[ardour-users] Latency: AGP vs PCI video card and XFS journalling vs not

[delire]

i would certainly be disappointed that my PCI graphics card would hit
the bus so hard that such great headroom was practically
worthless!

i don't know how XFS compares to EXT3, but i doubt the PCI graphics card is
such a guzzler as to eat your clock cycles like this. 

i'd try out EXT3 before opening your wallet for a 3D card.

(jeeziz dual SCSI!)

delire


On Sun, Feb 22, 2004 at 03:51:26PM -0500, lee at fallingforward.net wrote:
> Your system has far better hardware than mine and I can get JACK down to
> about 11ms latency with no dropouts. It seems our differences are that I
> have an AGP video card and ext3 filesystem. I would highly recommend an
> AGP video card, I got a Radeon 9000 new for US $80.
> 
> -lee
> 
> On Sun, 22 Feb 2004, Eric wrote:
> 
> > I have built a box that I thought would be able to support some very
> > low-latency recording in the eventual hope of software monitoring with
> > some effects in the loop (is anyone able to do this?).  It's a dual
> > athlon 2400 w/ 1GB of DDR266, dual 10K SCSI drives, and my M-Audio
> > Delta66.  I'm using the Debian unstable packages (jack 0.94 and ardour
> > beta9+3) with a 2.6.3 kernel and have played around w/ all the
> > standard latency issues (no extra stuff running, swapped PCI cards
> > around for interrupts, etc.).  However, I'm not able to go lower than
> > the default jack 3 periods of 1024 (with rt enabled, obviously) when
> > working on my typical projects of 8-12 48KHz mono tracks, even without
> > any effects in the loop.  It is dissapointing to have to go back to
> > hardware monitoring w/ no effects...I have two questions:
> >
> > 1.  Could it be my old Voodoo3 PCI video card is hogging the bus?
> > Rendering the mixer window definitely has an effect on my audio...if I
> > drag it around or minimize/maximize it I can actually slow down the
> > audio playback (which was surprising to me) or cause xruns and
> > timeouts.  I've taken to just minimizing everything while I'm
> > recording.  I didn't care about my graphics card, but now I'm
> > considering an AGP one (nVidia GeoForceFX 5600 or ATI Radeon 9700)
> > just to try and improve this...
> >
> > 2.  Could it be my XFS filesystems?  If I have 8 or so tracks on one
> > drive, it can't even handle playback w/o giving disk errors.  I've
> > tweaked all the XFS options, and currently have a large (64MB) log for
> > each filesystem that resides on the opposite disk.  Would turning the
> > log size up or down help?  Is there a way to just turn off journalling
> > in XFS, or would ext2 be better?  I did notice that exporting to my
> > default param (i.e. small log) ext3 root partition seems to be faster
> > than to my XFS.
> >
> > --
> > http://ir.iit.edu/~ej
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