[dpdk-dev] [PATCH v2 4/4] lib/librte_eal: Optimized memcpy in arch/x86/rte_memcpy.h for both SSE and AVX platforms

Wang, Zhihong zhihong.wang at intel.com
Fri Jan 30 06:57:17 CET 2015


Hey Konstantin,

This method does reduce code size but lead to significant performance drop.
I think we need to keep the original code.


Thanks
Zhihong (John)


> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Thursday, January 29, 2015 11:18 PM
> To: Wang, Zhihong; dev at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v2 4/4] lib/librte_eal: Optimized memcpy in
> arch/x86/rte_memcpy.h for both SSE and AVX platforms
> 
> Hi Zhihong,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Zhihong Wang
> > Sent: Thursday, January 29, 2015 2:39 AM
> > To: dev at dpdk.org
> > Subject: [dpdk-dev] [PATCH v2 4/4] lib/librte_eal: Optimized memcpy in
> > arch/x86/rte_memcpy.h for both SSE and AVX platforms
> >
> > Main code changes:
> >
> > 1. Differentiate architectural features based on CPU flags
> >
> >     a. Implement separated move functions for SSE/AVX/AVX2 to make
> > full utilization of cache bandwidth
> >
> >     b. Implement separated copy flow specifically optimized for target
> > architecture
> >
> > 2. Rewrite the memcpy function "rte_memcpy"
> >
> >     a. Add store aligning
> >
> >     b. Add load aligning based on architectural features
> >
> >     c. Put block copy loop into inline move functions for better
> > control of instruction order
> >
> >     d. Eliminate unnecessary MOVs
> >
> > 3. Rewrite the inline move functions
> >
> >     a. Add move functions for unaligned load cases
> >
> >     b. Change instruction order in copy loops for better pipeline
> > utilization
> >
> >     c. Use intrinsics instead of assembly code
> >
> > 4. Remove slow glibc call for constant copies
> >
> > Signed-off-by: Zhihong Wang <zhihong.wang at intel.com>
> > ---
> >  .../common/include/arch/x86/rte_memcpy.h           | 680
> +++++++++++++++------
> >  1 file changed, 509 insertions(+), 171 deletions(-)
> >
> > diff --git a/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
> > b/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
> > index fb9eba8..7b2d382 100644
> > --- a/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
> > +++ b/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
> > @@ -34,166 +34,189 @@
> >  #ifndef _RTE_MEMCPY_X86_64_H_
> >  #define _RTE_MEMCPY_X86_64_H_
> >
> > +/**
> > + * @file
> > + *
> > + * Functions for SSE/AVX/AVX2 implementation of memcpy().
> > + */
> > +
> > +#include <stdio.h>
> >  #include <stdint.h>
> >  #include <string.h>
> > -#include <emmintrin.h>
> > +#include <x86intrin.h>
> >
> >  #ifdef __cplusplus
> >  extern "C" {
> >  #endif
> >
> > -#include "generic/rte_memcpy.h"
> > +/**
> > + * Copy bytes from one location to another. The locations must not
> overlap.
> > + *
> > + * @note This is implemented as a macro, so it's address should not
> > +be taken
> > + * and care is needed as parameter expressions may be evaluated
> multiple times.
> > + *
> > + * @param dst
> > + *   Pointer to the destination of the data.
> > + * @param src
> > + *   Pointer to the source data.
> > + * @param n
> > + *   Number of bytes to copy.
> > + * @return
> > + *   Pointer to the destination data.
