Re: 2.6.23-rc1: BUG_ON in kmap_atomic_prot()

From: Linus Torvalds
Date: Tue Jul 24 2007 - 15:49:18 EST




On Tue, 24 Jul 2007, Adrian Bunk wrote:
>
> > But do we
> > care so much that it's worth inlining something like buffered_rmqueue()?
> >...
>
> Where is the problem with having buffered_rmqueue() inlined?

In this case, it was a pain to just even try to find the call chain, or
read the asm.

I would encourage lots of kernel hackers to read the assembler code gcc
generates. I suspect people being aware of code generation issues (and
writing their code with that in mind) is a *much* bigger performance
impact than gcc inlining random functions.

So maybe I'm old-fashioned and crazy, but "readability of the asm result"
actually is a worthwhile goal. Not because we care directly, but because
I'd like to encourage people to do it, due to the *indirect* benefits.

Linus
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