From: "Stephen C. Tweedie" <sct@redhat.com>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>,
Linus Torvalds <torvalds@transmeta.com>,
Christoph Hellwig <hch@caldera.de>, Steve Lord <lord@sgi.com>,
linux-kernel@vger.kernel.org,
kiobuf-io-devel@lists.sourceforge.net,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains
Date: Mon, 5 Feb 2001 15:03:54 +0000 [thread overview]
Message-ID: <20010205150354.E1167@redhat.com> (raw)
In-Reply-To: <20010201220744.K11607@redhat.com> <Pine.LNX.4.10.10102031224210.8867-100000@penguin.transmeta.com> <20010205110336.A1167@redhat.com> <3A7E95F3.38B26DC@colorfullife.com>
In-Reply-To: <3A7E95F3.38B26DC@colorfullife.com>; from manfred@colorfullife.com on Mon, Feb 05, 2001 at 01:00:51PM +0100
Hi,
On Mon, Feb 05, 2001 at 01:00:51PM +0100, Manfred Spraul wrote:
> "Stephen C. Tweedie" wrote:
> >
> > You simply cannot do physical disk IO on
> > non-sector-aligned memory or in chunks which aren't a multiple of
> > sector size.
>
> Why not?
>
> Obviously the disk access itself must be sector aligned and the total
> length must be a multiple of the sector length, but there shouldn't be
> any restrictions on the data buffers.
But there are. Many controllers just break down and corrupt things
silently if you don't align the data buffers (Jeff Merkey found this
by accident when he started generating unaligned IOs within page
boundaries in his NWFS code). And a lot of controllers simply cannot
break a sector dma over a page boundary (at least not without some
form of IOMMU remapping).
Yes, it's the sort of thing that you would hope should work, but in
practice it's not reliable.
Cheers,
Stephen
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next prev parent reply other threads:[~2001-02-05 15:07 UTC|newest]
Thread overview: 201+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-01 14:44 [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains bsuparna
2001-02-01 15:09 ` Christoph Hellwig
2001-02-01 16:08 ` Steve Lord
2001-02-01 16:49 ` Stephen C. Tweedie
2001-02-01 17:02 ` Christoph Hellwig
2001-02-01 17:34 ` Alan Cox
2001-02-01 17:49 ` Stephen C. Tweedie
2001-02-01 17:09 ` Chaitanya Tumuluri
2001-02-01 20:33 ` Christoph Hellwig
2001-02-01 20:56 ` Steve Lord
2001-02-01 20:59 ` Christoph Hellwig
2001-02-01 21:17 ` Steve Lord
2001-02-01 21:44 ` Stephen C. Tweedie
2001-02-01 22:07 ` Stephen C. Tweedie
2001-02-02 12:02 ` Christoph Hellwig
2001-02-05 12:19 ` Stephen C. Tweedie
2001-02-05 21:28 ` Ingo Molnar
2001-02-05 22:58 ` Stephen C. Tweedie
2001-02-05 23:06 ` Alan Cox
2001-02-05 23:16 ` Stephen C. Tweedie
2001-02-06 0:19 ` Manfred Spraul
2001-02-03 20:28 ` Linus Torvalds
2001-02-05 11:03 ` Stephen C. Tweedie
2001-02-05 12:00 ` Manfred Spraul
2001-02-05 15:03 ` Stephen C. Tweedie [this message]
2001-02-05 15:19 ` Alan Cox
2001-02-05 17:20 ` Stephen C. Tweedie
2001-02-05 17:29 ` Alan Cox
2001-02-05 18:49 ` Stephen C. Tweedie
2001-02-05 19:04 ` Alan Cox
2001-02-05 19:09 ` Linus Torvalds
2001-02-05 19:16 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Alan Cox
2001-02-05 19:28 ` Linus Torvalds
