[linux-audio-user] Advice needed re: latency tuning/optimization, esp. video

RTaylor ricktaylor at speakeasy.net
Tue Feb 17 01:56:43 EST 2004



 :} I have one just like it... {Gigabyte no asus {8 drives}}
 ...You need a better soundcard.
  

On Mon, 16 Feb 2004 20:15:31 +0100
Robert Jonsson <robert.jonsson at dataductus.se> wrote:

> Hi,
> 
> måndagen den 16 februari 2004 19.24 skrev Chris Metzler:
> > Hi.  I'm looking for some advice on how to deal with latency introduced
> > by graphics activity.
> >
> > My setup:
> > AMD Athlon XP 2000+
> > ASus A7V333 Raid+ Motherboard
> > 1 GB Corsair CAS2 PC2700 RAM
> > Creative SBLive 5.1 sound card
> > Matrox Millenium G550 video card, AGP4x, 32MB RAM
> > 1 WD800JB IDE disk (80 GB, 8 MB cache); 4 WD1200JB IDE disks (120 GB,
> > 	8 MB cache each)
> > Kernel 2.4.23 + preempt + lowlatency, XFree86 4.2.1
> 
> To summarize, your system should rock.
> 
> <...>
> > The sound card shares IRQ 10 with the USB2 bus; but I have no USB
> > devices of any sort.  On IRQ 9 are two of my four IDE channels.
> 
> This is probably not optimal, if I understand correctly irq10 is a bit down in
> 
> the priority list, if you haven't read the lowlatency howto, do that.
> 
> <...>
> > This result surprises me.  I'm using a video card that's supposedly
> > very very good at 2D stuff -- indeed, it's the video card that RME
> > recommended as recently as last year as their card of choice for
> > audio workstations.  It's definitely open at AGP 4x (XF86 wants to
> > open it at 1x unless you explicitly say in the config file that you
> > want 4x).  32 MB isn't a huge amount of video RAM, but I would think
> > would be fine for 2D stuff.
> 
> That a card is good for graphics doesn't necessarily mean that it's good for 
> audio. That RME recommends it points to that the card should be well behaving 
> hardware wise. Things to check:
> - That it has an irq that has lower priority than the audio card ... might not
> 
> be possible with agp ?
> - Try and change the AGP setting. Faster isn't necessarily better.
> 
> The most probable offender is the driver though, I don't know if there are 
> multiple drivers for this card so you could try another?
> 
> If you have a graphic login (e.g. you login directly to X) you should check 
> that xdm/kdm or whatever display manager you are running does not have 
> elevated priority. Mandrake does this as has been noted here before, for 
> mandrake it's in:
> /etc/X11/xdm/Xservers
> the line is
> :0 local /bin/nice -n -10 /usr/X11R6/bin/X -deferglyphs 16
> -10 is wrong 0 is _more_ right.
> 
> If you are running KDE or GNOME there might be issues with certain functions 
> of the desktop environment. I'm running KDE myself with no problems but 
> others have reported problems with both.
> 
> I guess you could try different graphical settings also, amount of colors, 
> display size... no solutions but it might help to identify the perpetrator.
> 
> All I can think of right now. Hopefully someone with a similar card/setup can 
> comment with better ideas.
> 
> /Robert
> 
> 
> 
> 


-- 
 See these tears so blue. An ageless heart that can never mend.
 Tears can never dry. A judgement made can never bend.
  ...
 And I've been putting out fire with gasoline...
  {Dave}




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