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| _2025-03-11_10：07：09_ | 2025-03-11 10：07：09 | | qemu内存迁移流程_虚拟机的内存迁移可以包含哪几个阶段-CSDN博客 | | 原文链接失效了?试试备份 | | TAGs:虚拟化&容器 热迁移 | | Summary: This text is about the process of migrating memory in QEMU using libvirt. It explains that the migration process involves setting up the destination QEMU, transferring the memory, and completing the migration by copying VMState. The text also mentures that the memory transfer can be limited by bandwidth, and that the first transfer of all dirty pages may require sending all memory pages. The text also mentions that there are two types of migration: pre-copy and post-copy. Pre-copy migration involves copying all memory pages to the destination before starting it, while post-copy migration involves copying pages as they are needed after the destination is started. The text also mentions that the choice between pre-copy and post-copy migration depends on the amount of memory being transferred and the available bandwidth. The text also mentions that there are different methods for transferring memory, including using TCP, Unix domain sockets, and executables. The text also explains that libvirt typically uses the fd method for transferring memory, which involves the upper application program (libvirt) opening a file descriptor and the qemu process only writing data to it. The text also explains that the libvirt process prepares the destination socket fd and passes it to qemu, which is done through Linux inter-process communication. The text also explains that the libvirt process passes the struct file pointer to qemu, allowing it to write information to the fd after libvirt. The text also mentions that this is similar to the situation with fork and child processes, but it requires using the method of passing file descriptors instead. The text also includes a diagram showing the source and destination qemu's memory transfer process.本文介绍了使用 libvirt 迁移 QEMU 中内存的过程。它解释了迁移过程包括设置目标 QEMU、传输内存以及通过复制 VMState 完成迁移。该文本还指出，内存传输可能会受到带宽的限制，并且所有脏页的第一次传输可能需要发送所有内存页。文本还提到有两种类型的迁移：pre-copy 和 post-copy。复制前迁移涉及在启动之前将所有内存页复制到目标，而复制后迁移涉及在启动目标后根据需要复制页面。正文还提到，在复制前和复制后迁移之间进行选择取决于要传输的内存量和可用带宽。文本还提到了传输内存的不同方法，包括使用 TCP、Unix 域套接字和可执行文件。该文本还解释了 libvirt 通常使用 fd 方法来传输内存，这涉及上层应用程序 （libvirt） 打开一个文件描述符，而 qemu 进程只向其写入数据。该文本还解释了 libvirt 进程准备目标套接字 fd 并将其传递给 qemu，这是通过 Linux 进程间通信完成的。该文本还解释了 libvirt 进程将结构文件指针传递给 qemu，允许它在 libvirt 之后将信息写入 fd。文本还提到，这类似于 fork 和子进程的情况，但它需要使用传递文件描述符的方法。文本还包括一个图表，其中显示了源和目标 qemu 的内存传输过程。 | |
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