Subject: Re: [Fwd: [linux-audio-dev] info point on linux hdr]
From: Eric W. Biederman (ebiederm+eric_AT_ccr.net)
Date: Sat Apr 15 2000 - 03:12:01 EEST
Andrew Clausen <clausen_AT_gnu.org> writes:
> Hi all,
>
> Any comments?From: Paul Barton-Davis <pbd_AT_Op.Net>
> Subject: [linux-audio-dev] info point on linux hdr
> To: linux-audio-dev_AT_ginette.musique.umontreal.ca
> Date: Fri Apr 14 07:10:10 2000 -0500
>
> i mentioned in some remarks to benno how important i thought it was to
> preallocate the files used for hard disk recording under linux.
>
> i was doing more work on ardour yesterday, and had the occasion to
> create some new "tapes", of lengths from 2 to 40 minutes.
>
> the simple act of creating 24 5 minute WAV files on ext2, files in
> which every block has been allocated, takes at least 1 minute, perhaps
> as much as 2. i create the files by first opening them, then writing a
> zero byte every blocksize bytes (blocksize comes from stat(2)), except
> for the WAV header at the beginning.
I'm confused. You wrote what is conceptually 24x5=120 minutes of audio
data in 2 minutes. So you have 60 times the performance you need.
What is the problem?
> i hadn't done this in a while, but it reminded me of the
> near-impossibility of expecting the FS code to allocate this much disk
> space in real time under ext2. If someone knows of a faster way to
> allocate the disk space, please let me know. Its not that I have a
> problem right now, just wanted to point out this behaviour.
If you blocksize was 1k increasing it to 4k could help.
Eric
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