Re: atomicity
H. Peter Anvin (hpa@transmeta.com)
7 Dec 1998 19:55:43 GMT
Followup to: <m3soeszi1e.fsf@trantor.cosmic.com>
By author: Mirian Crzig Lennox <mirian@xensei.com>
In newsgroup: linux.dev.kernel
>
> alan@lxorguk.ukuu.org.uk (Alan Cox) writes:
> >
> > ext2fs tries to grab linear chunks of disk and divides the disk into cylinder
> > groups to also help to maintain locality. The BSD ffs papers [McKusik et al]
> > describe this sort of stuff well.
>
> I am astonished to hear that ext2fs uses cyl groups.
>
> I was of the impression that these were an artefact of ffs, and really
> not useful anymore. With modern disks, chances are excellent that the
> specific 3D geometry the file system sees is an utter fiction, and
> that cylinder locality is thus more-or-less a meaningless concept.
>
Actually, ext2fs uses *block groups*. It aligns them on a number of
blocks that's a power of 2 (usually 2^13 blocks); not on a "cylinder" boundary.
-hpa
--
PGP: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD 1E DF FE 69 EE 35 BD 74
See http://www.zytor.com/~hpa/ for web page and full PGP public key
I am Bahá'í -- ask me about it or see http://www.bahai.org/
"To love another person is to see the face of God." -- Les Misérables
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/