On Tue, Oct 25, 2016 at 05:48:50PM +0200, Henrik Gramner wrote: > On Tue, Oct 25, 2016 at 2:28 PM, <u-9...@aetey.se> wrote: > > It would be nice to look at a benchmarking comparison, to be able to > > see the actual practical performance gain of the decision not to follow > > the ABI. > > Just a quick comparison from adding EMMS to a random MMX function > (from x264, because I happened to have the source for that but not > ffmpeg on this machine and I was too lazy to download it). > > sad_4x4_c: 359 > sad_4x4_mmx: 94 > sad_4x4_mmx (emms): 186
This is unfortunatly not exactly the numbers a user or a packager would need to know. The relevant ones would be what time it takes to actually compress or decompress a given file. (if most of the time is spent calling this very function, then we can extrapolate the numbers to the net result, otherwise we shouldn't) If we nevertheless assume that the net performance is proportional to the numbers above, we learn that omission of MMX acceleration compatible with the standard ABI would lead to 50% performance loss for the ABI-compliant users (pure C instead of compliant MMX). This would be a pity, even if the circle of the users who depend on strict ABI-compliance is limited, for the moment. Regards, Rune _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
