* [FFmpeg-devel] [PATCH] Revert "lavc/sbrdsp: R-V V neg_odd_64"
@ 2024-05-13 16:43 Rémi Denis-Courmont
2024-05-13 17:06 ` Lynne via ffmpeg-devel
0 siblings, 1 reply; 3+ messages in thread
From: Rémi Denis-Courmont @ 2024-05-13 16:43 UTC (permalink / raw)
To: ffmpeg-devel
While this function can easily be written with vectors, it just fails to
get any performance improvement.
For reference, this is a simpler loop-free implementation that does get
better performance than the current one depending on hardware, but still
more or less the same metrics as the C code:
func ff_sbr_neg_odd_64_rvv, zve64x
li a1, 32
addi a0, a0, 7
li t0, 8
vsetvli zero, a1, e8, m2, ta, ma
li t1, 0x80
vlse8.v v8, (a0), t0
vxor.vx v8, v8, t1
vsse8.v v8, (a0), t0
ret
endfunc
This reverts commit d06fd18f8f4c6a81ef94cbb600620d83ad51269d.
---
libavcodec/riscv/sbrdsp_init.c | 5 -----
libavcodec/riscv/sbrdsp_rvv.S | 17 -----------------
2 files changed, 22 deletions(-)
diff --git a/libavcodec/riscv/sbrdsp_init.c b/libavcodec/riscv/sbrdsp_init.c
index f937c47e22..d3bafa961e 100644
--- a/libavcodec/riscv/sbrdsp_init.c
+++ b/libavcodec/riscv/sbrdsp_init.c
@@ -26,7 +26,6 @@
void ff_sbr_sum64x5_rvv(float *z);
float ff_sbr_sum_square_rvv(float (*x)[2], int n);
-void ff_sbr_neg_odd_64_rvv(float *x);
void ff_sbr_autocorrelate_rvv(const float x[40][2], float phi[3][2][2]);
void ff_sbr_hf_gen_rvv(float (*X_high)[2], const float (*X_low)[2],
const float alpha0[2], const float alpha1[2],
@@ -64,9 +63,5 @@ av_cold void ff_sbrdsp_init_riscv(SBRDSPContext *c)
}
c->autocorrelate = ff_sbr_autocorrelate_rvv;
}
-#if __riscv_xlen >= 64
- if ((flags & AV_CPU_FLAG_RVV_I64) && (flags & AV_CPU_FLAG_RVB_ADDR))
- c->neg_odd_64 = ff_sbr_neg_odd_64_rvv;
-#endif
#endif
}
diff --git a/libavcodec/riscv/sbrdsp_rvv.S b/libavcodec/riscv/sbrdsp_rvv.S
index 918c37882f..aba9a28108 100644
--- a/libavcodec/riscv/sbrdsp_rvv.S
+++ b/libavcodec/riscv/sbrdsp_rvv.S
@@ -68,23 +68,6 @@ NOHWF fmv.x.w a0, fa0
ret
endfunc
-#if __riscv_xlen >= 64
-func ff_sbr_neg_odd_64_rvv, zve64x
- li a1, 32
- li t1, 1 << 63
-1:
- vsetvli t0, a1, e64, m8, ta, ma
- vle64.v v8, (a0)
- sub a1, a1, t0
- vxor.vx v8, v8, t1
- vse64.v v8, (a0)
- sh3add a0, t0, a0
- bnez t0, 1b
-
- ret
-endfunc
-#endif
-
func ff_sbr_autocorrelate_rvv, zve32f
vsetvli t0, zero, e32, m4, ta, ma
vmv.v.x v0, zero
--
2.43.0
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [FFmpeg-devel] [PATCH] Revert "lavc/sbrdsp: R-V V neg_odd_64"
2024-05-13 16:43 [FFmpeg-devel] [PATCH] Revert "lavc/sbrdsp: R-V V neg_odd_64" Rémi Denis-Courmont
@ 2024-05-13 17:06 ` Lynne via ffmpeg-devel
2024-05-13 18:56 ` Rémi Denis-Courmont
0 siblings, 1 reply; 3+ messages in thread
From: Lynne via ffmpeg-devel @ 2024-05-13 17:06 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Lynne
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On 13/05/2024 18:43, Rémi Denis-Courmont wrote:
> While this function can easily be written with vectors, it just fails to
> get any performance improvement.