> > + */
> > +static inline void *
> > +rte_memcpy(void *dst, const void *src, size_t n)
> > +__attribute__((always_inline));
> >
> > -#ifdef __INTEL_COMPILER
> > -#pragma warning(disable:593) /* Stop unused variable warning (reg_a
> > etc). */ -#endif
> > +#ifdef RTE_MACHINE_CPUFLAG_AVX2
> >
> > +/**
> > + * AVX2 implementation below
> > + */
> > +
> > +/**
> > + * Copy 16 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> >  static inline void
> >  rte_mov16(uint8_t *dst, const uint8_t *src)  {
> > -	__m128i reg_a;
> > -	asm volatile (
> > -		"movdqu (%[src]), %[reg_a]\n\t"
> > -		"movdqu %[reg_a], (%[dst])\n\t"
> > -		: [reg_a] "=x" (reg_a)
> > -		: [src] "r" (src),
> > -		  [dst] "r"(dst)
> > -		: "memory"
> > -	);
> > +	__m128i xmm0;
> > +
> > +	xmm0 = _mm_loadu_si128((const __m128i *)src);
> > +	_mm_storeu_si128((__m128i *)dst, xmm0);
> >  }
> >
> > +/**
> > + * Copy 32 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> >  static inline void
> >  rte_mov32(uint8_t *dst, const uint8_t *src)  {
> > -	__m128i reg_a, reg_b;
> > -	asm volatile (
> > -		"movdqu (%[src]), %[reg_a]\n\t"
> > -		"movdqu 16(%[src]), %[reg_b]\n\t"
> > -		"movdqu %[reg_a], (%[dst])\n\t"
> > -		"movdqu %[reg_b], 16(%[dst])\n\t"
> > -		: [reg_a] "=x" (reg_a),
> > -		  [reg_b] "=x" (reg_b)
> > -		: [src] "r" (src),
> > -		  [dst] "r"(dst)
> > -		: "memory"
> > -	);
> > -}
> > +	__m256i ymm0;
> >
> > -static inline void
> > -rte_mov48(uint8_t *dst, const uint8_t *src) -{
> > -	__m128i reg_a, reg_b, reg_c;
> > -	asm volatile (
> > -		"movdqu (%[src]), %[reg_a]\n\t"
> > -		"movdqu 16(%[src]), %[reg_b]\n\t"
> > -		"movdqu 32(%[src]), %[reg_c]\n\t"
> > -		"movdqu %[reg_a], (%[dst])\n\t"
> > -		"movdqu %[reg_b], 16(%[dst])\n\t"
> > -		"movdqu %[reg_c], 32(%[dst])\n\t"
> > -		: [reg_a] "=x" (reg_a),
> > -		  [reg_b] "=x" (reg_b),
> > -		  [reg_c] "=x" (reg_c)
> > -		: [src] "r" (src),
> > -		  [dst] "r"(dst)
> > -		: "memory"
> > -	);
> > +	ymm0 = _mm256_loadu_si256((const __m256i *)src);
> > +	_mm256_storeu_si256((__m256i *)dst, ymm0);
> >  }
> >
> > +/**
> > + * Copy 64 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> >  static inline void
> >  rte_mov64(uint8_t *dst, const uint8_t *src)  {
> > -	__m128i reg_a, reg_b, reg_c, reg_d;
> > -	asm volatile (
> > -		"movdqu (%[src]), %[reg_a]\n\t"
> > -		"movdqu 16(%[src]), %[reg_b]\n\t"
> > -		"movdqu 32(%[src]), %[reg_c]\n\t"
> > -		"movdqu 48(%[src]), %[reg_d]\n\t"
> > -		"movdqu %[reg_a], (%[dst])\n\t"
> > -		"movdqu %[reg_b], 16(%[dst])\n\t"
> > -		"movdqu %[reg_c], 32(%[dst])\n\t"
> > -		"movdqu %[reg_d], 48(%[dst])\n\t"
> > -		: [reg_a] "=x" (reg_a),
> > -		  [reg_b] "=x" (reg_b),
> > -		  [reg_c] "=x" (reg_c),
> > -		  [reg_d] "=x" (reg_d)
> > -		: [src] "r" (src),
> > -		  [dst] "r"(dst)
> > -		: "memory"
> > -	);
> > +	rte_mov32((uint8_t *)dst + 0 * 32, (const uint8_t *)src + 0 * 32);
> > +	rte_mov32((uint8_t *)dst + 1 * 32, (const uint8_t *)src + 1 * 32);
> >  }
> >
> > +/**
> > + * Copy 128 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> >  static inline void
> >  rte_mov128(uint8_t *dst, const uint8_t *src)  {
> > -	__m128i reg_a, reg_b, reg_c, reg_d, reg_e, reg_f, reg_g, reg_h;
> > -	asm volatile (
> > -		"movdqu (%[src]), %[reg_a]\n\t"
> > -		"movdqu 16(%[src]), %[reg_b]\n\t"
> > -		"movdqu 32(%[src]), %[reg_c]\n\t"
> > -		"movdqu 48(%[src]), %[reg_d]\n\t"
> > -		"movdqu 64(%[src]), %[reg_e]\n\t"
> > -		"movdqu 80(%[src]), %[reg_f]\n\t"
> > -		"movdqu 96(%[src]), %[reg_g]\n\t"
> > -		"movdqu 112(%[src]), %[reg_h]\n\t"
> > -		"movdqu %[reg_a], (%[dst])\n\t"
> > -		"movdqu %[reg_b], 16(%[dst])\n\t"
> > -		"movdqu %[reg_c], 32(%[dst])\n\t"
> > -		"movdqu %[reg_d], 48(%[dst])\n\t"
> > -		"movdqu %[reg_e], 64(%[dst])\n\t"
> > -		"movdqu %[reg_f], 80(%[dst])\n\t"
> > -		"movdqu %[reg_g], 96(%[dst])\n\t"
> > -		"movdqu %[reg_h], 112(%[dst])\n\t"
> > -		: [reg_a] "=x" (reg_a),
> > -		  [reg_b] "=x" (reg_b),
> > -		  [reg_c] "=x" (reg_c),
> > -		  [reg_d] "=x" (reg_d),
