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使用 cudaMallocHost 分配页锁定内存

用于快速 DMA 的页锁定缓冲区

使用 cudaMallocHost 分配页锁定内存 是 CoddyKit 上的免费 CUDA Academy 课时。这是第 2 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 CUDA Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 CUDA Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Meet Pinned Memory

Pinned memory is host memory the operating system promises never to move or swap out. Because its physical address is fixed, the GPU can read it directly.

Also Called Page-Locked

You will see the term page-locked used as a synonym for pinned. Both mean the same thing: pages locked in place so no swapping can ever happen.

Allocate It Right

Ask CUDA for pinned memory with cudaMallocHost. It hands back an ordinary host pointer you can read and write just like any C++ array.

float* h_data;
cudaMallocHost(&h_data, N * sizeof(float));

Use It Like Normal

The returned pointer behaves like any host buffer, so your CPU code stays unchanged. You just fill it and read it exactly as before.

for (int i = 0; i < N; ++i) h_data[i] = i * 1.0f;

No More Staging

Since the pages cannot move, the driver skips its hidden staging copy. The GPU pulls straight from your buffer, so the doubled copy disappears.

Faster Transfers

The payoff is real bandwidth. Pinned transfers often run near the link's peak speed, sometimes roughly twice as fast as the pageable version.

Free It Correctly

Pinned memory needs its own matching release. Use cudaFreeHost, never the plain free, or you risk a crash and a leak.

cudaFreeHost(h_data);

It Is Not Free Real Estate

Pinned pages cannot be swapped, so they hold real RAM hostage. Pin too much and you starve the rest of the system of usable memory.

Allocation Is Slower

Locking pages takes work, so cudaMallocHost is slower to allocate than malloc. Reuse one pinned buffer across many transfers instead of reallocating.

The Real Superpower

Beyond speed, pinned memory is the key that unlocks truly asynchronous copies. Without it, cudaMemcpyAsync cannot overlap with anything.

When to Reach for It

Pin buffers that you transfer often or that feed streams. For a one-off copy of a tiny array, plain malloc is perfectly fine. 🙂

Quick Check

You allocated a buffer with cudaMallocHost. How should you release it?

Recap

cudaMallocHost pins host pages so the GPU reads them directly, giving faster copies and enabling async overlap. Always release with cudaFreeHost. 🔒

常见问题解答

「使用 cudaMallocHost 分配页锁定内存」课时是免费的吗？

是的 — 「使用 cudaMallocHost 分配页锁定内存」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 CUDA Academy 课程的其余内容，请升级到 CoddyKit PRO。 CUDA Academy 课程共包含 4 节课。

「使用 cudaMallocHost 分配页锁定内存」这节课中我会学到什么？

用于快速 DMA 的页锁定缓冲区你通过在浏览器中直接运行的动手代码来练习 CUDA Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 CUDA Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 CUDA Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 2 节课，共 4 节。

「使用 cudaMallocHost 分配页锁定内存」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 CUDA Academy 课中编写并运行代码吗？

能。每节 CUDA Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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