valarray上的内存对齐

问题描述

如何在大数据块上强制使用内存分配?还是发生在您身上.

特别是在valarray上，我是否保证从0th索引获得最佳性能?

还可以检查最佳对齐方式吗?

例如，假设系统的内存按32位块对齐(这意味着，当CPU请求内存地址时，即使请求了一个字节，CPU也会获得整个32位块，而不仅仅是一个字节).
并且我定义了valarray[unsinged char] alignedArray，那么通过alignmentArray [3]对alignmentArray [0]的访问不应对内存进行多次调用(应驻留在寄存器中).

总结一下，我有2个问题. 如何(以编程方式)检查内存对齐方式，并且如何确保0索引(或至少一个已知索引)位于单词的开头?

How do you force memory alginment on a large data chunk? Or does it happen for you.

Specifically on valarray am I guranteed optimal performance from the 0th index?

Also is there a way to check what the best alignment is?

For example, assumming the memory of the system is aligned in 32 bit chunks (meaning when the CPU requests a memory address it gets the whole 32 bit chunk not just a byte even if a byte was requested)
and I have a valarray[unsinged char] alignedArray defined then the access to alignedArray[0] thru alignedArray[3] should not make more than one call into memory (should reside in the registers still).

To resummarize I have 2 questions. How do you check the memory alignment (programatically) and how do you ensure your 0 index (or atleast a known index) is at the start of the word?

推荐答案

bool TestWordBoundary(void* pTest)
{
  INT_PTR pointer = (INT_PTR) pTest;
  return (0 == pointer % sizeof(WORD));
}

void Yours()
{
  const char* szBufferTest("content");
  ASSERT(TestWordBoundary(&szBufferTest[0]));
  ASSERT(!TestWordBoundary(&szBufferTest[1]));
}

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