需要“计算”根据我自己的服务器需求优化 ulimit 和 fs.file-max 值

发布于 2024-11-10 16:32:28 字数 466 浏览 4 评论 0原文

需要根据我自己的服务器需求“计算”最佳 ulimit 和 fs.file-max 值。请不要与“如何在各种 Linux 发行版中设置这些限制”问题相冲突。

我想问：

有什么好的指南可以详细解释ulimit使用的参数吗？（> 2.6 系列内核）
是否有任何好的指南来显示 fs.file-max 使用指标？

其实我可以在网上找到一些旧的参考资料： http://www.faqs.org/docs/securing/chap6sec72.html “对于我们拥有的每 4M RAM，合理的值是 256：即对于具有 128 MB RAM 的机器，将其设置为 8192 - 128/4=32 32*256=8192”

任何最新的参考都值得赞赏。

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习ぎ惯性依靠 2024-11-17 16:32:28

对于fs.file-max，我认为在几乎所有情况下你都可以不理会它。如果您正在运行某种非常繁忙的服务器并且实际上用完了文件句柄，那么您可以增加它 - 但您需要增加它的值将取决于您正在运行的服务器类型和负载就它而言。一般来说，您只需要增加它，直到您不再用完文件句柄，或者直到您意识到需要更多内存或更多系统来处理负载。通过将 file-max 降低到默认值以下来“调整”事物的收益是如此之小，以至于不值得考虑 - 我的手机在 fs-max 值为 83588 时工作正常。

顺便说一句，现代内核已经使用了根据系统内存量设置 file-max 的经验法则；来自2.6内核中的fs/file_table.c：

    /*
     * One file with associated inode and dcache is very roughly 1K.
     * Per default don't use more than 10% of our memory for files. 
     */ 

    n = (mempages * (PAGE_SIZE / 1024)) / 10;
    files_stat.max_files = max_t(unsigned long, n, NR_FILE);

而files_stat.max_files是fs.file-max的设置；最终每 1MB 的 RAM 大约需要 100 个。

ulimit 当然是关于限制用户或进程分配的资源。如果您有多个用户或其他类似情况，那么您可以决定如何划分系统资源并限制内存使用、进程数量等。有关您可以设置的限制详细信息的权威指南是setrlimit 手册页（当然还有内核源代码）。

For fs.file-max, I think in almost all cases you can just leave it alone. If you are running a very busy server of some kind and actually running out of file handles, then you can increase it -- but the value you need to increase it to will depend on exactly what kind of server you are running and what the load on it is. In general you would just need to increase it until you don't run out of file handles any more, or until you realize you need more memory or more systems to handle the load. The gain from "tuning" things by reducing file-max below the default is so minimal as to not be worth thinking about -- my phone works fine with an fs-max value of 83588.

By the way, the modern kernel already uses a rule of thumb to set file-max based on the amount of memory in the system; from fs/file_table.c in the 2.6 kernel:

    /*
     * One file with associated inode and dcache is very roughly 1K.
     * Per default don't use more than 10% of our memory for files. 
     */ 

    n = (mempages * (PAGE_SIZE / 1024)) / 10;
    files_stat.max_files = max_t(unsigned long, n, NR_FILE);

and files_stat.max_files is the setting of fs.file-max; this ends up being about 100 for every 1MB of ram.

ulimits of course are about limiting resources allocated by users or processes. If you have multiple users or another situation like that, then you can decide how you want to divide up system resources and limit memory use, number of processes, etc. The definitive guide to the details of the limits you can set is the setrlimit man page (and the kernel source, of course).

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