Intel ARCHITECTURE IA-32 User Manual

Optimizing Cache Usage 6
6-49
In Example 6-11, eight _mm_load_ps and _mm_stream_ps intrinsics are
used so that all of the data prefetched (a 128-byte cache line) is written
back. The prefetch and streaming-stores are executed in separate loops
to minimize the number of transitions between reading and writing data.
This significantly improves the bandwidth of the memory accesses.
// copy 128 byte per loop
for (j=kk; j<kk+NUMPERPAGE; j+=16) {
_mm_stream_ps((float*)&b[j],
_mm_load_ps((float*)&a[j]));
_mm_stream_ps((float*)&b[j+2],
_mm_load_ps((float*)&a[j+2]));
_mm_stream_ps((float*)&b[j+4],
_mm_load_ps((float*)&a[j+4]));
_mm_stream_ps((float*)&b[j+6],
_mm_load_ps((float*)&a[j+6]));
_mm_stream_ps((float*)&b[j+8],
_mm_load_ps((float*)&a[j+8]));
_mm_stream_ps((float*)&b[j+10],
_mm_load_ps((float*)&a[j+10]));
_mm_stream_ps((float*)&b[j+12],
_mm_load_ps((float*)&a[j+12]));
_mm_stream_ps((float*)&b[j+14],
_mm_load_ps((float*)&a[j+14]));
} // finished copying one block
} // finished copying N elements
_mm_sfence();
Example 6-11 A Memory Copy Routine Using Software Prefetch

Intel ARCHITECTURE IA-32 Specifications

General

Instruction Set	x86
Instruction Set Type	CISC
Memory Segmentation	Supported
Operating Modes	Real mode, Protected mode, Virtual 8086 mode
Max Physical Address Size	36 bits (with PAE)
Max Virtual Address Size	32 bits
Architecture	IA-32 (Intel Architecture 32-bit)
Addressable Memory	4 GB (with Physical Address Extension up to 64 GB)
Floating Point Registers	8 x 80-bit
MMX Registers	8 x 64-bit
SSE Registers	8 x 128-bit
Registers	General-purpose registers (EAX, EBX, ECX, EDX, ESI, EDI, ESP, EBP), Segment registers (CS, DS, SS, ES, FS, GS), Instruction pointer (EIP), Flags register (EFLAGS)
Floating Point Unit	Yes (x87)