FreeBSD src
26ab2d1d23
These functions are used a lot for mutexes, so this reduces the text size of an average kernel by about 0.75%. This wasn't intended to be a significant optimization, but it somehow increased the maximum number of packets per second that can be transmitted by my bge hardware from 320000 to 460000 (this benchmark is CPU-bound and remarkably sensitive to changes in the text section). Details: we would prefer to leave the result of the cmpxchg in %al, but cannot tell gcc that it is there, so we have to convert it to an integer register. We converted to %al, then to %[re]ax, but the latter step is usually wasted since gcc usually only wants the condition code and can recover it from %al just as easily as from %[re]ax. Let gcc promote %al in the few cases where this is needed. Nearby style fixes; - let gcc manage the load of `res', and don't abuse `res' for a copy of `exp' - don't echo `res's name in comments - consistently spell the condition code as 'e' after comparison for equality - don't hard-code %al anywhere except in constraints - for the version that doesn't use cmpxchg, there is no requirement to use %al anywhere, so don't hard-code it in the constraints either. Style non-fix: - for the versions that use cmpxchg, keep using "a" (was %[re]ax, now %al) for the main output operand, although this is not required. The input and output operands that use the "a" constraint are now decoupled, and this makes things clearer except for the reason that the output register is hard-coded. It is now just a hack to tell gcc that the input "a" has been clobbered without increasing the number of operands. |
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| bin | ||
| 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