2001-02-05 20:54 ` Stephen C. Tweedie
2001-02-05 21:08 ` David Lang
2001-02-05 21:51 ` Alan Cox
2001-02-06 0:07 ` Stephen C. Tweedie
2001-02-06 17:00 ` Christoph Hellwig
2001-02-06 17:05 ` Stephen C. Tweedie
2001-02-06 17:14 ` Jens Axboe
2001-02-06 17:22 ` Christoph Hellwig
2001-02-06 18:26 ` Stephen C. Tweedie
2001-02-06 17:37 ` Ben LaHaise
2001-02-06 18:00 ` Jens Axboe
2001-02-06 18:09 ` Ben LaHaise
2001-02-06 19:35 ` Jens Axboe
2001-02-06 18:14 ` Linus Torvalds
2001-02-08 11:21 ` Andi Kleen
2001-02-08 14:11 ` Martin Dalecki
2001-02-08 17:59 ` Linus Torvalds
2001-02-06 18:18 ` Ingo Molnar
2001-02-06 18:25 ` Ben LaHaise
2001-02-06 18:35 ` Ingo Molnar
2001-02-06 18:54 ` Ben LaHaise
2001-02-06 18:58 ` Ingo Molnar
2001-02-06 19:11 ` Ben LaHaise
2001-02-06 19:32 ` Jens Axboe
2001-02-06 19:32 ` Ingo Molnar
2001-02-06 19:32 ` Linus Torvalds
2001-02-06 19:44 ` Ingo Molnar
2001-02-06 19:49 ` Ben LaHaise
2001-02-06 19:57 ` Ingo Molnar
2001-02-06 20:07 ` Jens Axboe
2001-02-06 20:25 ` Ben LaHaise
2001-02-06 20:41 ` Manfred Spraul
2001-02-06 20:50 ` Jens Axboe
2001-02-06 21:26 ` Manfred Spraul
2001-02-06 21:42 ` Linus Torvalds
2001-02-06 20:16 ` Marcelo Tosatti
2001-02-06 22:09 ` Jens Axboe
2001-02-06 22:26 ` Linus Torvalds
2001-02-06 21:13 ` Marcelo Tosatti
2001-02-06 23:26 ` Linus Torvalds
2001-02-07 23:17 ` select() returning busy for regular files [was Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait] Pavel Machek
2001-02-08 13:57 ` Ben LaHaise
2001-02-08 17:52 ` Linus Torvalds
2001-02-08 15:06 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Ben LaHaise
2001-02-08 13:44 ` Marcelo Tosatti
2001-02-08 13:45 ` Marcelo Tosatti
2001-02-07 23:15 ` Pavel Machek
2001-02-08 13:22 ` Stephen C. Tweedie
2001-02-08 12:03 ` Marcelo Tosatti
2001-02-08 15:46 ` Mikulas Patocka
2001-02-08 14:05 ` Marcelo Tosatti
2001-02-08 16:11 ` Mikulas Patocka
2001-02-08 14:44 ` Marcelo Tosatti
2001-02-08 16:57 ` Rik van Riel
2001-02-08 17:13 ` James Sutherland
2001-02-08 18:38 ` Linus Torvalds
2001-02-09 12:17 ` Martin Dalecki
2001-02-08 15:55 ` Jens Axboe
2001-02-08 18:09 ` Linus Torvalds
2001-02-08 14:52 ` Mikulas Patocka
2001-02-08 19:50 ` Stephen C. Tweedie
2001-02-11 21:30 ` Pavel Machek
2001-02-06 21:57 ` Manfred Spraul
2001-02-06 22:13 ` Linus Torvalds
2001-02-06 22:26 ` Andre Hedrick
2001-02-06 20:49 ` Jens Axboe
2001-02-07 0:21 ` Stephen C. Tweedie
2001-02-07 0:25 ` Ingo Molnar
2001-02-07 0:36 ` Stephen C. Tweedie
2001-02-07 0:50 ` Linus Torvalds
2001-02-07 1:49 ` Stephen C. Tweedie
2001-02-07 2:37 ` Linus Torvalds
2001-02-07 14:52 ` Stephen C. Tweedie
2001-02-07 19:12 ` Richard Gooch
2001-02-07 20:03 ` Stephen C. Tweedie
2001-02-07 1:51 ` Jeff V. Merkey
2001-02-07 1:01 ` Ingo Molnar
2001-02-07 1:59 ` Jeff V. Merkey
2001-02-07 1:02 ` Jens Axboe
2001-02-07 1:19 ` Linus Torvalds
2001-02-07 1:39 ` Jens Axboe
2001-02-07 1:45 ` Linus Torvalds
2001-02-07 1:55 ` Jens Axboe
2001-02-07 9:10 ` David Howells
2001-02-07 12:16 ` Stephen C. Tweedie
2001-02-07 2:00 ` Jeff V. Merkey
2001-02-07 1:06 ` Ingo Molnar
2001-02-07 1:09 ` Jens Axboe
2001-02-07 1:11 ` Ingo Molnar
2001-02-07 1:26 ` Linus Torvalds
