Date: Thu, 20 Jan 2005 20:09:57 +0100 From: Emanuel Strobl <emanuel.strobl@gmx.net> To: freebsd-stable@freebsd.org Subject: Re: Higher ATA-Mode -> lower speed Message-ID: <200501202010.01675.emanuel.strobl@gmx.net> In-Reply-To: <200501202000.43688.emanuel.strobl@gmx.net> References: <200501201948.42707.emanuel.strobl@gmx.net> <200501202000.43688.emanuel.strobl@gmx.net>
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--nextPart1618033.AHgYaLUpV2 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Am Donnerstag, 20. Januar 2005 20:00 schrieb Emanuel Strobl: > Am Donnerstag, 20. Januar 2005 19:48 schrieb Emanuel Strobl: > > Dear ata interested guys, > > > > I observed a strange behaviour which seems to explain my often noticed > > "16MB/s hard-limit" > > > > I have a UDMA133 drive (MAXTOR 6L060J3) which saturates at 16MB/s when I > > dump anything to it, regardless of the block size. This transfer rate is > > reached with bs=3D4k and doesn't increase any more even not with bs=3D6= 4k. > > > > Now, when I set the mode to UDMA100 I get well over 40MB/s!!!! > > > > Can anybody confirm that for different hw? Especially people like fandi= no > > who already discussed poor ata performance on -current (~16 Oct. 04). > > I can confirm that for my workstation here. i815 chipset and seagate > ST380011A. > When set to UDMA100 (the maximum) the following dump gives 16MB/s 'dd > if=3D/dev/zero of=3D/usr/testfile bs=3D16k count=3D2000). > When I limit the mode to UDMA66 I get 53MB/s !!!!!!!!!!!!!!!! Sorry, that's not 100% correct. After booting the machine I get 16MB/s. That's the hard limit. The disk is shown to operate with UDMA100 (that's the highest mode of the=20 chipset). Now when I issue a 'atacontrol mode 0 udma100 udma100' (set the same mode a= s=20 it's said to be) I get 57MB/s!!!!! =46rom this point it doesn't matter what mode I set, the 16MB/s hard-limit= =20 vanished :)) But the original described problem of the 16MB/s hard-limit with udma133 is= =20 reproducable, means if I return mode to udma133 I see the 16MB/s limit agai= n! =2DHarry > > It seems that's independent of UDMA133 instead it's when mode is set to t= he > maximum the chipset can handle! > > This really hurts! But it's _the_ eplanation for all the "poor ata > performance" reports. > > -Harry > > > Why does UDMA133 mode limit the transfer speed so badly? And why do I g= et > > significantly slower transfer rates (32MB/s insted of 42MB/s) when I set > > the mode to UDMA66 (compared to UDMA100 but twice the speed of UDMA133)? > > There's only one device on the channel, so UDMA66 should be fine for > > 42MB/s. The controller is a HPT372. > > > > Best regards, > > > > -Harry --nextPart1618033.AHgYaLUpV2 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQBB8AIJBylq0S4AzzwRAnOfAJwJ7zZcrzXVWXTGURfARQUVwBleowCfYS+U +eQ2vQo2MJPjrJPvXSdyYKU= =piaG -----END PGP SIGNATURE----- --nextPart1618033.AHgYaLUpV2--
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