> > -		  [reg_e] "=x" (reg_e),
> > -		  [reg_f] "=x" (reg_f),
> > -		  [reg_g] "=x" (reg_g),
> > -		  [reg_h] "=x" (reg_h)
> > -		: [src] "r" (src),
> > -		  [dst] "r"(dst)
> > -		: "memory"
> > -	);
> > +	rte_mov32((uint8_t *)dst + 0 * 32, (const uint8_t *)src + 0 * 32);
> > +	rte_mov32((uint8_t *)dst + 1 * 32, (const uint8_t *)src + 1 * 32);
> > +	rte_mov32((uint8_t *)dst + 2 * 32, (const uint8_t *)src + 2 * 32);
> > +	rte_mov32((uint8_t *)dst + 3 * 32, (const uint8_t *)src + 3 * 32);
> >  }
> >
> > -#ifdef __INTEL_COMPILER
> > -#pragma warning(enable:593)
> > -#endif
> > -
> > +/**
> > + * Copy 256 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> >  static inline void
> >  rte_mov256(uint8_t *dst, const uint8_t *src)  {
> > -	rte_mov128(dst, src);
> > -	rte_mov128(dst + 128, src + 128);
> > +	rte_mov32((uint8_t *)dst + 0 * 32, (const uint8_t *)src + 0 * 32);
> > +	rte_mov32((uint8_t *)dst + 1 * 32, (const uint8_t *)src + 1 * 32);
> > +	rte_mov32((uint8_t *)dst + 2 * 32, (const uint8_t *)src + 2 * 32);
> > +	rte_mov32((uint8_t *)dst + 3 * 32, (const uint8_t *)src + 3 * 32);
> > +	rte_mov32((uint8_t *)dst + 4 * 32, (const uint8_t *)src + 4 * 32);
> > +	rte_mov32((uint8_t *)dst + 5 * 32, (const uint8_t *)src + 5 * 32);
> > +	rte_mov32((uint8_t *)dst + 6 * 32, (const uint8_t *)src + 6 * 32);
> > +	rte_mov32((uint8_t *)dst + 7 * 32, (const uint8_t *)src + 7 * 32);
> >  }
> >
> > -#define rte_memcpy(dst, src, n)              \
> > -	({ (__builtin_constant_p(n)) ?       \
> > -	memcpy((dst), (src), (n)) :          \
> > -	rte_memcpy_func((dst), (src), (n)); })
> > +/**
> > + * Copy 64-byte blocks from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov64blocks(uint8_t *dst, const uint8_t *src, size_t n) {
> > +	__m256i ymm0, ymm1;
> > +
> > +	while (n >= 64) {
> > +		ymm0 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 0 * 32));
> > +		n -= 64;
> > +		ymm1 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 1 * 32));
> > +		src = (const uint8_t *)src + 64;
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 0 * 32),
> ymm0);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 1 * 32),
> ymm1);
> > +		dst = (uint8_t *)dst + 64;
> > +	}
> > +}
> > +
> > +/**
> > + * Copy 256-byte blocks from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov256blocks(uint8_t *dst, const uint8_t *src, size_t n) {
> > +	__m256i ymm0, ymm1, ymm2, ymm3, ymm4, ymm5, ymm6, ymm7;
> > +
> > +	while (n >= 256) {
> > +		ymm0 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 0 * 32));
> > +		n -= 256;
> > +		ymm1 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 1 * 32));
> > +		ymm2 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 2 * 32));
> > +		ymm3 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 3 * 32));
> > +		ymm4 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 4 * 32));
> > +		ymm5 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 5 * 32));
> > +		ymm6 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 6 * 32));
> > +		ymm7 = _mm256_loadu_si256((const __m256i *)((const
> uint8_t *)src + 7 * 32));
> > +		src = (const uint8_t *)src + 256;
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 0 * 32),
> ymm0);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 1 * 32),
> ymm1);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 2 * 32),
> ymm2);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 3 * 32),
> ymm3);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 4 * 32),
> ymm4);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 5 * 32),
> ymm5);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 6 * 32),
> ymm6);
> > +		_mm256_storeu_si256((__m256i *)((uint8_t *)dst + 7 * 32),
> ymm7);
> > +		dst = (uint8_t *)dst + 256;
> > +	}
> > +}
> >
> >  static inline void *
> > -rte_memcpy_func(void *dst, const void *src, size_t n)
> > +rte_memcpy(void *dst, const void *src, size_t n)
> >  {
> >  	void *ret = dst;
> > +	int dstofss;
> > +	int bits;
