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lavu/riscv: Revert d808070, removing AV_READ_TIME

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The implementation of ff_read_time() for RISC-V uses rdtime which has
 precision on existing hardware too low (!) for benchmarking purposes.
Deleting this implementation falls back on clock_gettime() which was
 added as the default ff_read_time() implementation in 33e4cc9.
Below are metrics gathered on SpacemiT K1, before and after this commit:

Before:

$ tests/checkasm/checkasm --bench
benchmarking with native FFmpeg timers
nop: 0.0
checkasm: using random seed 3473665261
checkasm: bench runs 1024 (1 << 10)
RVI:
 - pixblockdsp.get_pixels                [OK]
 - vc1dsp.mspel_pixels                   [OK]
RVF:
 - audiodsp.audiodsp                     [OK]
checkasm: all 4 tests passed
audiodsp.vector_clipf_c: 1388.7
audiodsp.vector_clipf_rvf: 261.5
get_pixels_c: 2.0
get_pixels_rvi: 1.5
vc1dsp.put_vc1_mspel_pixels_tab[0][0]_c: 8.0
vc1dsp.put_vc1_mspel_pixels_tab[0][0]_rvi: 1.0
vc1dsp.put_vc1_mspel_pixels_tab[1][0]_c: 2.0
vc1dsp.put_vc1_mspel_pixels_tab[1][0]_rvi: 0.5

After:

$ tests/checkasm/checkasm --bench
benchmarking with native FFmpeg timers
nop: 56.4
checkasm: using random seed 1021411603
checkasm: bench runs 1024 (1 << 10)
RVI:
 - pixblockdsp.get_pixels                [OK]
 - vc1dsp.mspel_pixels                   [OK]
RVF:
 - audiodsp.audiodsp                     [OK]
checkasm: all 4 tests passed
audiodsp.vector_clipf_c: 23236.4
audiodsp.vector_clipf_rvf: 11038.4
get_pixels_c: 79.6
get_pixels_rvi: 48.4
vc1dsp.put_vc1_mspel_pixels_tab[0][0]_c: 329.6
vc1dsp.put_vc1_mspel_pixels_tab[0][0]_rvi: 38.1
vc1dsp.put_vc1_mspel_pixels_tab[1][0]_c: 89.9
vc1dsp.put_vc1_mspel_pixels_tab[1][0]_rvi: 17.1

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
This commit is contained in:
Nathan E. Egge 2024-07-28 17:10:51 +00:00 committed by Rémi Denis-Courmont
parent ab5c612137
commit 8280ec7a32
2 changed files with 0 additions and 56 deletions
libavutil
riscv
timer.h
timer.h

54
libavutil/riscv/timer.h

@ -1,54 +0,0 @@
/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_RISCV_TIMER_H
#define AVUTIL_RISCV_TIMER_H
#include "config.h"
#if HAVE_INLINE_ASM
#include <stdint.h>
static inline uint64_t ff_read_time(void)
{
#if (__riscv_xlen >= 64)
uintptr_t cycles;
__asm__ volatile ("rdtime %0" : "=r" (cycles));
#else
uint64_t cycles;
uint32_t hi, lo, check;
__asm__ volatile (
"1: rdtimeh %0\n"
" rdtime %1\n"
" rdtimeh %2\n"
" bne %0, %2, 1b\n" : "=r" (hi), "=r" (lo), "=r" (check));
cycles = (((uint64_t)hi) << 32) | lo;
#endif
return cycles;
}
#define AV_READ_TIME ff_read_time
#define FF_TIMER_UNITS "ticks"
#endif
#endif /* AVUTIL_RISCV_TIMER_H */

2
libavutil/timer.h

@ -61,8 +61,6 @@
# include "arm/timer.h"
#elif ARCH_PPC
# include "ppc/timer.h"
#elif ARCH_RISCV
# include "riscv/timer.h"
#elif ARCH_X86
# include "x86/timer.h"
#elif ARCH_LOONGARCH