp_maxtries (5) for dead lles. As a result, all packets towards "reachable" lle are handled by fast path without acquiring lle read lock. Additional "req_mutex" is needed because callout / arpresolve_slow() or eventhandler might keep LLE lock for signifficant amount of time, which might not be feasible for fast path locking (e.g. having rmlock as ether AFDATA or lltable own lock). Differential Revision: https://reviews.freebsd.org/D3688 |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| 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. See build(7) and 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. See build(7), config(8), and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information. 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 kernel configuration files reside in the sys/<arch>/conf sub-directory. GENERIC is the default configuration used in release builds. NOTES contains entries and documentation for all possible devices, not just those commonly used. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. 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. tests Regression tests which can be run by Kyua. See tests/README for additional information. 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