diff mbox series

[v3] eal/x86: improve rte_memcpy const size 16 performance

Message ID 20240405124628.47151-1-mb@smartsharesystems.com (mailing list archive)
State Superseded
Delegated to: Thomas Monjalon
Headers
Series [v3] eal/x86: improve rte_memcpy const size 16 performance |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/loongarch-compilation success Compilation OK
ci/loongarch-unit-testing success Unit Testing PASS
ci/github-robot: build success github build: passed

Commit Message

Morten Brørup April 5, 2024, 12:46 p.m. UTC 
  When the rte_memcpy() size is 16, the same 16 bytes are copied twice.
In the case where the size is known to be 16 at build tine, omit the
duplicate copy.

Reduced the amount of effectively copy-pasted code by using #ifdef
inside functions instead of outside functions.

Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
v3:
* AVX2 is a superset of AVX;
  for a block of AVX code, testing for AVX suffices. (Bruce Richardson)
* Define RTE_MEMCPY_AVX if AVX is available, to avoid copy-pasting the
  check for older GCC version. (Bruce Richardson)
v2:
* For GCC, version 11 is required for proper AVX handling;
  if older GCC version, treat AVX as SSE.
  Clang does not have this issue.
  Note: Original code always treated AVX as SSE, regardless of compiler.
* Do not add copyright. (Stephen Hemminger)
---
 lib/eal/x86/include/rte_memcpy.h | 234 ++++++++-----------------------
 1 file changed, 59 insertions(+), 175 deletions(-)

Comments

Bruce Richardson April 5, 2024, 1:17 p.m. UTC | #1 
On Fri, Apr 05, 2024 at 02:46:28PM +0200, Morten Brørup wrote:
> When the rte_memcpy() size is 16, the same 16 bytes are copied twice.
> In the case where the size is known to be 16 at build tine, omit the
> duplicate copy.
> 
> Reduced the amount of effectively copy-pasted code by using #ifdef
> inside functions instead of outside functions.
> 
> Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> v3:
> * AVX2 is a superset of AVX;
>   for a block of AVX code, testing for AVX suffices. (Bruce Richardson)
> * Define RTE_MEMCPY_AVX if AVX is available, to avoid copy-pasting the
>   check for older GCC version. (Bruce Richardson)
> v2:
> * For GCC, version 11 is required for proper AVX handling;
>   if older GCC version, treat AVX as SSE.
>   Clang does not have this issue.
>   Note: Original code always treated AVX as SSE, regardless of compiler.
> * Do not add copyright. (Stephen Hemminger)
> ---
>  lib/eal/x86/include/rte_memcpy.h | 234 ++++++++-----------------------
>  1 file changed, 59 insertions(+), 175 deletions(-)
> 
> diff --git a/lib/eal/x86/include/rte_memcpy.h b/lib/eal/x86/include/rte_memcpy.h
> index 72a92290e0..b56bc46713 100644
> --- a/lib/eal/x86/include/rte_memcpy.h
> +++ b/lib/eal/x86/include/rte_memcpy.h
> @@ -27,6 +27,11 @@ extern "C" {
>  #pragma GCC diagnostic ignored "-Wstringop-overflow"
>  #endif
>  
> +/* GCC prior to version 11 doesn't compile AVX properly, so use SSE instead. */
> +#if defined __AVX__ && !(defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION < 110000))
> +#define RTE_MEMCPY_AVX
> +#endif
> +

Strictly speaking, to have the same behaviour as before, you need to check
for AVX2 also, since the issue with GCC < 11 is for (AVX && !AVX2), i.e. if
AVX2 is supported, all compilers are fine.

My suggestion:
#ifdef __AVX2__
#define RTE_MEMCPY_AVX
#elif defined __AVX__ && !(defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION < 110000))
#define RTE_MEMCPY_AVX
#endif

You can obviously merge the two branches if you want, but I find the split
slightly easier to follow, than a mix of && and || with brackets for
precedence.

Final alternative I see, you can change defined(RTE_MEMCPY_AVX) to 
"defined(__AVX2__) || defined(RTE_MEMCPY_AVX)" each place it's used.

/Bruce
diff mbox series

Patch

diff --git a/lib/eal/x86/include/rte_memcpy.h b/lib/eal/x86/include/rte_memcpy.h
index 72a92290e0..b56bc46713 100644
--- a/lib/eal/x86/include/rte_memcpy.h
+++ b/lib/eal/x86/include/rte_memcpy.h
@@ -27,6 +27,11 @@  extern "C" {
 #pragma GCC diagnostic ignored "-Wstringop-overflow"
 #endif
 
+/* GCC prior to version 11 doesn't compile AVX properly, so use SSE instead. */
+#if defined __AVX__ && !(defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION < 110000))
+#define RTE_MEMCPY_AVX
+#endif
+
 /**
  * Copy bytes from one location to another. The locations must not overlap.
  *
@@ -91,14 +96,6 @@  rte_mov15_or_less(void *dst, const void *src, size_t n)
 	return ret;
 }
 
-#if defined __AVX512F__ && defined RTE_MEMCPY_AVX512
-
-#define ALIGNMENT_MASK 0x3F
-
-/**
- * AVX512 implementation below
- */
-
 /**
  * Copy 16 bytes from one location to another,
  * locations should not overlap.
@@ -119,10 +116,15 @@  rte_mov16(uint8_t *dst, const uint8_t *src)
 static __rte_always_inline void
 rte_mov32(uint8_t *dst, const uint8_t *src)
 {
+#if defined RTE_MEMCPY_AVX
 	__m256i ymm0;
 
 	ymm0 = _mm256_loadu_si256((const __m256i *)src);
 	_mm256_storeu_si256((__m256i *)dst, ymm0);
+#else /* SSE implementation */
+	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);
+#endif
 }
 
 /**
@@ -132,10 +134,15 @@  rte_mov32(uint8_t *dst, const uint8_t *src)
 static __rte_always_inline void
 rte_mov64(uint8_t *dst, const uint8_t *src)
 {
+#if defined __AVX512F__ && defined RTE_MEMCPY_AVX512
 	__m512i zmm0;
 
 	zmm0 = _mm512_loadu_si512((const void *)src);
 	_mm512_storeu_si512((void *)dst, zmm0);
+#else /* AVX2, AVX & SSE implementation */
+	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);
+#endif
 }
 
 /**
@@ -156,12 +163,18 @@  rte_mov128(uint8_t *dst, const uint8_t *src)
 static __rte_always_inline void
 rte_mov256(uint8_t *dst, const uint8_t *src)
 {
-	rte_mov64(dst + 0 * 64, src + 0 * 64);
-	rte_mov64(dst + 1 * 64, src + 1 * 64);
-	rte_mov64(dst + 2 * 64, src + 2 * 64);
-	rte_mov64(dst + 3 * 64, src + 3 * 64);
+	rte_mov128(dst + 0 * 128, src + 0 * 128);
+	rte_mov128(dst + 1 * 128, src + 1 * 128);
 }
 
+#if defined __AVX512F__ && defined RTE_MEMCPY_AVX512
+
+/**
+ * AVX512 implementation below
+ */
+
+#define ALIGNMENT_MASK 0x3F
+
 /**
  * Copy 128-byte blocks from one location to another,
  * locations should not overlap.
@@ -231,12 +244,22 @@  rte_memcpy_generic(void *dst, const void *src, size_t n)
 	/**
 	 * Fast way when copy size doesn't exceed 512 bytes
 	 */
+	if (__builtin_constant_p(n) && n == 32) {
+		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
+		return ret;
+	}
 	if (n <= 32) {
 		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
+		if (__builtin_constant_p(n) && n == 16)
+			return ret; /* avoid (harmless) duplicate copy */
 		rte_mov16((uint8_t *)dst - 16 + n,
 				  (const uint8_t *)src - 16 + n);
 		return ret;
 	}
+	if (__builtin_constant_p(n) && n == 64) {
+		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
+		return ret;
+	}
 	if (n <= 64) {
 		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
 		rte_mov32((uint8_t *)dst - 32 + n,
@@ -313,80 +336,13 @@  rte_memcpy_generic(void *dst, const void *src, size_t n)
 	goto COPY_BLOCK_128_BACK63;
 }
 
-#elif defined __AVX2__
-
-#define ALIGNMENT_MASK 0x1F
-
-/**
- * AVX2 implementation below
- */
-
-/**
- * Copy 16 bytes from one location to another,
- * locations should not overlap.
- */
-static __rte_always_inline void
-rte_mov16(uint8_t *dst, const uint8_t *src)
-{
-	__m128i xmm0;
-
-	xmm0 = _mm_loadu_si128((const __m128i *)(const void *)src);
-	_mm_storeu_si128((__m128i *)(void *)dst, xmm0);
-}
-
-/**
- * Copy 32 bytes from one location to another,
- * locations should not overlap.
- */
-static __rte_always_inline void
-rte_mov32(uint8_t *dst, const uint8_t *src)
-{
-	__m256i ymm0;
-
-	ymm0 = _mm256_loadu_si256((const __m256i *)(const void *)src);
-	_mm256_storeu_si256((__m256i *)(void *)dst, ymm0);
-}
+#elif defined RTE_MEMCPY_AVX
 
 /**
- * Copy 64 bytes from one location to another,
- * locations should not overlap.
+ * AVX implementation below
  */
-static __rte_always_inline void
-rte_mov64(uint8_t *dst, const uint8_t *src)
-{
-	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 __rte_always_inline void
-rte_mov128(uint8_t *dst, const uint8_t *src)
-{
-	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);
-}
 
-/**
- * Copy 256 bytes from one location to another,
- * locations should not overlap.
- */
-static __rte_always_inline void
-rte_mov256(uint8_t *dst, const uint8_t *src)
-{
-	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 ALIGNMENT_MASK 0x1F
 
 /**
  * Copy 128-byte blocks from one location to another,
@@ -437,15 +393,14 @@  rte_memcpy_generic(void *dst, const void *src, size_t n)
 	/**
 	 * Fast way when copy size doesn't exceed 256 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);
+	if (__builtin_constant_p(n) && n == 32) {
+		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
 		return ret;
 	}
-	if (n <= 48) {
+	if (n <= 32) {
 		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
-		rte_mov16((uint8_t *)dst + 16, (const uint8_t *)src + 16);
+		if (__builtin_constant_p(n) && n == 16)
+			return ret; /* avoid (harmless) duplicate copy */
 		rte_mov16((uint8_t *)dst - 16 + n,
 				(const uint8_t *)src - 16 + n);
 		return ret;
@@ -513,90 +468,11 @@  rte_memcpy_generic(void *dst, const void *src, size_t n)
 
 #else /* __AVX512F__ */
 
-#define ALIGNMENT_MASK 0x0F
-
 /**
- * SSE & AVX implementation below
+ * SSE implementation below
  */
 
-/**
- * Copy 16 bytes from one location to another,
- * locations should not overlap.
- */
-static __rte_always_inline void
-rte_mov16(uint8_t *dst, const uint8_t *src)
-{
-	__m128i xmm0;
-
-	xmm0 = _mm_loadu_si128((const __m128i *)(const void *)src);
-	_mm_storeu_si128((__m128i *)(void *)dst, xmm0);
-}
-
-/**
- * Copy 32 bytes from one location to another,
- * locations should not overlap.
- */
-static __rte_always_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 __rte_always_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 __rte_always_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);
-}
+#define ALIGNMENT_MASK 0x0F
 
 /**
  * Macro for copying unaligned block from one location to another with constant load offset,
@@ -712,17 +588,15 @@  rte_memcpy_generic(void *dst, const void *src, size_t n)
 	 */
 	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 <= 48) {
-		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
+		if (__builtin_constant_p(n) && n == 16)
+			return ret; /* avoid (harmless) duplicate copy */
 		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);
+		if (n > 48)
+			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;
 	}
@@ -828,8 +702,14 @@  rte_memcpy_aligned(void *dst, const void *src, size_t n)
 	}
 
 	/* Copy 16 <= size <= 32 bytes */
+	if (__builtin_constant_p(n) && n == 32) {
+		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
+		return ret;
+	}
 	if (n <= 32) {
 		rte_mov16((uint8_t *)dst, (const uint8_t *)src);
+		if (__builtin_constant_p(n) && n == 16)
+			return ret; /* avoid (harmless) duplicate copy */
 		rte_mov16((uint8_t *)dst - 16 + n,
 				(const uint8_t *)src - 16 + n);
 
@@ -837,6 +717,10 @@  rte_memcpy_aligned(void *dst, const void *src, size_t n)
 	}
 
 	/* Copy 32 < size <= 64 bytes */
+	if (__builtin_constant_p(n) && n == 64) {
+		rte_mov64((uint8_t *)dst, (const uint8_t *)src);
+		return ret;
+	}
 	if (n <= 64) {
 		rte_mov32((uint8_t *)dst, (const uint8_t *)src);
 		rte_mov32((uint8_t *)dst - 32 + n,