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Feedback: sysctl in Linux

Forum: The Linux Kernel Hackers' Guide
Re: Question Tunable Kernel Parameters?
Keywords: kernel tuning, file handles, Bus error
Date: Thu, 15 May 1997 15:14:33 GMT
From: Jukka Santala <>

The util you're looking for is sysctl (Or a system-call by the same name). However, as far as I know this isn't quite fully implemented in Linux as of yet (I just saw it on a "wishlist" for 2.2 kernels). Certainly I haven't been able to find anything meaningful on sysctl in Linux, so perhaps that post you was referring to was abotu the *BSD's which I seem to remember use sysctl rather heavily. Ofcourse there's the option to choose whether or not to compile sysctl in to the kernel at least on 2.1.37; if anybody knows for sure if working sysctl utils can be had anywhere, drop a line.

However, on the grand scale, I don't think sysctl would do it- Linux (Ok, again, at least in 2.1.37) comes with all defaults compiled to 1024fd's, and changing that would require at least increasing _FD_SETSIZE, NR_FILE and NR_OPEN. You'd have to change these in the kernel headers and recompile everything to get any changes of it working anyway.

On the grand scale, though, I somehow doubt this is your problem - running out of file descriptors rarely results in kernel crashes.