>
> For reference, this is a simpler loop-free implementation that does get
> better performance than the current one depending on hardware, but still
> more or less the same metrics as the C code:
>
> func ff_sbr_neg_odd_64_rvv, zve64x
> li a1, 32
> addi a0, a0, 7
> li t0, 8
> vsetvli zero, a1, e8, m2, ta, ma
> li t1, 0x80
> vlse8.v v8, (a0), t0
> vxor.vx v8, v8, t1
> vsse8.v v8, (a0), t0
> ret
> endfunc
>
> This reverts commit d06fd18f8f4c6a81ef94cbb600620d83ad51269d.
> ---
> libavcodec/riscv/sbrdsp_init.c | 5 -----
> libavcodec/riscv/sbrdsp_rvv.S | 17 -----------------
> 2 files changed, 22 deletions(-)
>
> diff --git a/libavcodec/riscv/sbrdsp_init.c b/libavcodec/riscv/sbrdsp_init.c
> index f937c47e22..d3bafa961e 100644
> --- a/libavcodec/riscv/sbrdsp_init.c
> +++ b/libavcodec/riscv/sbrdsp_init.c
> @@ -26,7 +26,6 @@
>
> void ff_sbr_sum64x5_rvv(float *z);
> float ff_sbr_sum_square_rvv(float (*x)[2], int n);
> -void ff_sbr_neg_odd_64_rvv(float *x);
> void ff_sbr_autocorrelate_rvv(const float x[40][2], float phi[3][2][2]);
> void ff_sbr_hf_gen_rvv(float (*X_high)[2], const float (*X_low)[2],
> const float alpha0[2], const float alpha1[2],
> @@ -64,9 +63,5 @@ av_cold void ff_sbrdsp_init_riscv(SBRDSPContext *c)
> }
> c->autocorrelate = ff_sbr_autocorrelate_rvv;
> }
> -#if __riscv_xlen >= 64
> - if ((flags & AV_CPU_FLAG_RVV_I64) && (flags & AV_CPU_FLAG_RVB_ADDR))
> - c->neg_odd_64 = ff_sbr_neg_odd_64_rvv;
> -#endif
> #endif
> }
> diff --git a/libavcodec/riscv/sbrdsp_rvv.S b/libavcodec/riscv/sbrdsp_rvv.S
> index 918c37882f..aba9a28108 100644
> --- a/libavcodec/riscv/sbrdsp_rvv.S
> +++ b/libavcodec/riscv/sbrdsp_rvv.S
> @@ -68,23 +68,6 @@ NOHWF fmv.x.w a0, fa0
> ret
> endfunc
>
> -#if __riscv_xlen >= 64
> -func ff_sbr_neg_odd_64_rvv, zve64x
> - li a1, 32
> - li t1, 1 << 63
> -1:
> - vsetvli t0, a1, e64, m8, ta, ma
> - vle64.v v8, (a0)
> - sub a1, a1, t0
> - vxor.vx v8, v8, t1
> - vse64.v v8, (a0)
> - sh3add a0, t0, a0
> - bnez t0, 1b
> -
> - ret
> -endfunc
> -#endif
> -
> func ff_sbr_autocorrelate_rvv, zve32f
> vsetvli t0, zero, e32, m4, ta, ma
> vmv.v.x v0, zero
Do you think a 256bit implementation be able to overcome the overhead
and end up being faster?
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [FFmpeg-devel] [PATCH] Revert "lavc/sbrdsp: R-V V neg_odd_64"
2024-05-13 17:06 ` Lynne via ffmpeg-devel
@ 2024-05-13 18:56 ` Rémi Denis-Courmont
0 siblings, 0 replies; 3+ messages in thread
From: Rémi Denis-Courmont @ 2024-05-13 18:56 UTC (permalink / raw)
To: FFmpeg development discussions and patches,
Lynne via ffmpeg-devel, ffmpeg-devel
Cc: Lynne
Le 13 mai 2024 20:06:34 GMT+03:00, Lynne via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> a écrit :
>On 13/05/2024 18:43, Rémi Denis-Courmont wrote:
>> While this function can easily be written with vectors, it just fails to
>> get any performance improvement.
