From: Andrew Morton <akpm@osdl.org>
To: Mathieu Fluhr <mfluhr@nero.com>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: 2.6.13 brings buffer underruns when recording DVDs in 16x (was Re: "Read my lips: no more merges" - aka Linux 2.6.14-rc1)
Date: Wed, 14 Sep 2005 01:30:53 -0700 [thread overview]
Message-ID: <20050914013053.0c2b302c.akpm@osdl.org> (raw)
In-Reply-To: <1126685479.2010.14.camel@localhost.localdomain>
Mathieu Fluhr <mfluhr@nero.com> wrote:
>
> According to the MMC documentation, you can thoeriticaly send at most
> 65535 (16 bits int) blocks in one WRITE(10) CDB. This would means
> sending a buffer of ~127 MB on case of writing a mode 1 data track (2048
> bytes per block)...
>
> Now, practically, it is really not safe to send more than 64 KB per CDB
> (Mostly device related). And with such values, you have the following:
> - at 100 Hz -> 64 KB * 100 = 6400 KB/s <=> ~4.62x DVD
> - at 250 Hz -> 64 KB * 250 = 16000 KB/s <=> ~11.55x DVD
> - at 1000 Hz -> 64 KB * 1000 = 64000 KB/s <=> ~46.20x DVD
But that implies that there's some piece of code somewhere (could be
userspace, could be kernel) which is doing a timer-based sleep() in between
each CDB. It shouldn't do that - it should be using the disk
controller's completion interrupt for synchronisation.
What userspace application are you using to write the DVDs, and is it
possible to test a different one?
next prev parent reply other threads:[~2005-09-14 8:31 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-13 3:34 "Read my lips: no more merges" - aka Linux 2.6.14-rc1 Linus Torvalds
2005-09-13 3:54 ` Alejandro Bonilla Beeche
2005-09-13 3:59 ` Keith Owens
2005-09-13 4:03 ` Alejandro Bonilla Beeche
2005-09-14 5:16 ` Alejandro Bonilla Beeche
2005-09-14 16:28 ` Jeff Garzik
2005-09-14 16:40 ` Alejandro Bonilla
2005-09-14 16:43 ` Linus Torvalds
2005-09-14 16:52 ` Alejandro Bonilla
2005-09-15 0:48 ` Alejandro Bonilla Beeche
2005-09-13 14:27 ` Linus Torvalds
2005-09-13 6:28 ` more fallout from ATI Xpress timer workaround (was: Linux 2.6.14-rc1) Cal Peake
2005-09-13 20:04 ` Jean Delvare
2005-09-13 6:33 ` "Read my lips: no more merges" - aka Linux 2.6.14-rc1 Sonny Rao
2005-09-13 7:04 ` Eric Dumazet
2005-09-15 4:06 ` David S. Miller
2005-09-15 4:22 ` Linus Torvalds
2005-09-15 20:13 ` Benjamin LaHaise
2005-09-15 20:32 ` Linus Torvalds
2005-09-15 21:08 ` Eric Dumazet
2005-09-15 20:41 ` Eric Dumazet
2005-09-13 7:34 ` Udo A. Steinberg
2005-09-13 10:40 ` Mathieu Fluhr
2005-09-13 11:15 ` Helge Hafting
2005-09-13 15:14 ` Linus Torvalds
2005-09-13 17:01 ` Mathieu Fluhr
2005-09-13 17:15 ` Linus Torvalds
2005-09-13 18:12 ` Mathieu Fluhr
2005-09-13 19:11 ` Linus Torvalds
2005-09-14 8:11 ` 2.6.13 brings buffer underruns when recording DVDs in 16x (was Re: "Read my lips: no more merges" - aka Linux 2.6.14-rc1) Mathieu Fluhr
2005-09-14 8:30 ` Andrew Morton [this message]
2005-09-14 10:32 ` Mathieu Fluhr
2005-09-14 10:58 ` Andrew Morton
2005-09-14 11:12 ` Alessandro Suardi
2005-09-14 15:04 ` "Read my lips: no more merges" - aka Linux 2.6.14-rc1 Bill Davidsen
2005-09-14 23:38 ` Redeeman
2005-09-13 18:34 ` Roland Dreier
2005-09-13 18:46 ` Linus Torvalds
2005-09-13 21:32 ` Horst von Brand
2005-09-13 19:57 ` Rafael J. Wysocki
2005-09-14 15:31 ` Bill Davidsen
2005-09-14 22:56 ` Matthew Garrett
2005-09-14 17:33 ` Bill Davidsen
2005-09-14 17:45 ` Bill Davidsen
2005-09-14 21:47 ` Henrik Persson
2005-09-14 23:20 ` Jesper Juhl
2005-09-16 19:51 ` Henrik Persson
2005-09-14 22:11 ` 2.6.14-rc1 on ATI hangs when executing _STA and _INI methods Peter Osterlund
2005-09-14 22:27 ` Linus Torvalds
2005-09-14 22:41 ` Peter Osterlund
2005-09-14 23:27 ` "Read my lips: no more merges" - aka Linux 2.6.14-rc1 Redeeman
2005-09-16 7:44 ` Tomasz Torcz
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