diff options
| author | Michael Niedermayer <michaelni@gmx.at> | 2008-01-22 14:48:02 +0000 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2008-01-22 14:48:02 +0000 |
| commit | 5e123bd359226afe7123540e6438a72306c75a2e (patch) | |
| tree | c4002ed380d9232a0938486dd059ab7f9475a879 | |
| parent | 8f738eea4373cdb5b7c3bb42739d2b98aabac34d (diff) | |
| download | ffmpeg-5e123bd359226afe7123540e6438a72306c75a2e.tar.gz | |
Cosmetics to speed up finding sections of interest.
Originally committed as revision 11596 to svn://svn.ffmpeg.org/ffmpeg/trunk
| -rw-r--r-- | doc/optimization.txt | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/doc/optimization.txt b/doc/optimization.txt index 61dc5c40a6..f6033402bb 100644 --- a/doc/optimization.txt +++ b/doc/optimization.txt @@ -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 |