> >
> > -	/* We can't copy < 16 bytes using XMM registers so do it manually. */
> > +	/**
> > +	 * Copy less than 16 bytes
> > +	 */
> >  	if (n < 16) {
> >  		if (n & 0x01) {
> >  			*(uint8_t *)dst = *(const uint8_t *)src;
> > -			dst = (uint8_t *)dst + 1;
> >  			src = (const uint8_t *)src + 1;
> > +			dst = (uint8_t *)dst + 1;
> >  		}
> >  		if (n & 0x02) {
> >  			*(uint16_t *)dst = *(const uint16_t *)src;
> > -			dst = (uint16_t *)dst + 1;
> >  			src = (const uint16_t *)src + 1;
> > +			dst = (uint16_t *)dst + 1;
> >  		}
> >  		if (n & 0x04) {
> >  			*(uint32_t *)dst = *(const uint32_t *)src;
> > -			dst = (uint32_t *)dst + 1;
> >  			src = (const uint32_t *)src + 1;
> > +			dst = (uint32_t *)dst + 1;
> >  		}
> >  		if (n & 0x08) {
> >  			*(uint64_t *)dst = *(const uint64_t *)src; @@ -201,95
> +224,410 @@
> > rte_memcpy_func(void *dst, const void *src, size_t n)
> >  		return ret;
> >  	}
> >
> > -	/* Special fast cases for <= 128 bytes */
> > +	/**
> > +	 * Fast way when copy size doesn't exceed 512 bytes
> > +	 */
> >  	if (n <= 32) {
> >  		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
> >  		rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 +
> n);
> >  		return ret;
> >  	}
> > -
> >  	if (n <= 64) {
> >  		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> >  		rte_mov32((uint8_t *)dst - 32 + n, (const uint8_t *)src - 32 +
> n);
> >  		return ret;
> >  	}
> > -
> > -	if (n <= 128) {
> > -		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > -		rte_mov64((uint8_t *)dst - 64 + n, (const uint8_t *)src - 64 +
> n);
> > +	if (n <= 512) {
> > +		if (n >= 256) {
> > +			n -= 256;
> > +			rte_mov256((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 256;
> > +			dst = (uint8_t *)dst + 256;
> > +		}
> > +		if (n >= 128) {
> > +			n -= 128;
> > +			rte_mov128((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 128;
> > +			dst = (uint8_t *)dst + 128;
> > +		}
> > +		if (n >= 64) {
> > +			n -= 64;
> > +			rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 64;
> > +			dst = (uint8_t *)dst + 64;
> > +		}
> > +COPY_BLOCK_64_BACK31:
> > +		if (n > 32) {
> > +			rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +			rte_mov32((uint8_t *)dst - 32 + n, (const uint8_t
> *)src - 32 + n);
> > +			return ret;
> > +		}
> > +		if (n > 0) {
> > +			rte_mov32((uint8_t *)dst - 32 + n, (const uint8_t
> *)src - 32 + n);
> > +		}
> >  		return ret;
> >  	}
> >
> > -	/*
> > -	 * For large copies > 128 bytes. This combination of 256, 64 and 16
> byte
> > -	 * copies was found to be faster than doing 128 and 32 byte copies as
> > -	 * well.
> > +	/**
> > +	 * Make store aligned when copy size exceeds 512 bytes
> >  	 */
> > -	for ( ; n >= 256; n -= 256) {
> > -		rte_mov256((uint8_t *)dst, (const uint8_t *)src);
> > -		dst = (uint8_t *)dst + 256;
> > -		src = (const uint8_t *)src + 256;
> > +	dstofss = 32 - (int)((long long)(void *)dst & 0x1F);
> > +	n -= dstofss;
> > +	rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +	src = (const uint8_t *)src + dstofss;
> > +	dst = (uint8_t *)dst + dstofss;
> > +
> > +	/**
> > +	 * Copy 256-byte blocks.
> > +	 * Use copy block function for better instruction order control,
> > +	 * which is important when load is unaligned.
> > +	 */
> > +	rte_mov256blocks((uint8_t *)dst, (const uint8_t *)src, n);
> > +	bits = n;
> > +	n = n & 255;
> > +	bits -= n;
> > +	src = (const uint8_t *)src + bits;
> > +	dst = (uint8_t *)dst + bits;
> > +
> > +	/**
> > +	 * Copy 64-byte blocks.
> > +	 * Use copy block function for better instruction order control,
> > +	 * which is important when load is unaligned.
> > +	 */
> > +	if (n >= 64) {
> > +		rte_mov64blocks((uint8_t *)dst, (const uint8_t *)src, n);
> > +		bits = n;
> > +		n = n & 63;
> > +		bits -= n;
> > +		src = (const uint8_t *)src + bits;
> > +		dst = (uint8_t *)dst + bits;
> >  	}
> >
> > -	/*
> > -	 * We split the remaining bytes (which will be less than 256) into
> > -	 * 64byte (2^6) chunks.
