shmget 大小限制问题 [英] shmget size limit issue

问题描述

我有这段代码:

if ((shmid = shmget(key, 512, IPC_CREAT | 0666)) < 0)
{   
    perror("shmget");
    exit(1);
}   

每当我将数字设置为高于 2048 时，就会出现一个错误消息:

Whenever I set the number any higher than 2048, I get, an error that says:

shmget: Invalid argument

但是，当我运行 cat/proc/sys/kernel/shmall 时，我得到 4294967296.

However when I run cat /proc/sys/kernel/shmall, I get 4294967296.

有人知道为什么会这样吗?提前致谢！

Does anybody know why this is happening? Thanks in advance!

推荐答案

Jerry 的评论是正确的，即使你没有玩过这些东西也很神秘:这个怎么样:EINVAL: ...存在具有给定键的段，但大小大于该段的大小."

The comment from Jerry is correct, even if cryptic if you haven't played with this stuff: "What about this: EINVAL: ... a segment with given key existed, but size is greater than the size of that segment."

他的意思是该段已经存在 - 这些段是持久的 - 它的大小为 2048.

He meant that the segment is already there - these segment are persistent - and it has size 2048.

您可以通过以下方式看到它:

You can see it among the other ones with:

$ ipcs -m

并且您可以通过以下方式删除您的细分受众群(注意:仅删除您的细分受众群):

and you can remove your segment (beware: remove your one only) with:

$ ipcrm -M <key>

之后，您应该可以将其创建得更大.

After that you should be able to create it larger.

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