freebsd kernel with SKQ
2043aec456
and remove all O(N) sequences from kernel critical sections in ipfw.
In detail:
1. introduce a IPFW_UH_LOCK to arbitrate requests from
the upper half of the kernel. Some things, such as 'ipfw show',
can be done holding this lock in read mode, whereas insert and
delete require IPFW_UH_WLOCK.
2. introduce a mapping structure to keep rules together. This replaces
the 'next' chain currently used in ipfw rules. At the moment
the map is a simple array (sorted by rule number and then rule_id),
so we can find a rule quickly instead of having to scan the list.
This reduces many expensive lookups from O(N) to O(log N).
3. when an expensive operation (such as insert or delete) is done
by userland, we grab IPFW_UH_WLOCK, create a new copy of the map
without blocking the bottom half of the kernel, then acquire
IPFW_WLOCK and quickly update pointers to the map and related info.
After dropping IPFW_LOCK we can then continue the cleanup protected
by IPFW_UH_LOCK. So userland still costs O(N) but the kernel side
is only blocked for O(1).
4. do not pass pointers to rules through dummynet, netgraph, divert etc,
but rather pass a <slot, chain_id, rulenum, rule_id> tuple.
We validate the slot index (in the array of #2) with chain_id,
and if successful do a O(1) dereference; otherwise, we can find
the rule in O(log N) through <rulenum, rule_id>
All the above does not change the userland/kernel ABI, though there
are some disgusting casts between pointers and uint32_t
Operation costs now are as follows:
Function Old Now Planned
-------------------------------------------------------------------
+ skipto X, non cached O(N) O(log N)
+ skipto X, cached O(1) O(1)
XXX dynamic rule lookup O(1) O(log N) O(1)
+ skipto tablearg O(N) O(1)
+ reinject, non cached O(N) O(log N)
+ reinject, cached O(1) O(1)
+ kernel blocked during setsockopt() O(N) O(1)
-------------------------------------------------------------------
The only (very small) regression is on dynamic rule lookup and this will
be fixed in a day or two, without changing the userland/kernel ABI
Supported by: Valeria Paoli
MFC after: 1 month
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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