Re: Implementing NVMHCI...

[Szabolcs Szakacsits]

On Tue, 14 Apr 2009, Jeff Garzik wrote:
> Avi Kivity wrote:
> > Jeff Garzik wrote:
> > > Speaking of RMW...    in one sense, we have to deal with RMW anyway.
> > > Upcoming ATA hard drives will be configured with a normal 512b sector API
> > > interface, but underlying physical sector size is 1k or 4k.
> > > 
> > > The disk performs the RMW for us, but we must be aware of physical sector
> > > size in order to determine proper alignment of on-disk data, to minimize
> > > RMW cycles.
> > > 
> > 
> > Virtualization has the same issue.  OS installers will typically setup the
> > first partition at sector 63, and that means every page-sized block access
> > will be misaligned.  Particularly bad when the guest's disk is backed on a
> > regular file.
> > 
> > Windows 2008 aligns partitions on a 1MB boundary, IIRC.
> 
> Makes a lot of sense...

Since Vista at least the first partition is 2048 sector aligned.

	Szaka

--
NTFS-3G: http://ntfs-3g.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/