From: Michael Tokarev <mjt@tls.msk.ru>
To: Mark Lord <lkml@rtr.ca>
Cc: "Rogério Brito" <rbrito@ime.usp.br>, linux-kernel@vger.kernel.org
Subject: Re: Quick question about libata and hdparm
Date: Sun, 19 Apr 2009 16:44:12 +0400 [thread overview]
Message-ID: <49EB1C9C.3000105@msgid.tls.msk.ru> (raw)
In-Reply-To: <49EB1A33.7050808@rtr.ca>
Mark Lord wrote:
[]
> Nearly all of the hdparm flags work fine with libata and SATA/PATA drives.
> Among the *very few* that do not, are the -m and -d flags. -c will be
> working
> in the newest kernels, but not yet in most distro kernels.
>
> The -d flag is not permitted by libata, as the kernel prefers to completely
> dictate DMA / PIO, and it does do a rather good job of it.
Well, the kernel does a good job here in *almost* all cases.
The problematic case is when a device has some bad/unreadable
blocks/sectors. When such a place occurs on read, libata
(or whatever it is) performs several retries, each time
using "less aggressive" settings - like reducing UDMA and
PIO mode till the lowest possible PIO/33. And the device
stays in that mode until reboot, even if the problematic
sector has been relocated. So it'd be nice to be able to
reset the mode back in such cases.
/mjt
next prev parent reply other threads:[~2009-04-19 12:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-19 0:22 Quick question about libata and hdparm Rogério Brito
2009-04-19 6:31 ` Robert Hancock
2009-04-19 12:33 ` Mark Lord
2009-04-19 12:44 ` Michael Tokarev [this message]
2009-04-19 12:57 ` Jeff Garzik
2009-04-19 13:06 ` Michael Tokarev
2009-04-19 20:11 ` Rogério Brito
2009-04-19 21:27 ` Jeff Garzik
2009-04-20 17:35 ` Rogério Brito
2009-04-20 18:40 ` Alan Cox
2009-04-20 20:41 ` Rogério Brito
2009-04-20 21:16 ` Alan Cox
2009-04-20 20:31 ` Bartlomiej Zolnierkiewicz
2009-04-20 20:45 ` Rogério Brito
2009-04-20 21:19 ` Alan Cox
2009-04-20 22:57 ` Rogério Brito
2009-04-21 5:32 ` Rogério Brito
2009-04-21 12:59 ` Bartlomiej Zolnierkiewicz
2009-04-23 5:56 ` Rogério Brito
2009-04-23 21:31 ` Bartlomiej Zolnierkiewicz
2009-04-24 3:00 ` Rogério Brito
2009-05-01 9:18 ` Rogério Brito
2009-05-01 10:31 ` Alan Cox
2009-05-01 11:50 ` Rogério Brito
2009-05-01 13:16 ` Alan Cox
2009-05-01 14:19 ` Rogério Brito
2009-05-01 11:20 ` Bartlomiej Zolnierkiewicz
2009-05-11 18:34 ` Jeff Garzik
2009-04-19 20:03 ` Rogério Brito
2009-04-19 23:41 ` Mark Lord
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