> > -	 * Using incrementing integers in the case labels of a switch
> statement
> > -	 * enourages the compiler to use a jump table. To get incrementing
> > -	 * integers, we shift the 2 relevant bits to the LSB position to first
> > -	 * get decrementing integers, and then subtract.
> > +	/**
> > +	 * Copy whatever left
> >  	 */
> > -	switch (3 - (n >> 6)) {
> > -	case 0x00:
> > -		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 64;
> > -		dst = (uint8_t *)dst + 64;
> > -		src = (const uint8_t *)src + 64;      /* fallthrough */
> > -	case 0x01:
> > -		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 64;
> > -		dst = (uint8_t *)dst + 64;
> > -		src = (const uint8_t *)src + 64;      /* fallthrough */
> > -	case 0x02:
> > -		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 64;
> > -		dst = (uint8_t *)dst + 64;
> > -		src = (const uint8_t *)src + 64;      /* fallthrough */
> > -	default:
> > -		;
> > +	goto COPY_BLOCK_64_BACK31;
> > +}
> > +
> > +#else /* RTE_MACHINE_CPUFLAG_AVX2 */
> > +
> > +/**
> > + * SSE & AVX implementation below
> > + */
> > +
> > +/**
> > + * Copy 16 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov16(uint8_t *dst, const uint8_t *src) {
> > +	__m128i xmm0;
> > +
> > +	xmm0 = _mm_loadu_si128((const __m128i *)(const __m128i *)src);
> > +	_mm_storeu_si128((__m128i *)dst, xmm0); }
> > +
> > +/**
> > + * Copy 32 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov32(uint8_t *dst, const uint8_t *src) {
> > +	rte_mov16((uint8_t *)dst + 0 * 16, (const uint8_t *)src + 0 * 16);
> > +	rte_mov16((uint8_t *)dst + 1 * 16, (const uint8_t *)src + 1 * 16); }
> > +
> > +/**
> > + * Copy 64 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov64(uint8_t *dst, const uint8_t *src) {
> > +	rte_mov16((uint8_t *)dst + 0 * 16, (const uint8_t *)src + 0 * 16);
> > +	rte_mov16((uint8_t *)dst + 1 * 16, (const uint8_t *)src + 1 * 16);
> > +	rte_mov16((uint8_t *)dst + 2 * 16, (const uint8_t *)src + 2 * 16);
> > +	rte_mov16((uint8_t *)dst + 3 * 16, (const uint8_t *)src + 3 * 16); }
> > +
> > +/**
> > + * Copy 128 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov128(uint8_t *dst, const uint8_t *src) {
> > +	rte_mov16((uint8_t *)dst + 0 * 16, (const uint8_t *)src + 0 * 16);
> > +	rte_mov16((uint8_t *)dst + 1 * 16, (const uint8_t *)src + 1 * 16);
> > +	rte_mov16((uint8_t *)dst + 2 * 16, (const uint8_t *)src + 2 * 16);
> > +	rte_mov16((uint8_t *)dst + 3 * 16, (const uint8_t *)src + 3 * 16);
> > +	rte_mov16((uint8_t *)dst + 4 * 16, (const uint8_t *)src + 4 * 16);
> > +	rte_mov16((uint8_t *)dst + 5 * 16, (const uint8_t *)src + 5 * 16);
> > +	rte_mov16((uint8_t *)dst + 6 * 16, (const uint8_t *)src + 6 * 16);
> > +	rte_mov16((uint8_t *)dst + 7 * 16, (const uint8_t *)src + 7 * 16); }
> > +
> > +/**
> > + * Copy 256 bytes from one location to another,
> > + * locations should not overlap.
