[ardour-users] Ardour not using available memory?

Scott Helmke scott at scotthelmke.com
Sat May 1 13:35:57 PDT 2004

Whoops, I *did* have a Firewire dink, I just had to assemble it from my spare 
IDE disk and my Firewire CDRW drive.  It works pretty much exactly the same 
(CPU load, buffering, etc) as when mounted on the IDE bus in the computer.  
So no big win there.  :(   On the upside, once I found out how to mount a 
Firewire hard disk it was all quite easy.  

I also figured out why recording has a lower CPU usage - I dug through the 
options window and found that the "use plugins while recording" option was 
off.  Sure enough, systematically deactivating all plugins got the CPU use 
down from ~45% to ~30%, which is better but still not good enough for 3 
tracks playing back.  Gverb on one of the tracks seemed to be worth about 5% 
or more.

So how does Ardour do its buffering, then?  It sure does seem like it's 
always pulling stuff off disk while playing, and then when the track ends 
and I go back to the start there's a brief pause while it gets stuff from 
the disk again.  Should I be getting more benefit from OS disk caching?


On Saturday 01 May 2004 15:52, Scott Helmke wrote:
> Well, no Firewire disk to test, but I'll probably get one.  There's a
> small wrinkle in getting Firewire stuff to run under Fedora, but it's
> pretty simple thing to deal with.
> With a somewhat older 16Gb disk hooked up as /dev/hdd (slave to the CD
> burner) and set up as reiserfs I didn't see any real change in CPU use on
> playback.  Still appears to be a lot of disk activity just playing back
> 3-4 tracks, and when I first opened the project I got a couple of "disk
> stream" errors.  The session is over 1 Gb, but most of that is muted or
> even replaced tracks.  Ardour is now using 159Mb, according to top.
> On the up side, I recorded a track and the CPU use was only around 20-30%,
> as opposed to 40-60% during playback only.
> Any further ideas?
> -Scott
> On Friday 30 April 2004 17:47, Jack O'Quin wrote:
> > Scott Helmke <scott at scotthelmke.com> writes:
> > > I'll give that a shot; I've got a spare disk I can use.  With Fedora
> > > it's ext3 on /, which is pretty much the entire disk.  I don't have
> > > room in the box for SCSI, and maybe not even a second HD since it's
> > > one of those little Shuttle boxes.  I've gotten a Firewire CD burner
> > > to work; would a Firewire hard disk make sense?
> >
> > Probably.  No personal experience with it, but it seems like a good
> > solution for portable, hot-pluggable audio storage.  Fairly
> > inexpensive, too.
> >
> > I'd be interested to hear from those who've tried it.
> >
> > > So it turns out about half of my Gb of memory was held by tmpfs.  I
> > > can't see why the two tmpfs filesystems (/dev/shm and for jack) could
> > > need more than 100Mb or so, at a guess.  However, limiting them to
> > > 100Mb didn't have any apparent effect on Ardour's performance or on
> > > the CPU meter.  Ardour is still (according to top) using 150Mb.
> >
> > Probably half a GB of *virtual* memory.  No significant overhead in
> > that.

---- Scott Helmke ---- scott at scotthelmke.com ---- (734) 604-9340 ----
And you'll visualize not taking any chances
But meet them halfway with love, peace, and persuasion
And expect them to rise to the occasion
(from "Glad Tidings", by Van Morrison)

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