generic-library/ffmpeg
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Cosmetics to speed up finding sections of interest.

Browse Source 
Originally committed as revision 11596 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2008-01-22 14:48:02 +00:00
parent 8f738eea43
commit 5e123bd359
1 changed files with 13 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
doc/optimization.txt
View File

@ -1,6 +1,8 @@
optimization Tips (for libavcodec):
===================================
What to optimize:
-----------------
If you plan to do non-x86 architecture specific optimizations (SIMD normally),
then take a look in the i386/ directory, as most important functions are
already optimized for MMX.
@ -9,7 +11,9 @@ If you want to do x86 optimizations then you can either try to finetune the
stuff in the i386 directory or find some other functions in the C source to
optimize, but there aren't many left.
Understanding these overoptimized functions:
--------------------------------------------
As many functions tend to be a bit difficult to understand because
of optimizations, it can be hard to optimize them further, or write
architecture-specific versions. It is recommened to look at older
@ -23,7 +27,9 @@ and how they can be optimized.
NOTE: If you still don't understand some function, ask at our mailing list!!!
(http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel)
What speedup justifies an optimizetion?
---------------------------------------
Normaly with clean&simple optimizations and widely used codecs a overall
speedup of the affected codec of 0.1% is enough. These speedups accumulate
and can make a big difference after a while ...
@ -35,6 +41,7 @@ small and readable than to make it 1% faster.
WTF is that function good for ....:
-----------------------------------
The primary purpose of that list is to avoid wasting time to optimize functions
which are rarely used
@ -145,9 +152,11 @@ The minimum guaranteed alignment is written in the .h files, for example:
Links:
======
http://www.aggregate.org/MAGIC/
x86-specific:
-------------
http://developer.intel.com/design/pentium4/manuals/248966.htm
The IA-32 Intel Architecture Software Developer's Manual, Volume 2:
@ -161,7 +170,7 @@ http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/22007.pd
ARM-specific:
-------------
ARM Architecture Reference Manual (up to ARMv5TE):
http://www.arm.com/community/university/eulaarmarm.html
@ -176,7 +185,7 @@ Optimization guide for Intel XScale (used in Sharp Zaurus PDA):
http://download.intel.com/design/intelxscale/27347302.pdf
PowerPC-specific:
-----------------
PowerPC32/AltiVec PIM:
www.freescale.com/files/32bit/doc/ref_manual/ALTIVECPEM.pdf
@ -188,6 +197,7 @@ http://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/30B3520C93F437AB8725706
http://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/9F820A5FFA3ECE8C8725716A0062585F/$file/CBE_Handbook_v1.1_24APR2007_pub.pdf
SPARC-specific:
---------------
SPARC Joint Programming Specification (JPS1): Commonality
http://www.fujitsu.com/downloads/PRMPWR/JPS1-R1.0.4-Common-pub.pdf
@ -198,6 +208,7 @@ VIS Whitepaper (contains optimization guidelines)
http://www.sun.com/processors/vis/download/vis/vis_whitepaper.pdf
GCC asm links:
--------------
official doc but quite ugly
http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html