> > # detect extensions > > # Requires intrinsics available in GCC 14.1.0+ and
> > Clang 18.1.0+ > > if (riscv_extension_macros and > >
> > (cc.get_define('__riscv_zicbop', args: machine_args) != '')) > > if
> > ((cc.get_id() == 'gcc' and cc.version().version_compare('>=14.1.0')) > >
> > or (cc.get_id() == 'clang' and
> > cc.version().version_compare('>=18.1.0'))) > > message('Compiling
> > with the zicbop extension') > > machine_args +=
> > ['-DRTE_RISCV_FEATURE_PREFETCH'] > > else > > warning('Detected
> > zicbop extension but cannot use because intrinsics are not available
> > (present in GCC 14.1.0+ and Clang 18.1.0+)') > > endif > > endif > > The
> > implementation does not involve intrinsicsIt looks like nothing has been
> > changed here yet.--------------sorry, i did not notice this. i'll revise
> > it later.
With the current compilation conditions, if zicbop isn’t supported, the
v-optimization also won’t be compiled.Have you tested the performance
difference if you remove these prefetches and only use v?
----------------yes. when we use vector but without zicbop, the
performance is worse than memcpy.Can we use a condition like this to support
only v?---------Since the code affects several areas and for the reason
mentioned above, I prefer to keep the current logic, as it looks simpler.
Thanks again for your review.
Original
From: sunyuechi <[email protected]>
To: 陈其国10108961;[email protected]
<[email protected]>;[email protected]
<[email protected]>;
Cc: [email protected] <[email protected]>;[email protected]
<[email protected]>;
Date: 2025年11月17日 12:19
Subject: Re: [PATCH v6 1/1] eal/riscv: optimize rte_memcpy with vector and
zicbop extensions
> > # detect extensions
> > # Requires intrinsics available in GCC 14.1.0+ and Clang 18.1.0+
> > if (riscv_extension_macros and
> > (cc.get_define('__riscv_zicbop', args: machine_args) != ''))
> > if ((cc.get_id() == 'gcc' and
cc.version().version_compare('>=14.1.0'))
> > or (cc.get_id() == 'clang' and
cc.version().version_compare('>=18.1.0')))
> > message('Compiling with the zicbop extension')
> > machine_args += ['-DRTE_RISCV_FEATURE_PREFETCH']
> > else
> > warning('Detected zicbop extension but cannot use because
intrinsics are not available (present in GCC 14.1.0+ and Clang 18.1.0+)')
> > endif
> > endif
>
> The implementation does not involve intrinsics
It looks like nothing has been changed here yet.
> #if defined(RTE_RISCV_FEATURE_V) &&
!(defined(RTE_RISCV_FEATURE_PREFETCH))
> #undef RTE_RISCV_FEATURE_V
> #endif
>
> static __rte_always_inline void
> _rte_mov128blocks(uint8_t *dst, const uint8_t *src, size_t n)
> {
> asm volatile (
> "prefetch.r 64(%1)\n"
> "prefetch.w 64(%0)\n"
> "prefetch.r 128(%1)\n"
> "prefetch.w 128(%0)\n"
> "prefetch.r 192(%1)\n"
> "prefetch.w 192(%0)\n"
> "prefetch.r 256(%1)\n"
> "prefetch.w 256(%0)\n"
> "prefetch.r 320(%1)\n"
> "prefetch.w 320(%0)\n"
> "prefetch.r 384(%1)\n"
> "prefetch.w 384(%0)\n"
> "prefetch.r 448(%1)\n"
> "prefetch.w 448(%0)\n"
> "prefetch.r 512(%1)\n"
> "li t6, 512\n"
> "3:\n"
> "li t5, 128;"
> "vsetvli zero, t5, e8, m8, ta, ma\n"
With the current compilation conditions, if zicbop isn’t supported, the
v-optimization also won’t be compiled.
Have you tested the performance difference if you remove these
prefetches and only use v?
Can we use a condition like this to support only v?
#if defined(RTE_RISCV_FEATURE_V)
#if (defined(RTE_RISCV_FEATURE_PREFETCH))
...
#endif
...
#endif
