用于检查有关CPU，内存，网络，NAT表使用情况的信息的API

Question

I am developing an embedded Linux system (2.6 kernel and uclibc) and I need to check for cpu, memory, network, NAT Table usage, etc...

Which API should I use? Where can i check it? I have visited some websites about the Linux kernel API but didnt find any direct information about. Any suggestion or recommendation?

My program is written in C with uclibc and gcc 3.4.6

Thanks

Answer 1

All the information you're after (and much, much more) is available in procfs:

• CPU: /proc/uptime , /proc/stat
• Memory: /proc/meminfo
• Network: /proc/net/dev
• NAT: /proc/net/ip_conntrack

As an aside: GCC 3.4.6 is reeealllly old. The oldest currently maintained version is 4.4; I'd recommend upgrading if possible. Buildroot will automate a lot of the process for you.

Answer 2

the proc file system is fairly optimal: it is a virtual file system, where all of the contents are actually created upon a read. So if noone reads info, it isn't generated.

The beauty of a text file-based interface is that it is both human readable and machine readable at the same time. Secondly, there are no endianess issues and things like that - it works better across architectures. Compared to running ioctls, which was done for a few subsystems including V4L and ALSA, it has the beauty that it is also compiler (eg #pragma pack) and ABI independent - ask ARM developers about the OABI to EABI change if you enjoy horror stories...

Note that the contents of procfs and sysfs are considered part of the stable kernel interfaces, no developer is allowed to change anything at random.