DPC latency question

Your average is fairly low for a laptop. It is the spikes that you are looking for.

As a comparison my desktop runs about 13µs and never spikes above 40µs.


best regards,
mike

How does it do without X1 running?

 
The first time was without X1 running, the second was with X1 running. I was not playing a project, it was just opened. Both times were about the same. I am guessing that having the wireless combo turned on when X1 was open caused the spikes to 600+. Should I try it with a project playing or would it make a difference. I will try later with a USB interface connected and can have a project running. I can use on of the Cakewalk projects running if you like, then you will know exactly what is going on. I will connect the UX-2. I will be more than happy to try anything you want.
 
edit: I misread your question. In the OP, the first instance was without X1 running, the second was withit running but also the computer was online when X1 was running. There really was very little difference between the two. Let me know if you want mr to try something. BTW, I use the HP updater once a month and it does a "tune up" FWIW. Last time it updated the bios and some other stuff. I keep it set to delete temporaryinternet files etc everytime I close a session. Don't know if any of this matters though. 
Also, this machine is an HP Pavilion dm4-1165dx.
 
Thanks for the help.
 
Julien

Hi

I have a DPC latency issue on my desktop running Windows Vista 64bit Home premium and Sonar 8.5.

It seems to be resolved if I run LatencyMon from Resplendence Software. However, if I unload LatencyMon the latency reappears! I have confirmed this using dpclait.

I have not yet found an explanation for this, but as a short term fix you may want to consider installing LatencyMon when running Sonar.

RogerL_UK

It seems to be resolved if I run LatencyMon from Resplendence Software. However, if I unload LatencyMon the latency reappears! I have confirmed this using dpclait.

That's kind of strange. I don't see anything in the LatencyMon overview that indicates it will affect DPC latency, only that it will report what processes are causing what part of it.

I've run it before, and not noticed that it had any effect on latency.

The process of identifying and removing latency-causing hardware and/or software is one giant pain in the rear, however these issues are well-reported on the web and are usually solvable.

I had a laptop that had massive spikes occurring quite frequently and were up in the 2800 range.  These had a disastrous impact on sound quality, and it rendered the laptop unusable for any music performance or production, despite having a solid-state hard drive, optimized memory (services carefully selected/disabled as needed) and 4GB of memory.  I was also using an external audio interface.

The issue ended up being a hardware issue where the BATTERY for the laptop was somehow causing these massive spikes.  The INSTANT I removed the battery, the problems went away.

The point is that there a a number of causes to latency issues, but that solving these issues is generally a linear process, and that there some tools and tips available to detect and assist in resolution.

1.  Make sure you have as much memory available as you can
2.  Make sure you carefully evaluate loaded applications (antivurus, other startup loaded aps), for potential disabling during music performance/recording sessions.
3.  Check latency, using free tools such as DPCLat and LatencyMon.
4.  Carefully look at the Windows services configured to run on your system, and if needed try to pare down some of the services that don't need to run during music sessions.  Things related to network services and print spooling come to mind - there are lots and lots to go through.  Be VERY careful not to disable something needed to run Windows properly.  If unsure, look up the service names on the web to determine whether or not you can safely disable - and also to find out what some of the services do.
5. Use an external audio interface to have A/D and D/A conversion processed through dedicated hardware, as opposed to making your computer's CPU do all the work.
6.  Look on the web for tips on optimizing computers for audio processing.  There is a lot of information out there on this.

Good luck with getting things set up and working without audio problems.

robert_e_bone

The issue ended up being a hardware issue where the BATTERY for the laptop was somehow causing these massive spikes.  The INSTANT I removed the battery, the problems went away.
 

Are you sure it was a hardware problem. A number of people have reported on various forums that the Microsoft ACPI-Compliant Control Method Battery device driver causes huge spikes. That driver is technically speaking software, and removing the battery is throwing out the baby with the bath water. The laptop should run on battery with the driver disabled, but you will get no low battery warning.

Since this was posted in April I have learned that turning off all my WIFI related processes stops all the spikes. I run between 90 and 105 μs consistantly. If you just disconnect from the internet the WIDI will try to reach out and touch someone, and it causes the spikes at least here.
 
J

jbow
Since this was posted in April I have learned that turning off all my WIFI related processes stops all the spikes. I run between 90 and 105 μs consistantly. If you just disconnect from the internet the WIDI will try to reach out and touch someone, and it causes the spikes at least here.
 

That's not bad for a prefab laptop.
A well-configured desktop will be significantly lower (3 to 24 uSec - no peaks above 40 uSec)
The lower the latency you're running (and the heavier the load), DPC latency becomes more of a factor
To work effectively at a 64-sample ASIO buffer size or lower, DPC latency needs to be low and consistent (no large spikes).