Re: sched_setaffinity usability

[Linus Torvalds]

On Thu, 18 Mar 2004, Christoph Hellwig wrote:
> 
> Like, umm, the long overdue sysconf()?  For the time beeing a sysctl might
> be the easiest thing..

"sysconf" has not been "long-overdue". It's just that glibc hasn't (after 
years of pleading) just fixed it.

sysconf() MUST NOT be done in kernel space. A lot of the sysconf() options
are pure user space stuff that the kernel has no idea about. Take a quick
look at some of those things, and realize that there are things like
"_SC_EXPR_NEST_MAX" etc that are _most_ of the values. And the kernel is
simply not involved in any of this.

So I will tell this one more time (and I bet I'll have to repeat myself
again in a year or two, and I bet I'll be ignored then too).

sysconf() is a user-level implementation issue, and so is something like
"number of CPU's". Damn, the simplest way to do it is as a environment
variable, for christ sake! Just make a magic environment variable called
__SC_ARRAY, and make it be some kind of binary encoding if you worry about
performance.

Or make a "/etc/sysconf/array" file, and just map it and look up the 
values there.

Please don't raise this issue again.

		Linus
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