> > + */
> > +static inline void
> > +rte_mov256(uint8_t *dst, const uint8_t *src) {
> > +	rte_mov16((uint8_t *)dst + 0 * 16, (const uint8_t *)src + 0 * 16);
> > +	rte_mov16((uint8_t *)dst + 1 * 16, (const uint8_t *)src + 1 * 16);
> > +	rte_mov16((uint8_t *)dst + 2 * 16, (const uint8_t *)src + 2 * 16);
> > +	rte_mov16((uint8_t *)dst + 3 * 16, (const uint8_t *)src + 3 * 16);
> > +	rte_mov16((uint8_t *)dst + 4 * 16, (const uint8_t *)src + 4 * 16);
> > +	rte_mov16((uint8_t *)dst + 5 * 16, (const uint8_t *)src + 5 * 16);
> > +	rte_mov16((uint8_t *)dst + 6 * 16, (const uint8_t *)src + 6 * 16);
> > +	rte_mov16((uint8_t *)dst + 7 * 16, (const uint8_t *)src + 7 * 16);
> > +	rte_mov16((uint8_t *)dst + 8 * 16, (const uint8_t *)src + 8 * 16);
> > +	rte_mov16((uint8_t *)dst + 9 * 16, (const uint8_t *)src + 9 * 16);
> > +	rte_mov16((uint8_t *)dst + 10 * 16, (const uint8_t *)src + 10 * 16);
> > +	rte_mov16((uint8_t *)dst + 11 * 16, (const uint8_t *)src + 11 * 16);
> > +	rte_mov16((uint8_t *)dst + 12 * 16, (const uint8_t *)src + 12 * 16);
> > +	rte_mov16((uint8_t *)dst + 13 * 16, (const uint8_t *)src + 13 * 16);
> > +	rte_mov16((uint8_t *)dst + 14 * 16, (const uint8_t *)src + 14 * 16);
> > +	rte_mov16((uint8_t *)dst + 15 * 16, (const uint8_t *)src + 15 * 16);
> > +}
> > +
> > +/**
> > + * Macro for copying unaligned block from one location to another
> > +with constant load offset,
> > + * 47 bytes leftover maximum,
> > + * locations should not overlap.
> > + * Requirements:
> > + * - Store is aligned
> > + * - Load offset is <offset>, which must be immediate value within
> > +[1, 15]
> > + * - For <src>, make sure <offset> bit backwards & <16 - offset> bit
> > +forwards are available for loading
> > + * - <dst>, <src>, <len> must be variables
> > + * - __m128i <xmm0> ~ <xmm8> must be pre-defined  */
> > +#define MOVEUNALIGNED_LEFT47_IMM(dst, src, len, offset)
> \
> > +({                                                                                                          \
> > +    int tmp;                                                                                                \
> > +    while (len >= 128 + 16 - offset) {                                                                      \
> > +        xmm0 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 0 * 16));                  \
> > +        len -= 128;                                                                                         \
> > +        xmm1 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 1 * 16));                  \
> > +        xmm2 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 2 * 16));                  \
> > +        xmm3 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 3 * 16));                  \
> > +        xmm4 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 4 * 16));                  \
> > +        xmm5 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 5 * 16));                  \
> > +        xmm6 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 6 * 16));                  \
> > +        xmm7 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 7 * 16));                  \
> > +        xmm8 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 8 * 16));                  \
> > +        src = (const uint8_t *)src + 128;                                                                   \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 0 * 16),
> _mm_alignr_epi8(xmm1, xmm0, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 1 * 16),
> _mm_alignr_epi8(xmm2, xmm1, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 2 * 16),
> _mm_alignr_epi8(xmm3, xmm2, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 3 * 16),
> _mm_alignr_epi8(xmm4, xmm3, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 4 * 16),
> _mm_alignr_epi8(xmm5, xmm4, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 5 * 16),
> _mm_alignr_epi8(xmm6, xmm5, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 6 * 16),
> _mm_alignr_epi8(xmm7, xmm6, offset));        \
> > +        _mm_storeu_si128((__m128i *)((uint8_t *)dst + 7 * 16),
> _mm_alignr_epi8(xmm8, xmm7, offset));        \
> > +        dst = (uint8_t *)dst + 128;                                                                         \
> > +    }                                                                                                       \
> > +    tmp = len;                                                                                              \
> > +    len = ((len - 16 + offset) & 127) + 16 - offset;                                                        \
> > +    tmp -= len;                                                                                             \
> > +    src = (const uint8_t *)src + tmp;                                                                       \
> > +    dst = (uint8_t *)dst + tmp;                                                                             \
> > +    if (len >= 32 + 16 - offset) {                                                                          \
> > +        while (len >= 32 + 16 - offset) {                                                                   \
> > +            xmm0 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 0 * 16));              \
> > +            len -= 32;                                                                                      \
> > +            xmm1 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 1 * 16));              \
> > +            xmm2 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src -
> offset + 2 * 16));              \
> > +            src = (const uint8_t *)src + 32;                                                                \
> > +            _mm_storeu_si128((__m128i *)((uint8_t *)dst + 0 * 16),
> _mm_alignr_epi8(xmm1, xmm0, offset));    \
> > +            _mm_storeu_si128((__m128i *)((uint8_t *)dst + 1 * 16),
> _mm_alignr_epi8(xmm2, xmm1, offset));    \
> > +            dst = (uint8_t *)dst + 32;                                                                      \
> > +        }                                                                                                   \
> > +        tmp = len;                                                                                          \
> > +        len = ((len - 16 + offset) & 31) + 16 - offset;                                                     \
> > +        tmp -= len;                                                                                         \
> > +        src = (const uint8_t *)src + tmp;                                                                   \
> > +        dst = (uint8_t *)dst + tmp;                                                                         \
> > +    }                                                                                                       \
> > +})
> > +
> > +/**
> > + * Macro for copying unaligned block from one location to another,
> > + * 47 bytes leftover maximum,
> > + * locations should not overlap.
