Re: CONFIG_IRQBALANCE for AMD64?

[Jeff Garzik <jgarzik@pobox.com>]

Nakajima, Jun wrote:
> Today Linux is used for various configurations, including the ones that
> substantially limit the set of user commands, libraries, etc. So we want
> to keep it.


With all due respect, "it might be an embedded box" is not normally a 
reason why we keep stuff in the kernel.  With initramfs et. al., we are 
actively moving in the opposite direction.

If this was the only reason for having kirqd in the kernel, it would be 
long gone.

The reason why kirqd hasn't been removed is simply because nobody has 
stepped up to do a apples-to-apples comparison to prove that userland 
irqbalanced has any performance advantages, or disadvantages, over 
kirqd.  From a hard-numbers perspective, compared to kirqd, the userland 
solution is still largely an unknown quantity.

irqbalanced makes a lot of sense from a flexibility and policy 
perspective, and it works on multiple arches, so it has a lot more going 
for it.

"We like it in the kernel so we don't have to ship a userland component" 
is not a valid reason.

	Jeff