linuxaudio.org

On Wed, Sep 09, 2009 at 03:08:58PM +0200, Arnold Krille wrote:

quoted text
> I think for plain recording it shouldn't make a difference. When

> playback occurs, there are multiple files involved and it could be the

> seeks also depend on how the file systems lays out the files on disk.

> So that might have an influence. If this information isn't cached in

> ram.

Yes, the ideal is that the tracks being played are cached in RAM so that

no disk access is required.  The recording track would be creating a

file that would be periodically written to disk.
(LWN handled something relevant to this today, in an article by Valerie,

subscriber only content at the moment but I imagine it will become free

in a couple of weeks from now ... http://lwn.net/Articles/351422/ ...

but the interesting thing there was that with ext3 and data=ordered,

data reaches disk within about five seconds by default ... and in the

previous article http://lwn.net/Articles/322823/ which is freely

available, is the mention of /proc/sys/vm/dirty_writeback_centisecs ...

for a multitrack studio scenario with backup power I'd increase this

value immediately prior to commencing the recording, so as to encourage

any writes to be buffered ... and restore it to default on transport

stop).
Actually, an even better ideal is to have a hard disk for each track,

and use a filesystem with delayed allocation ... this would minimise the

latency on the track read requests, and keep the disk heads sitting over

the area they will be next needed.
--

James Cameron

http://quozl.linux.org.au/

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