Re: 2.6.1-rc1-tiny2

[Nick Piggin <piggin@cyberone.com.au>]

Matt Mackall wrote:

>On Tue, Jan 06, 2004 at 05:33:58PM +1100, Nick Piggin wrote:
>
>>
>>Matt Mackall wrote:
>>
>>
>>>This is the fourth release of the -tiny kernel tree. The aim of this
>>>tree is to collect patches that reduce kernel disk and memory
>>>footprint as well as tools for working on small systems. Target users
>>>are things like embedded systems, small or legacy desktop folks, and
>>>handhelds.
>>>
>>>
>>Have you considered Adrian Bunk's CPU selection rationalisation work?
>>
>
>Vaguely aware of it.
>

Basically, because the types of x86 cpus are only partially ordered,
and a the CPU selection somehow tries to follow the rule "this CPU or
higher", there ends up being a bit of stuff included which doesn't
need to be. Not sure what the savings add up to though...

>
>>The last argument I heard against it was that there is lower hanging
>>fruit for size reduction. You seem to have got a lot of that.
>>
>
>Yes, a fair amount. Btw, what's the size differential for piggin-sched
>vs mainline?
>

Very little, I think my sched.o is about 40 bytes bigger on UP. Its about
4K bigger for SMP, but thats with quite a bit of init stuff to set up the
sched domains. It also does HT scheduling, and some more of that could be
ifdefed I guess (its already 1-2K smaller than Ingo's shared runqueues).

If you're talking about my interactivity stuff, then that is very little
difference as well, maybe a few tens of bytes smaller. The scheduler is
pretty lean.