Re: CVS commit: [yamt-lazymbuf] src/sys/arch/amd64/include

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Mon, Feb 04, 2008 at 07:39:23PM +0900, YAMAMOTO Takashi wrote:
> > On Thu, Jan 24, 2008 at 12:11:42PM +0900, YAMAMOTO Takashi wrote:
> > > are you suggesting to sprinkle manual map calls instead of
> > > "automatic" one in mtod (and its equivalent in asm code)?
> > 
> > Yes, I would strongly prefer to do this in the high-level C code instead
> > of touching the assembly. If mtod does that, that's ok, but I would
> > prefer if the MD in_cksum backend does not have to deal with it.
> > 
> > Joerg
> 
> if we go that route, isn't it better to remove mbuf knowledge from
> the MD backend completely?  ie. like linux.

The MD backend only needs a very limited understanding of mbufs:
- m_len
- m_data
- m_next

Removing that would mean one function call per mbuf, possible register
savings and complications for handling misaligned / odd length mbufs.
That in turn would likely have a measurable performance effect.

Joerg