2018-03-18 19:04 GMT+01:00, Paul B Mahol <one...@gmail.com>: > On 3/18/18, Carl Eugen Hoyos <ceffm...@gmail.com> wrote: >> 2018-03-18 18:20 GMT+01:00, Paul B Mahol <one...@gmail.com>: >>> On 3/18/18, Carl Eugen Hoyos <ceffm...@gmail.com> wrote: >>>> 2018-03-18 17:46 GMT+01:00, Martin Vignali <martin.vign...@gmail.com>: >>>>> 2018-03-18 17:37 GMT+01:00 Paul B Mahol <one...@gmail.com>: >>>>> >>>>>> On 3/18/18, Nicolas George <geo...@nsup.org> wrote: >>>>>> > Martin Vignali (2018-03-18): >>>>>> >> I run the test again with a bigger width (512 instead of 128) >>>>>> >> This is my result : >>>>>> >> shuffle_bytes_0321_c: 128.6 >>>>>> >> shuffle_bytes_0321_ssse3: 41.6 >>>>>> >> shuffle_bytes_0321_avx2: 23.4 >>>>>> > >>>>>> > IIUC, these benchmarks are expressed in CPU cycles. But what James >>>>>> > says >>>>>> > is that it can cause the CPU frequency to be throttled: if that >>>>>> > happens, >>>>>> > less cycles can use more time, and even worse, cause other unrelated >>>>>> > to >>>>>> > take more time. A benchmark in actual time and typical use case >>>>>> > would >>>>>> > be >>>>>> > needed to decide. >>>>>> >>>>>> Yes, always also test overall with typical code usecase. >>>> >>>> +1 >>>> >>>>> I tested it using a "benchmark" command line, who test two shuffle func >>>>> ./ffmpeg -benchmark -f lavfi -i rgbtestsrc=size=3840x2160:duration=10 >>>>> -vf >>>>> format=argb,format=rgba -f null - >>>>> >>>>> With the patch : >>>>> bench: utime=3.611s >>>>> With only SSSE 3 (disable AVX2 part), i have similar result. >>>> >>>> Indicating James' original comment that the avx2 optimization >>>> makes no sense is correct? >>> >>> You are almost always wrong. >> >> I tend to agree but I wonder how you know that I am wrong here: >> What in above mail indicates that avx2 has an advantage over >> ssse3? > > It might work with new CPUs much better.
"might" indicates that I am wrong? Your reasoning is not much better than mine... Carl Eugen _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