> > + * Use switch here because the aligning instruction requires immediate
> value for shift count.
> > + * Requirements:
> > + * - Store is aligned
> > + * - Load offset is <offset>, which must be within [1, 15]
> > + * - For <src>, make sure <offset> bit backwards & <16 - offset> bit
> > +forwards are available for loading
> > + * - <dst>, <src>, <len> must be variables
> > + * - __m128i <xmm0> ~ <xmm8> used in MOVEUNALIGNED_LEFT47_IMM
> must be
> > +pre-defined  */
> > +#define MOVEUNALIGNED_LEFT47(dst, src, len, offset)                   \
> > +({                                                                    \
> > +    switch (offset) {                                                 \
> > +    case 0x01: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x01); break;    \
> > +    case 0x02: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x02); break;    \
> > +    case 0x03: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x03); break;    \
> > +    case 0x04: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x04); break;    \
> > +    case 0x05: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x05); break;    \
> > +    case 0x06: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x06); break;    \
> > +    case 0x07: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x07); break;    \
> > +    case 0x08: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x08); break;    \
> > +    case 0x09: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x09); break;    \
> > +    case 0x0A: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0A); break;    \
> > +    case 0x0B: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0B); break;    \
> > +    case 0x0C: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0C); break;    \
> > +    case 0x0D: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0D); break;    \
> > +    case 0x0E: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0E); break;    \
> > +    case 0x0F: MOVEUNALIGNED_LEFT47_IMM(dst, src, n, 0x0F); break;    \
> > +    default:;                                                         \
> > +    }                                                                 \
> > +})
> 
> We probably didn't understand each other properly.
> My thought was to do something like:
> 
> #define MOVEUNALIGNED_128(offset)	do { \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 0 * 16),
> _mm_alignr_epi8(xmm1, xmm0, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 1 * 16),
> _mm_alignr_epi8(xmm2, xmm1, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 2 * 16),
> _mm_alignr_epi8(xmm3, xmm2, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 3 * 16),
> _mm_alignr_epi8(xmm4, xmm3, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 4 * 16),
> _mm_alignr_epi8(xmm5, xmm4, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 5 * 16),
> _mm_alignr_epi8(xmm6, xmm5, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 6 * 16),
> _mm_alignr_epi8(xmm7, xmm6, offset));        \
>  _mm_storeu_si128((__m128i *)((uint8_t *)dst + 7 * 16),
> _mm_alignr_epi8(xmm8, xmm7, offset));       \
> } while(0);
> 
> 
> Then at MOVEUNALIGNED_LEFT47_IMM:
> ....
> xmm7 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src - offset + 7
> * 16));                  \
> xmm8 = _mm_loadu_si128((const __m128i *)((const uint8_t *)src - offset + 8
> * 16));                  \
> src = (const uint8_t *)src + 128;
> 
> switch(offset) {
>     case 0x01: MOVEUNALIGNED_128(1); break;
>     ...
>     case 0x0f: MOVEUNALIGNED_128(f); break; } ...
> dst = (uint8_t *)dst + 128
> 
> An then in rte_memcpy() you don't need a switch for
> MOVEUNALIGNED_LEFT47_IMM itself.
> Thought it might help to generate smaller code for rte_ememcpy() while
> keeping performance reasonably high.
> 
> Konstantin
> 
> 
> > +
> > +static inline void *
> > +rte_memcpy(void *dst, const void *src, size_t n) {
> > +	__m128i xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7,
> xmm8;
> > +	void *ret = dst;
> > +	int dstofss;
> > +	int srcofs;
> > +
> > +	/**
> > +	 * Copy less than 16 bytes
> > +	 */
> > +	if (n < 16) {
> > +		if (n & 0x01) {
> > +			*(uint8_t *)dst = *(const uint8_t *)src;
> > +			src = (const uint8_t *)src + 1;
> > +			dst = (uint8_t *)dst + 1;
> > +		}
> > +		if (n & 0x02) {
> > +			*(uint16_t *)dst = *(const uint16_t *)src;
> > +			src = (const uint16_t *)src + 1;
> > +			dst = (uint16_t *)dst + 1;
> > +		}
> > +		if (n & 0x04) {
> > +			*(uint32_t *)dst = *(const uint32_t *)src;
> > +			src = (const uint32_t *)src + 1;
> > +			dst = (uint32_t *)dst + 1;
> > +		}
> > +		if (n & 0x08) {
> > +			*(uint64_t *)dst = *(const uint64_t *)src;
> > +		}
> > +		return ret;
> >  	}
> >
> > -	/*
> > -	 * We split the remaining bytes (which will be less than 64) into
> > -	 * 16byte (2^4) chunks, using the same switch structure as above.
