Question

对setsockopt的调用似乎已成功，但使用getsockopt进行检查表明TCP_NODELAY未正确设置。

以下是我的相关部分。

我错过了什么吗？

[00007fd101b10327] socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 4
[00007fd102c6d520] connect(4, {sa_family=AF_INET, sin_port=htons(31695), sin_addr=inet_addr("[removed]")}, 16) = 0
[00007fd102c6d1e0] write(3, "110816.344860 [I.COMM_NET] TCP c"..., 155) = 155
[00007fd101a4e880] rt_sigprocmask(SIG_BLOCK, [CHLD], [PIPE], 8) = 0
[00007fd101a4e75d] rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
[00007fd101a4e880] rt_sigprocmask(SIG_SETMASK, [PIPE], NULL, 8) = 0
[00007fd101ad6470] nanosleep({1, 0}, 0x7fff66f9df40) = 0
[00007fd101b102ca] setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
[00007fd101a4e880] rt_sigprocmask(SIG_BLOCK, [CHLD], [PIPE], 8) = 0
[00007fd101a4e75d] rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
[00007fd101a4e880] rt_sigprocmask(SIG_SETMASK, [PIPE], NULL, 8) = 0
[00007fd101ad6470] nanosleep({1, 0}, 0x7fff66f9df40) = 0
[00007fd101b102ca] setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
[00007fd101a4e880] rt_sigprocmask(SIG_BLOCK, [CHLD], [PIPE], 8) = 0
[00007fd101a4e75d] rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
[00007fd101a4e880] rt_sigprocmask(SIG_SETMASK, [PIPE], NULL, 8) = 0
[00007fd101ad6470] nanosleep({1, 0}, 0x7fff66f9df40) = 0
[00007fd101b0ff8a] getsockopt(4, SOL_TCP, TCP_NODELAY, "", [0]) = 0

Answer 1

strace输出并未告诉您有关TCP_NODELAY选项值的任何信息。它告诉你的是你用响应的零长度缓冲区调用getsockopt。当缓冲区的长度为零时，内核将无法返回任何有用的信息。

在输出中[0]表示您给出的缓冲区大小。您需要指定一个缓冲区大小，该大小至少是整数的大小，以便获得有用的响应。

无法在CentOS上使用setsockopt设置TCP_NODELAY

1 个答案: