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code for reading from the frame buffer. Reading from the frame buffer is usually much slower than writing to the frame buffer. Typically 10 to 100 times slower. It old modes, it takes many more PIOs, and in newer modes with no PIOs writes are often write-combined while reads remain uncached. Reading from the frame buffer is not very common, so this change doesn't give speedups of 10 to 100 times. My main test case is a floodfill() function that reads about as many pixels as it writes. The speedups are typically a factor of 2 to 4. Duplicating writes to the shadow buffer is slower when no reads from the frame buffer are done, but reads are often done for the pixels under the mouse cursor, and doing these reads from the shadow buffer more than compensates for the overhead of writing the shadow buffer in at least the slower modes. Management of the mouse cursor also becomes simpler. The shadow buffer doesn't take any extra memory, except twice as much in old 4-plane modes. A buffer for holding a copy of the frame buffer was allocated up front for use in the screen switching signal handler. This wasn't changed when the handler was made async-signal safe. Use the same buffer the shadow (but make it twice as large in the 4-plane modes), and remove large special code for writing it as well as large special code for reading ut. It used to have a rawer format in the 4-plane modes. Now it has a bitmap format which takes twice as much memory but can be written almost as fast without special code. VIDBUFs that are not the whole frame buffer were never supported, and the change depends on this. Check for invalid VIDBUFs in some places and do nothing. The removed code did something not so good. |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .cirrus.yml | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
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), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
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.
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.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
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:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html