Re: [PATCH] sysctl: vfs_cache_divisor

[Kyle Moffett <mrmacman_g4@mac.com>]

On Mar 23, 2007, at 20:45:21, Kyle Moffett wrote:
> On Mar 23, 2007, at 16:59:02, H. Peter Anvin wrote:
>> Randy Dunlap wrote:
>>> That makes a lot of sense to me.  It gives us finer-grained  
>>> control without having to support fixed-point data.  I've been  
>>> working on the fixed-point data patch, but I'm going to give this  
>>> method some time also, to see how it looks in code (instead of  
>>> just thinking about it).
>>
>> Well, to be specific, it actually is the same thing with different  
>> syntax (38.55 or 3855/100).
>
> /* On input: reduce num/den but retain old values for display  
> purposes */
> gcd = euclid(&inputnum, &inputden);
> num = inputnum/gcd;
> den = inputden/gcd;

Whoops, if I divide inputnum and inputden by gcd I don't need to pass  
by reference.

The trivial implementation of euclid (modulo the bogus address-of  
operations above) is of course something like this:

unsigned long euclid(unsigned long a, unsigned long b)
{
	unsigned long q, r;

	if (!a || !b)
		return 1;

	do {
		q = a / b;
		r = a % b;
		a = b;
		b = r;
	} while (r);

	return a;
}