Re: [PATCH 08/24] net, diet: Make TCP metrics optional

Pavel Machek
2014-06-14T20:33:54Z

On Tue 2014-05-06 11:33:11, Cong Wang wrote:
> On Tue, May 6, 2014 at 10:55 AM, <josh@joshtriplett.org> wrote:
> > On Tue, May 06, 2014 at 01:16:43PM -0400, David Miller wrote:
> >> From: josh@joshtriplett.org
> >> Date: Tue, 6 May 2014 09:41:08 -0700
> >>
> >> > Every KB of RAM costs real money and SoC die area (for eDRAM/eSRAM).
> >>
> >> Another poster commented that 16MB of DRAM would be cheaper than
> >> the 2MB of ram you have on these boards, probably one that fits
> >> your size profile is available as well.
> >>
> >> 2MB is just a rediculous restriction.
> >
> > Embedded systems experts disagree with you there; there *are* systems
> > where the most cost-efficient approach is a few MB (or a few hundred KB)
> > of non-discrete memory. We're not talking about socketed memory or even
> > soldered-down memory; we're talking about entire systems that fit on a
> > small SoC die. The space not used by that extra RAM may well be better
> > spent on CPU optimizations, or some other integrated component.
> >
> > Such boards will be built, and many of them will run Linux, despite your
> > incredulity. When you're building millions of a board, it's well worth
> > optimizing software to eliminate components from the bill of materials.
>
> So why bothers 3.15+ Linux kernel? Why not use an old kernel e.g. 2.4.x?
> 2.4.x kernel doesn't have so many new features you want to get rid of here.

So.. what is kernel composed of? Ton of drivers and a bit of generic code.

And when doing this, you probably need the drivers from 3.x for your hardware.

--
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