>>
>> For reference, this is a simpler loop-free implementation that does get
>> better performance than the current one depending on hardware, but still
>> more or less the same metrics as the C code:
>>
>> func ff_sbr_neg_odd_64_rvv, zve64x
>> li a1, 32
>> addi a0, a0, 7
>> li t0, 8
>> vsetvli zero, a1, e8, m2, ta, ma
>> li t1, 0x80
>> vlse8.v v8, (a0), t0
>> vxor.vx v8, v8, t1
>> vsse8.v v8, (a0), t0
>> ret
>> endfunc
>>
>> This reverts commit d06fd18f8f4c6a81ef94cbb600620d83ad51269d.
>> ---
>> libavcodec/riscv/sbrdsp_init.c | 5 -----
>> libavcodec/riscv/sbrdsp_rvv.S | 17 -----------------
>> 2 files changed, 22 deletions(-)
>>
>> diff --git a/libavcodec/riscv/sbrdsp_init.c b/libavcodec/riscv/sbrdsp_init.c
>> index f937c47e22..d3bafa961e 100644
>> --- a/libavcodec/riscv/sbrdsp_init.c
>> +++ b/libavcodec/riscv/sbrdsp_init.c
>> @@ -26,7 +26,6 @@
>> void ff_sbr_sum64x5_rvv(float *z);
>> float ff_sbr_sum_square_rvv(float (*x)[2], int n);
>> -void ff_sbr_neg_odd_64_rvv(float *x);
>> void ff_sbr_autocorrelate_rvv(const float x[40][2], float phi[3][2][2]);
>> void ff_sbr_hf_gen_rvv(float (*X_high)[2], const float (*X_low)[2],
>> const float alpha0[2], const float alpha1[2],
>> @@ -64,9 +63,5 @@ av_cold void ff_sbrdsp_init_riscv(SBRDSPContext *c)
>> }
>> c->autocorrelate = ff_sbr_autocorrelate_rvv;
>> }
>> -#if __riscv_xlen >= 64
>> - if ((flags & AV_CPU_FLAG_RVV_I64) && (flags & AV_CPU_FLAG_RVB_ADDR))
>> - c->neg_odd_64 = ff_sbr_neg_odd_64_rvv;
>> -#endif
>> #endif
>> }
>> diff --git a/libavcodec/riscv/sbrdsp_rvv.S b/libavcodec/riscv/sbrdsp_rvv.S
>> index 918c37882f..aba9a28108 100644
>> --- a/libavcodec/riscv/sbrdsp_rvv.S
>> +++ b/libavcodec/riscv/sbrdsp_rvv.S
>> @@ -68,23 +68,6 @@ NOHWF fmv.x.w a0, fa0
>> ret
>> endfunc
>> -#if __riscv_xlen >= 64
>> -func ff_sbr_neg_odd_64_rvv, zve64x
>> - li a1, 32
>> - li t1, 1 << 63
>> -1:
>> - vsetvli t0, a1, e64, m8, ta, ma
>> - vle64.v v8, (a0)
>> - sub a1, a1, t0
>> - vxor.vx v8, v8, t1
>> - vse64.v v8, (a0)
>> - sh3add a0, t0, a0
>> - bnez t0, 1b
>> -
>> - ret
>> -endfunc
>> -#endif
>> -
>> func ff_sbr_autocorrelate_rvv, zve32f
>> vsetvli t0, zero, e32, m4, ta, ma
>> vmv.v.x v0, zero
>
>Do you think a 256bit implementation be able to overcome the overhead and end up being faster?
Based on Sunyeuchi's tests, it gets worse with larger vectors.
I guess the C code is just bound by memory bandwidth, since the "calculations" are so trivial, and thus we can't really beat C here.
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2024-05-13 16:43 [FFmpeg-devel] [PATCH] Revert "lavc/sbrdsp: R-V V neg_odd_64" Rémi Denis-Courmont
2024-05-13 17:06 ` Lynne via ffmpeg-devel
2024-05-13 18:56 ` Rémi Denis-Courmont
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