Re: [bloat] Measuring header file bloat effects on kernel buildperformance: a more than 2x slowdown ...

[Alexey Dobriyan]

On Mon, May 23, 2011 at 12:09 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
>      24594a2bfcaa: [PATCH] x86-64 merge
>
>     - Remove some unneeded prefetches.  Just two are enough to kickstart
>       the hardware prefetcher.
>
>   But despite touching prefetches explicitly, this too sloppily left the (now
>   dangling) prefetch.h include file around.

Well, developer removes include, developer risks compile breakage.

> Anway, what i tried to demonstrate with this mail how much *real* slowdown in
> the kernel build our current header file bloat is causing. We could literally
> halve our kernel build times if we fixed this!

News at 11!

Ingo, you're running x86 compile tests nonstop, you can very well make asm-x86
headers the strictest ones to make problem less problematic.

You (x86 merge people), removed header guards from quite a lot of asm-x86/*.h
files breaking gcc "do not open(2) second time" heuristics. It became better
since last I've noticed it, but maybe start with that?
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