Hi, On Thu, Jul 26, 2012 at 9:46 AM, Ronald S. Bultje <rsbul...@gmail.com> wrote: > On Thu, Jul 26, 2012 at 9:05 AM, Måns Rullgård <m...@mansr.com> wrote: >> "Ronald S. Bultje" <rsbul...@gmail.com> writes: >>> On Thu, Jul 26, 2012 at 7:30 AM, Martin Storsjö <mar...@martin.st> wrote: >>>> On Thu, 26 Jul 2012, Ronald S. Bultje wrote: >>>>> On Thu, Jul 26, 2012 at 2:06 AM, Diego Biurrun <di...@biurrun.de> wrote: >>>>>> On Thu, Jul 26, 2012 at 05:10:10AM +0200, Luca Barbato wrote: >>>>>>> On 07/26/2012 04:27 AM, Ronald S. Bultje wrote: >>>>>>>> From: "Ronald S. Bultje" <rsbul...@gmail.com> >>>>>>>> >>>>>>>> --- >>>>>>>> libswscale/swscale.c | 2 +- >>>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>> >>>>>>> >>>>>>> Ok. >>>>>> >>>>>> >>>>>> No, not OK. This is just a repackaged piece of another patch that >>>>>> has review questions that were never answered. Until those questions >>>>>> are settled, this cannot go in. >>>>> >>>>> >>>>> I've looked at all emails in: >>>>> http://comments.gmane.org/gmane.comp.video.libav.devel/28861 >>>>> >>>>> including yours: >>>>> http://permalink.gmane.org/gmane.comp.video.libav.devel/28871 >>>>> >>>>> and Mans': >>>>> http://permalink.gmane.org/gmane.comp.video.libav.devel/28863 >>>>> >>>>> My original mail has the "fence" part in it (simply ctrl-F in your >>>>> browser), and neither you nor Mans respond to that particular section. >>>>> So I'm lost now. What is the specific comment you want me to respond >>>>> to? >>>> >>>> >>>> http://article.gmane.org/gmane.comp.video.libav.devel/30834 >>> >>> If someone feels like rewriting swscale, I'm all supportive of that >>> effort. For now, sws uses movntq in its inline assembly mmx/3dnow >>> optimizations and we'll have to deal with it until someone changes it >>> not to do that. >>> >>> Doing it in generic code is silly because in practice there is never >>> any advantage to doing movntq. Thus, we should discourage its use. >>> Adding generic versions of sfence does not contribute to that. The >>> whole goal - back when I worked on sws - was to kill all these old >>> mmx/3dnow optimizations and replace with modern sse2/avx, which would >>> mean we don't need a call to sfence anymore anyways. >> >> I'm still missing an explanation of why sfence is needed here other than >> movntq somehow being involved. > > My understanding is that if you use movntq and not sfence, the data > may not be in the destination memory pointer by the time swScale() > returns. > > But I didn't write this code.
Ping. Ronald _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel
