x86/xor: Add alternative SSE implementation only prefetching once per 64-byte line
On CPUs with 64-byte last level cache lines, this yields roughly
10% better performance, independent of CPU vendor or specific
model (as far as I was able to test).
Signed-off-by: Jan Beulich <[email protected]>
Acked-by: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
diff --git a/arch/x86/include/asm/xor.h b/arch/x86/include/asm/xor.h
index c661571..d882975 100644
--- a/arch/x86/include/asm/xor.h
+++ b/arch/x86/include/asm/xor.h
@@ -58,6 +58,14 @@
#define XO2(x, y) " xorps "OFFS(x)"(%[p3]), %%xmm"#y" ;\n"
#define XO3(x, y) " xorps "OFFS(x)"(%[p4]), %%xmm"#y" ;\n"
#define XO4(x, y) " xorps "OFFS(x)"(%[p5]), %%xmm"#y" ;\n"
+#define NOP(x)
+
+#define BLK64(pf, op, i) \
+ pf(i) \
+ op(i, 0) \
+ op(i + 1, 1) \
+ op(i + 2, 2) \
+ op(i + 3, 3)
static void
xor_sse_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
@@ -111,6 +119,40 @@
}
static void
+xor_sse_2_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+{
+ unsigned long lines = bytes >> 8;
+
+ kernel_fpu_begin();
+
+ asm volatile(
+#undef BLOCK
+#define BLOCK(i) \
+ BLK64(PF0, LD, i) \
+ BLK64(PF1, XO1, i) \
+ BLK64(NOP, ST, i) \
+
+ " .align 32 ;\n"
+ " 1: ;\n"
+
+ BLOCK(0)
+ BLOCK(4)
+ BLOCK(8)
+ BLOCK(12)
+
+ " add %[inc], %[p1] ;\n"
+ " add %[inc], %[p2] ;\n"
+ " dec %[cnt] ;\n"
+ " jnz 1b ;\n"
+ : [cnt] "+r" (lines),
+ [p1] "+r" (p1), [p2] "+r" (p2)
+ : [inc] XOR_CONSTANT_CONSTRAINT (256UL)
+ : "memory");
+
+ kernel_fpu_end();
+}
+
+static void
xor_sse_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3)
{
@@ -170,6 +212,43 @@
}
static void
+xor_sse_3_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
+ unsigned long *p3)
+{
+ unsigned long lines = bytes >> 8;
+
+ kernel_fpu_begin();
+
+ asm volatile(
+#undef BLOCK
+#define BLOCK(i) \
+ BLK64(PF0, LD, i) \
+ BLK64(PF1, XO1, i) \
+ BLK64(PF2, XO2, i) \
+ BLK64(NOP, ST, i) \
+
+ " .align 32 ;\n"
+ " 1: ;\n"
+
+ BLOCK(0)
+ BLOCK(4)
+ BLOCK(8)
+ BLOCK(12)
+
+ " add %[inc], %[p1] ;\n"
+ " add %[inc], %[p2] ;\n"
+ " add %[inc], %[p3] ;\n"
+ " dec %[cnt] ;\n"
+ " jnz 1b ;\n"
+ : [cnt] "+r" (lines),
+ [p1] "+r" (p1), [p2] "+r" (p2), [p3] "+r" (p3)
+ : [inc] XOR_CONSTANT_CONSTRAINT (256UL)
+ : "memory");
+
+ kernel_fpu_end();
+}
+
+static void
xor_sse_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3, unsigned long *p4)
{
@@ -236,6 +315,45 @@
}
static void
+xor_sse_4_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
+ unsigned long *p3, unsigned long *p4)
+{
+ unsigned long lines = bytes >> 8;
+
+ kernel_fpu_begin();
+
+ asm volatile(
+#undef BLOCK
+#define BLOCK(i) \
+ BLK64(PF0, LD, i) \
+ BLK64(PF1, XO1, i) \
+ BLK64(PF2, XO2, i) \
+ BLK64(PF3, XO3, i) \
+ BLK64(NOP, ST, i) \
+
+ " .align 32 ;\n"
+ " 1: ;\n"
+
+ BLOCK(0)
+ BLOCK(4)
+ BLOCK(8)
+ BLOCK(12)
+
+ " add %[inc], %[p1] ;\n"
+ " add %[inc], %[p2] ;\n"
+ " add %[inc], %[p3] ;\n"
+ " add %[inc], %[p4] ;\n"
+ " dec %[cnt] ;\n"
+ " jnz 1b ;\n"
+ : [cnt] "+r" (lines), [p1] "+r" (p1),
+ [p2] "+r" (p2), [p3] "+r" (p3), [p4] "+r" (p4)
+ : [inc] XOR_CONSTANT_CONSTRAINT (256UL)
+ : "memory");
+
+ kernel_fpu_end();
+}
+
+static void
xor_sse_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3, unsigned long *p4, unsigned long *p5)
{
@@ -308,12 +426,63 @@
kernel_fpu_end();
}
+static void
+xor_sse_5_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
+ unsigned long *p3, unsigned long *p4, unsigned long *p5)
+{
+ unsigned long lines = bytes >> 8;
+
+ kernel_fpu_begin();
+
+ asm volatile(
+#undef BLOCK
+#define BLOCK(i) \
+ BLK64(PF0, LD, i) \
+ BLK64(PF1, XO1, i) \
+ BLK64(PF2, XO2, i) \
+ BLK64(PF3, XO3, i) \
+ BLK64(PF4, XO4, i) \
+ BLK64(NOP, ST, i) \
+
+ " .align 32 ;\n"
+ " 1: ;\n"
+
+ BLOCK(0)
+ BLOCK(4)
+ BLOCK(8)
+ BLOCK(12)
+
+ " add %[inc], %[p1] ;\n"
+ " add %[inc], %[p2] ;\n"
+ " add %[inc], %[p3] ;\n"
+ " add %[inc], %[p4] ;\n"
+ " add %[inc], %[p5] ;\n"
+ " dec %[cnt] ;\n"
+ " jnz 1b ;\n"
+ : [cnt] "+r" (lines), [p1] "+r" (p1), [p2] "+r" (p2),
+ [p3] "+r" (p3), [p4] "+r" (p4), [p5] "+r" (p5)
+ : [inc] XOR_CONSTANT_CONSTRAINT (256UL)
+ : "memory");
+
+ kernel_fpu_end();
+}
+
+static struct xor_block_template xor_block_sse_pf64 = {
+ .name = "prefetch64-sse",
+ .do_2 = xor_sse_2_pf64,
+ .do_3 = xor_sse_3_pf64,
+ .do_4 = xor_sse_4_pf64,
+ .do_5 = xor_sse_5_pf64,
+};
+
#undef LD
#undef XO1
#undef XO2
#undef XO3
#undef XO4
#undef ST
+#undef NOP
+#undef BLK64
#undef BLOCK
#undef XOR_CONSTANT_CONSTRAINT
@@ -324,4 +493,7 @@
# include <asm/xor_64.h>
#endif
+#define XOR_SELECT_TEMPLATE(FASTEST) \
+ AVX_SELECT(FASTEST)
+
#endif /* _ASM_X86_XOR_H */
diff --git a/arch/x86/include/asm/xor_32.h b/arch/x86/include/asm/xor_32.h
index b85dc87..ce05722 100644
--- a/arch/x86/include/asm/xor_32.h
+++ b/arch/x86/include/asm/xor_32.h
@@ -543,26 +543,25 @@
/* Also try the generic routines. */
#include <asm-generic/xor.h>
-#undef XOR_TRY_TEMPLATES
-#define XOR_TRY_TEMPLATES \
-do { \
- xor_speed(&xor_block_8regs); \
- xor_speed(&xor_block_8regs_p); \
- xor_speed(&xor_block_32regs); \
- xor_speed(&xor_block_32regs_p); \
- AVX_XOR_SPEED; \
- if (cpu_has_xmm) \
- xor_speed(&xor_block_pIII_sse); \
- if (cpu_has_mmx) { \
- xor_speed(&xor_block_pII_mmx); \
- xor_speed(&xor_block_p5_mmx); \
- } \
-} while (0)
-
/* We force the use of the SSE xor block because it can write around L2.
We may also be able to load into the L1 only depending on how the cpu
deals with a load to a line that is being prefetched. */
-#define XOR_SELECT_TEMPLATE(FASTEST) \
- AVX_SELECT(cpu_has_xmm ? &xor_block_pIII_sse : FASTEST)
+#undef XOR_TRY_TEMPLATES
+#define XOR_TRY_TEMPLATES \
+do { \
+ AVX_XOR_SPEED; \
+ if (cpu_has_xmm) { \
+ xor_speed(&xor_block_pIII_sse); \
+ xor_speed(&xor_block_sse_pf64); \
+ } else if (cpu_has_mmx) { \
+ xor_speed(&xor_block_pII_mmx); \
+ xor_speed(&xor_block_p5_mmx); \
+ } else { \
+ xor_speed(&xor_block_8regs); \
+ xor_speed(&xor_block_8regs_p); \
+ xor_speed(&xor_block_32regs); \
+ xor_speed(&xor_block_32regs_p); \
+ } \
+} while (0)
#endif /* _ASM_X86_XOR_32_H */
diff --git a/arch/x86/include/asm/xor_64.h b/arch/x86/include/asm/xor_64.h
index 1baf89d..546f1e3 100644
--- a/arch/x86/include/asm/xor_64.h
+++ b/arch/x86/include/asm/xor_64.h
@@ -13,17 +13,15 @@
/* Also try the AVX routines */
#include <asm/xor_avx.h>
+/* We force the use of the SSE xor block because it can write around L2.
+ We may also be able to load into the L1 only depending on how the cpu
+ deals with a load to a line that is being prefetched. */
#undef XOR_TRY_TEMPLATES
#define XOR_TRY_TEMPLATES \
do { \
AVX_XOR_SPEED; \
+ xor_speed(&xor_block_sse_pf64); \
xor_speed(&xor_block_sse); \
} while (0)
-/* We force the use of the SSE xor block because it can write around L2.
- We may also be able to load into the L1 only depending on how the cpu
- deals with a load to a line that is being prefetched. */
-#define XOR_SELECT_TEMPLATE(FASTEST) \
- AVX_SELECT(&xor_block_sse)
-
#endif /* _ASM_X86_XOR_64_H */
