Date: Thu, 20 Jan 2005 19:48:38 +0100 From: Emanuel Strobl <emanuel.strobl@gmx.net> To: freebsd-stable@freebsd.org Subject: Higher ATA-Mode -> lower speed Message-ID: <200501201948.42707.emanuel.strobl@gmx.net>
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[-- Attachment #1 --] 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=4k and doesn't increase any more even not with bs=64k. Now, when I set the mode to UDMA100 I get well over 40MB/s!!!! Can anybody confirm that for different hw? Especially people like fandino who already discussed poor ata performance on -current (~16 Oct. 04). Why does UDMA133 mode limit the transfer speed so badly? And why do I get 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 [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQBB7/0KBylq0S4AzzwRAlXlAKCLCXNUVkjXQmNWDV4Hd/kOg4dNGQCfW9LK uuUs0LRqrsuhqlS4qEseVU8= =T5QT -----END PGP SIGNATURE-----
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