From: "Rémi Denis-Courmont" <remi@remlab.net>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCHv2 0/10] RISC-V V floating point DSP
Date: Sun, 04 Sep 2022 22:01:07 +0300
Message-ID: <1800222.atdPhlSkOF@basile.remlab.net> (raw)
In-Reply-To: <NB8bYGA--3-2@lynne.ee>
Le sunnuntaina 4. syyskuuta 2022, 20.48.26 EEST Lynne a écrit :
> > The pointer arithmetic could be slightly optimised with SH2ADD and
> > SH3ADD instructions from the Zvba extension. This would require more
> > conditional code, or requiring support for Zvba for probably neglible
> > performance gains though.
>
> Did you test on real hardware or a VM?
I don't think we will see real and conforming RV64GV hardware this year,
unless you count FPGAs. I hope we can get affordable stuff in 2023H1.
This is running on simulator. But since the code is already (AFAICT) using the
largest possible grouping, there won't be that much room for further
optimisations, other maybe than to add prefetching hints. In that sense, RVV
is really nice in how it makes unrolling almost unnecessary/effortless.
The code is also already laid out to leverage multiple issue if available.
RISC-V does not have post-index addressing modes, so the interleaving a fair
amount of pointer arithmetic is unavoidable.
> If the former, what does checkasm --bench report?
...
--
雷米‧德尼-库尔蒙
http://www.remlab.net/
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prev parent reply other threads:[~2022-09-04 19:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-04 13:54 Rémi Denis-Courmont
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 01/10] riscv: add CPU flags for the RISC-V Vector extension remi
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 02/10] riscv: initial common header for assembler macros remi
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 03/10] riscv: float vector-scalar multiplication with RVV remi
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 04/10] riscv: float vector-vector " remi
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 05/10] riscv: float vector multiply-accumulate " remi
2022-09-04 13:54 ` [FFmpeg-devel] [PATCH 06/10] riscv: float vector multiplication-addition " remi
2022-09-04 13:55 ` [FFmpeg-devel] [PATCH 07/10] riscv: float vector sum-and-difference " remi
2022-09-04 13:55 ` [FFmpeg-devel] [PATCH 08/10] riscv: float reversed vector multiplication " remi
2022-09-04 13:55 ` [FFmpeg-devel] [PATCH 09/10] riscv: float vector windowed overlap/add " remi
2022-09-04 13:55 ` [FFmpeg-devel] [PATCH 10/10] riscv: float vector dot product " remi
2022-09-04 17:48 ` [FFmpeg-devel] [PATCHv2 0/10] RISC-V V floating point DSP Lynne
2022-09-04 19:01 ` Rémi Denis-Courmont [this message]
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