Skip site navigation (1)Skip section navigation (2)
Date:      Mon, 9 Jan 2012 00:27:20 +0200
From:      Kostik Belousov <kostikbel@gmail.com>
To:        Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc:        current@freebsd.org
Subject:   Re: CD9660/md(4)/UFS22 silly behaviour
Message-ID:  <20120108222720.GN31224@deviant.kiev.zoral.com.ua>
In-Reply-To: <8334.1326061310@critter.freebsd.dk>
References:  <8334.1326061310@critter.freebsd.dk>

next in thread | previous in thread | raw e-mail | index | archive | help

--JMMA/5w7oqUUivCa
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Sun, Jan 08, 2012 at 10:21:50PM +0000, Poul-Henning Kamp wrote:
>=20
> I'm doing som data-mining on a pile of ISO images right now.
>=20
> I stuck the ISOs on a UFS2 on a flash-disk for speed, and mdconfig(8)'d
> them so I could mount them.
>=20
> The traffic pattern his "interesting":
>=20
> dT: 1.003s  w: 1.000s
>  L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w   %busy Name
> [...]
>     1    733    733   1466    1.3      0      0    0.0   98.2| md39
>     1    733    733  23449    1.3      0      0    0.0   93.2| da0
>=20
> Notice the 1:16 ratio on kBps but 1:1 ratio on ops/s ?
>=20
> da0's UFS2 has 32k block-size:
>=20
> 	magic   19540119 (UFS2) time    Wed Jan  4 16:41:47 2012
> 	superblock location     65536   id      [ 4f046cf5 c30697ee ]
> 	ncg     104     size    19537685        blocks  19228156
> 	bsize   32768   shift   15      mask    0xffff8000
> 	fsize   4096    shift   12      mask    0xfffff000
> 	[...]
>=20
> It looks like every 2k read from CD9660 turns into a 32k block
> read in the UFS filesystem, without any beneficial caching happening.
>=20
> Less than optimal I'd say...
>=20
What is the access patern ? Is it random access, or sequential read
(from the cd9660 POV) ?

--JMMA/5w7oqUUivCa
Content-Type: application/pgp-signature
Content-Disposition: inline

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (FreeBSD)

iEYEARECAAYFAk8KGEgACgkQC3+MBN1Mb4jruQCcCzy7Ple7akRe/HtI+bfw/TnC
nksAniu/bgOQg5rDZS0+6wbTKBqDrA3m
=0mal
-----END PGP SIGNATURE-----

--JMMA/5w7oqUUivCa--



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20120108222720.GN31224>