Re: [FFmpeg-devel] [PATCH v3] avcodec/mathops: Optimize generic mid_pred function

[Michael Niedermayer <michael@niedermayer.cc>]

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On Wed, Mar 15, 2023 at 06:09:13PM +0800, YunQiang Su wrote:
> Michael Niedermayer <michael@niedermayer.cc> 于2023年3月8日周三 04:45写道：
> >
> > On Tue, Mar 07, 2023 at 05:08:27PM +0800, Junxian Zhu wrote:
> > > From: Junxian Zhu <zhujunxian@oss.cipunited.com>
> > >
> > > Rewrite mid_pred function in generic mathops.h, reduce branch jump to improve performance. And because nowadays new version compiler can compile enough short asmbbely code as handwritting in these function, so remove specified optimized mips inline asmbbely mathops.h.
> >
> > as you write, that it improves performance
> > what speed effect does this have exactly?
> > thx
> >
> 
> I tested the performance, using this code
[...]
> On MacOS 13.2 with Apple M1:
> The old code              the new code
> 2.1s                            2.3s
> 
> On Cavium ThunderX / arm64 (GCC 10.2.1 -O3)
> The old code              the new code
> 52.7s                          37.8s
> 
> On Loongson 3A4000/mips64el (GCC 10.2.1 -O3)
> The old code              the new code
> 90s                             5s
> 
> On Intel(R) Xeon(R) CPU E7-4820 v4 @ 2.00GHz (GCC 10.2.1 -O3)
> The old code              the new code
> 14.4s                          15.4s
> 
> On SF19A2890/MIPS interAptiv (GCC 10.2.1 -O3)
> The old code              the new code
> 314s                           39.3s
> 
> On Intel(R) Xeon(R) CPU E7-4820 v4 @ 2.00GHz (GCC 12.2.0 -O3)
> The old code              the new code
> 14.4s                          8.8s
> 
> On sifive,bullet0/rv64imafdc  (GCC 12.2.0 -O3, 1e6 times instead of 1e7)
> The old code              the new code
> 11.9s                          15.2s
> 
> On Freescale i.MX53/ARMv7 Processor rev 5 (v7l)  (GCC 12.2.0 -O3, 1e6
> times instead of 1e7)
> The old code              the new code
> 24.1s                          15.7s
> 
> On POWER8 (architected), altivec supported, BIG ENDIAN, ppc64  (GCC 12.2.0 -O3)
> The old code              the new code
> 43.1s                          50.8s
> 
> On POWER8 (architected), altivec supported, LITTLE ENDIAN, ppc64el
> (GCC 12.2.0 -O3)
> The old code              the new code
> 7.8s                            4.7s
> 
> On PA8900 (Shortfin) PA-RISC (GCC 12.2.0 -O3 1e6 times instead of 1e7)
> The old code              the new code
> 39.9s                          47.2s
> 
> On IBM/S390 aka s390x (GCC 12.2.0 -O3)
> The old code              the new code
> 82.2s                          30.8s
> 
> On Intel(R)  Itanium(R)  Processor 9320  (GCC 12.2.0 -O3)
> The old code              the new code
> 89.5s                          78.1s
> 
> Cavium Octeon III V0.2  FPU V0.0 /mipsel  (GCC 12.2.0 -O3)
> The old code              the new code
> 117.5s                        118.5s

These cover a quite extensive set of hw, impressive

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship: All citizens are under surveillance, all their steps and
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