On Mon, 2016-07-04 at 16:30 +0000, Carl Eugen Hoyos wrote: > Dan Parrot <dan.parrot <at> mail.com> writes: > > > > Did you test if using ffmpeg -benchmark -f rawvideo -i /dev/zero... > > > showed different results? > > > I believe this should be both easier and faster to test. > > > > Sorry, I don't understand what that command line just above > > is trying to achieve. Could you elaborate? > > Instead of running the whole fate suite that takes long and > does not test libswscale for most commands, just test an > ffmpeg command line that only tests libswscale: > $ ffmpeg -benchmark -f rawvideo -pix_fmt rgb24 > -i /dev/zero -pix_fmt yuv420p -f null -vframes 10000 - > vs > > $ ffmpeg -cpuflags 0 -benchmark -f rawvideo -pix_fmt rgb24 > -i /dev/zero -pix_fmt yuv420p -f null -vframes 10000 - > Ok. Thanks for the explanation. I will run those commands and post the reported results.
> [...] > > > Surprisingly, gcc is producing some badly suboptimal assembly. > > Just to make sure I don't misunderstand: > Does this mean intrinsics are suboptimal to write assembly > code? Here's what I mean: All variables below are of type "vector int" 1. v0 = v2 * v3 2. v0 = v4 * v5 + v6 * v7 + v8 * v9 The first statement produces 1 multiply, 1 multiply-sum and 1 addition instruction in assembly. The second produces 6 multiply, 6 multiply-sum, and 10 addition instructions in assembly! I expected 3, 3, 3 of each respective operations from (1) plus 2 additions. > > > > Can you confirm with START_TIMER / STOP_TIMER that there is no > > > gain? > > > > SystemTap probes provide identical functionality by measuring > > deltas between function entry and function return. > > Sorry, I don't understand: > Did you test with both methods to verify that they provide > the same results? > > Note that if it turns out that START_TIMER / STOP_TIMER > cannot be used on ppc64 (le) this would be important > information for us. > I'll insert these macros and inform of the results if the code compiles and runs. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