> > +	/**
> > +	 * Fast way when copy size doesn't exceed 512 bytes
> >  	 */
> > -	switch (3 - (n >> 4)) {
> > -	case 0x00:
> > -		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 16;
> > -		dst = (uint8_t *)dst + 16;
> > -		src = (const uint8_t *)src + 16;      /* fallthrough */
> > -	case 0x01:
> > -		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 16;
> > -		dst = (uint8_t *)dst + 16;
> > -		src = (const uint8_t *)src + 16;      /* fallthrough */
> > -	case 0x02:
> > +	if (n <= 32) {
> >  		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
> > -		n -= 16;
> > -		dst = (uint8_t *)dst + 16;
> > -		src = (const uint8_t *)src + 16;      /* fallthrough */
> > -	default:
> > -		;
> > +		rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 +
> n);
> > +		return ret;
> >  	}
> > -
> > -	/* Copy any remaining bytes, without going beyond end of buffers
> */
> > -	if (n != 0) {
> > +	if (n <= 48) {
> > +		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +		rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 +
> n);
> > +		return ret;
> > +	}
> > +	if (n <= 64) {
> > +		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +		rte_mov16((uint8_t *)dst + 32, (const uint8_t *)src + 32);
> >  		rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 +
> n);
> > +		return ret;
> > +	}
> > +	if (n <= 128) {
> > +		goto COPY_BLOCK_128_BACK15;
> >  	}
> > -	return ret;
> > +	if (n <= 512) {
> > +		if (n >= 256) {
> > +			n -= 256;
> > +			rte_mov128((uint8_t *)dst, (const uint8_t *)src);
> > +			rte_mov128((uint8_t *)dst + 128, (const uint8_t *)src
> + 128);
> > +			src = (const uint8_t *)src + 256;
> > +			dst = (uint8_t *)dst + 256;
> > +		}
> > +COPY_BLOCK_255_BACK15:
> > +		if (n >= 128) {
> > +			n -= 128;
> > +			rte_mov128((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 128;
> > +			dst = (uint8_t *)dst + 128;
> > +		}
> > +COPY_BLOCK_128_BACK15:
> > +		if (n >= 64) {
> > +			n -= 64;
> > +			rte_mov64((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 64;
> > +			dst = (uint8_t *)dst + 64;
> > +		}
> > +COPY_BLOCK_64_BACK15:
> > +		if (n >= 32) {
> > +			n -= 32;
> > +			rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +			src = (const uint8_t *)src + 32;
> > +			dst = (uint8_t *)dst + 32;
> > +		}
> > +		if (n > 16) {
> > +			rte_mov16((uint8_t *)dst, (const uint8_t *)src);
> > +			rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t
> *)src - 16 + n);
> > +			return ret;
> > +		}
> > +		if (n > 0) {
> > +			rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t
> *)src - 16 + n);
> > +		}
> > +		return ret;
> > +	}
> > +
> > +	/**
> > +	 * Make store aligned when copy size exceeds 512 bytes,
> > +	 * and make sure the first 15 bytes are copied, because
> > +	 * unaligned copy functions require up to 15 bytes
> > +	 * backwards access.
> > +	 */
> > +	dstofss = 16 - (int)((long long)(void *)dst & 0x0F) + 16;
> > +	n -= dstofss;
> > +	rte_mov32((uint8_t *)dst, (const uint8_t *)src);
> > +	src = (const uint8_t *)src + dstofss;
> > +	dst = (uint8_t *)dst + dstofss;
> > +	srcofs = (int)((long long)(const void *)src & 0x0F);
> > +
> > +	/**
> > +	 * For aligned copy
> > +	 */
> > +	if (srcofs == 0) {
> > +		/**
> > +		 * Copy 256-byte blocks
> > +		 */
> > +		for (; n >= 256; n -= 256) {
> > +			rte_mov256((uint8_t *)dst, (const uint8_t *)src);
> > +			dst = (uint8_t *)dst + 256;
> > +			src = (const uint8_t *)src + 256;
> > +		}
> > +
> > +		/**
> > +		 * Copy whatever left
> > +		 */
> > +		goto COPY_BLOCK_255_BACK15;
> > +	}
> > +
> > +	/**
> > +	 * For copy with unaligned load
> > +	 */
> > +	MOVEUNALIGNED_LEFT47(dst, src, n, srcofs);
> > +
> > +	/**
> > +	 * Copy whatever left
> > +	 */
> > +	goto COPY_BLOCK_64_BACK15;
> >  }
> >
> > +#endif /* RTE_MACHINE_CPUFLAG_AVX2 */
> > +
> >  #ifdef __cplusplus
> >  }
> >  #endif
> > --
> > 1.9.3



More information about the dev mailing list