tcp - 64k mtu 对 lo 的优势？

Question

我看到了this commit在 Linux 内核中并被它弄糊涂了:

loopback current mtu of 16436 bytes allows no more than 3 MSS TCP segments per frame, or 48 Kbytes. Changing mtu to 64K allows TCP stack to build large frames and significantly reduces stack overhead.

Performance boost on bulk TCP transferts can be up to 30 %, partly because we now have one ACK message for two 64KB segments, and a lower probability of hitting /proc/sys/net/ipv4/tcp_reordering default limit.

--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
static void loopback_setup(struct net_device *dev)
{
-       dev->mtu                = (16 * 1024) + 20 + 20 + 12;
+       dev->mtu                = 64 * 1024;

lo 与 TCP 传输有什么关系？它不只是一个环回地址，无论出于何种原因，您都可以在其中查看以太网流量？

Answer 1

由于这是对环回接口(interface)的更改，因此本地接口(interface)的传输性能得到提升。例如，如果您通过 FTP 连接到 127.0.0.1。