On 31.5.2013 13:04, Miroslav Lichvar wrote: > On Wed, May 29, 2013 at 04:08:57PM +0200, Martijn van Beurden wrote: >> I was surprised to see that the Windows compile on wine actually >> outperformed the native Linux one. Probably GCC 4.6 optimized a little >> better or something very weird is going on in wine, I don't know. The >> assembly optimizations work very well on encoding, but actually slow >> things down when decoding. The difference is not very large however. > In a quick test with a pre 4.8 gcc on a Core 2 CPU I see a small > improvement in decoding speed with assembly optimizations turned on, > but I think the difference used to be larger. Perhaps the compilers > got better or MMX is slower relative to normal code on current CPUs. > > Disabling the FLAC__bitreader_read_rice_signed_block_asm_ia32_bswap > function seems to help a bit. (there is an #if disabling the function > with comment "OPT: not clearly faster, needs more testing" in the > src/libFLAC/stream_decoder.c file) > > Here is the relative decoding speed with -5 and -8: > -5 -8 > no asm 99.0% 97.0% > asm 100.0% 100.0% > asm (no ia32_bswap) 102.7% 102.7% > > I think we should drop that assembly function as the C > version seems to be faster now. > > Can anyone confirm this? > > Thanks, >
I can confirm. I see 10% speed improvement with that change on Core i7. Decoding a 1h18min38.133s long test FLAC -8 encoded file takes with normal asm optimizations 7.656s (speed: 616,266x realtime) and with that tiny change 6.937s (speed: 680,140x realtime). _______________________________________________ flac-dev mailing list flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