2001-02-07 2:07 ` Jeff V. Merkey
2001-02-07 1:08 ` Jens Axboe
2001-02-07 2:08 ` Jeff V. Merkey
2001-02-07 1:42 ` Jeff V. Merkey
2001-02-07 0:42 ` Linus Torvalds
2001-02-07 0:35 ` Jens Axboe
2001-02-07 0:41 ` Linus Torvalds
2001-02-07 1:27 ` Stephen C. Tweedie
2001-02-07 1:40 ` Linus Torvalds
2001-02-12 10:07 ` Jamie Lokier
2001-02-06 20:26 ` Linus Torvalds
2001-02-06 20:25 ` Christoph Hellwig
2001-02-06 20:35 ` Ingo Molnar
2001-02-06 19:05 ` Marcelo Tosatti
2001-02-06 20:59 ` Ingo Molnar
2001-02-06 21:20 ` Steve Lord
2001-02-07 18:27 ` Christoph Hellwig
2001-02-06 20:59 ` Linus Torvalds
2001-02-07 18:26 ` Christoph Hellwig
2001-02-07 18:36 ` Linus Torvalds
2001-02-07 18:44 ` Christoph Hellwig
2001-02-08 0:34 ` Neil Brown
2001-02-06 19:46 ` Ingo Molnar
2001-02-06 20:16 ` Ben LaHaise
2001-02-06 20:22 ` Ingo Molnar
2001-02-06 19:20 ` Linus Torvalds
2001-02-06 0:31 ` Roman Zippel
2001-02-06 1:01 ` Linus Torvalds
2001-02-06 9:22 ` Roman Zippel
2001-02-06 9:30 ` Ingo Molnar
2001-02-06 1:08 ` David S. Miller
2001-02-05 22:09 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains Ingo Molnar
2001-02-05 16:56 ` Linus Torvalds
2001-02-05 17:27 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Alan Cox
2001-02-05 16:36 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains Linus Torvalds
2001-02-05 19:08 ` Stephen C. Tweedie
2001-02-01 17:49 ` Christoph Hellwig
2001-02-01 17:58 ` Alan Cox
2001-02-01 18:32 ` Rik van Riel
2001-02-01 18:59 ` yodaiken
2001-02-01 19:33 ` Stephen C. Tweedie
2001-02-01 18:51 ` bcrl
2001-02-01 16:16 ` Stephen C. Tweedie
2001-02-01 17:05 ` Christoph Hellwig
2001-02-01 17:09 ` Christoph Hellwig
2001-02-01 17:41 ` Stephen C. Tweedie
2001-02-01 18:14 ` Christoph Hellwig
2001-02-01 18:25 ` Alan Cox
2001-02-01 18:39 ` Rik van Riel
2001-02-01 18:46 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Alan Cox
2001-02-01 18:48 ` [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains Christoph Hellwig
2001-02-01 18:57 ` Alan Cox
2001-02-01 19:00 ` Christoph Hellwig
2001-02-01 19:32 ` Stephen C. Tweedie
2001-02-01 20:46 ` Christoph Hellwig
2001-02-01 21:25 ` Stephen C. Tweedie
2001-02-02 11:51 ` Christoph Hellwig
2001-02-02 14:04 ` Stephen C. Tweedie
2001-02-02 4:18 ` bcrl
2001-02-02 12:12 ` Christoph Hellwig
2001-02-01 20:04 ` Chaitanya Tumuluri
-- strict thread matches above, loose matches on Subject: below --
2001-02-06 13:50 bsuparna
2001-02-06 14:07 ` Jens Axboe
[not found] <CA2569EA.00506BBC.00@d73mta05.au.ibm.com>
2001-02-05 15:01 ` Stephen C. Tweedie
2001-02-05 14:31 bsuparna
[not found] <CA2569E9.004A4E23.00@d73mta05.au.ibm.com>
2001-02-05 12:09 ` Stephen C. Tweedie
2001-02-04 13:24 bsuparna
2001-02-02 15:31 bsuparna
2001-02-01 13:20 bsuparna
2001-02-01 7:58 bsuparna
2001-02-01 12:39 ` Stephen C. Tweedie
2001-02-01 4:55 bsuparna
2001-02-01 12:19 ` Stephen C. Tweedie
2001-02-01 16:30 ` Chaitanya Tumuluri
2001-02-01 3:59 bsuparna
[not found] <CA2569E5.004D51A7.00@d73mta05.au.ibm.com>
2001-01-31 23:32 ` Stephen C. Tweedie
2001-01-31 13:58 bsuparna
2001-01-30 14:09 bsuparna
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