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>
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--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--
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