On Thu, Aug 13, 2009 at 10:05 PM, Robert Millan<r...@aybabtu.com> wrote: > On Thu, Aug 13, 2009 at 06:04:35PM +0200, Vladimir 'phcoder' Serbinenko wrote: > > This looks a bit odd (a mask applied to an integer?), but if it's really > this way, please go ahead with it. > It's the so-called skewness. Let's say you place inodes on addresses (C/H/S) (0/0/1) and (1/0/1) you first read the metadata at (0/0/1) then you try to fetch the metadata from (0/1/1). Responding to your request harddrive moves the head to cylinder number 1 but it takes some time. Meanwhile the plates have spinned (they are spinning constantly) and perhaps head is above sector (1/0/10) and you need to wait for complete rotation to fetch your sector. If you write inodes at (0/0/1) and (1/0/15) you will need to wait only for 4 sectors. This is called skewness and was an optimisation technique in the past. But now OS doesn't know about physical geometry and so can't do such kind of optimisation. I suppose it's why it's not used anymore for UFS2. I don't know if FreeBSD variant of UFS1 still uses this feature. > Btw, your mailer marked this attachment as application/octet-stream (I can't > context-reply :-( ) > I forgot the extension. Sorry. > -- > Robert Millan > > The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and > how) you may access your data; but nobody's threatening your freedom: we > still allow you to remove your data and not access it at all." > > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > http://lists.gnu.org/mailman/listinfo/grub-devel >
-- Regards Vladimir 'phcoder' Serbinenko Personal git repository: http://repo.or.cz/w/grub2/phcoder.git _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
