Dell Latitude DPC Latency Issues

Did you work through the problems listed in the poll? Start with the Intel Storage Manager software.

John

 

Apologies for cross-posting, but I felt that this thread on the Dell forums might be relevant here. It's just a workaround for the Intel Matrix Storage Manager issue, but a useful one nonetheless - it enables the Latitude E6510 to be used for pro audio.
Cheers,

B

 

Here's how I got rid of DPC delays on my Dell Latitude E4310 on Windows 7 64-bit.

For my system, in general the DPC Latency Checker graphs were generally green but there were random 20,000-60,000 millisecond spikes every
2-5 minutes. These spikes would cause a sound drop-out either during recording or playback (or both) and COMPLETELY ruin the ASIO driver my sound card uses, so that the sound card would only put out a screeching sound on top of the actual sound after this DPC spike had occurred. Sometimes it would fix itself over time and sometimes not. The only sure-fire remedy was to re-set the ASIO driver through its control panel but that's a very annoying thing to do every few minutes.

So after two days of trying all kinds of workarounds I have finally succeeded to get rid of DPC delays.

For completeness' sake, here's also the steps I did that did not produce any results for me. Using DPC Latency Checker and xperf I tried all of the following:
a) disabling all network interfaces - got rid of ndis.sys delays, but still there were acpi.sys, iaStor.sys and ntoskrnl.sys delays
b) disabling DVD disk drive - no noticeable results
c) fixing computer on High Performance power mode - no noticeable results, acpi.sys spikes still remained
d) upgrading all drivers (WiFi, LAN, DVD drive) from Dell website - no noticeable results
e) switching SATA option from RAID to AHCI in BIOS - Windows would not boot, so had to switch it back
f) disabling almost all devices in my system - still the spikes remained
g) installing the latest Intel Rapid Storage Technology drivers from Dell website - no noticeable results
h) following DAW set-up guidelines for minimizing latency from Windows 7 Tuning Tips for audio processing (mostly the power settings part) - no noticeable results

I was about to give up but as a last option I took the risk and installed the latest Intel Rapid Storage Technology drivers from intel.com website (NOT from Dell). I read from earlier on in this thread that people have tried updating Intel Matrix Storage Drivers directly from Intel website but now the name has been changed (from Matrix Storage to Rapid Storage, or that's at least how I understood it) , so I was not sure it would not break anything on my system. I noticed there was also a "pre-os" version of the driver available on the website but I did not get that.

And ... (drumroll) ... after installing the driver and monitoring with DPC Latency Checker again, no DPC spikes appeared anymore!

So now my laptop can be used WITH WiFi, LAN and the DVD drive enabled. Also, which is very convenient, it is running on a Balanced power plan. There no sound latency issues at all. I'm really relieved. By the way it's pretty weird that one storage driver can have an impact on so many components and it's really hard to believe that updating such a driver would solve the problem but that's how it is.

After monitoring the system for an hour the highest spike was 4500 milliseconds - and that was probably just once. I have an external sound card which is now working great, with ASIO driver delay of 128 samples - the lowest possible with the driver! There now are virtually no drop-outs and the quality is flawless, whereas before I would not be able to play for half a minute without pops, crackles, and complete drop-outs.

Good luck to anybody who is trying to solve this issue - the solution may be hard to find but it's there.

 

Hi guys,

Many thanks to all contributors on this massive collection of latency know-how. For me at least I found the core reason for all issues. Reason was the integrated MMC/SD card reader by O2 Micro. Deactivating it in the device manager immediately resolved all issues. Before disabling it, DPC latency tool presented yellow and red bars all the way. Seldom some lonely green bar inbetween.

Disabling it lead to latencies of 100us to 200us in average, peaking up to about 500us after some minutes of testing bluetooth audio streaming and web surfing via WLAN. No problem at all.

My configuration:
DELL Latitude E6420 with NVidia NVS4200 GPU and Intel i7

Thanks for the inputs from all of you and good luck on your search!

 

Thanks for this post on improving the latency for the E6420! It helped eliminate the latency issues on my Latitude E6420 as well. I do get a random spike though to 73550 in DPC when the normal is around 100. Not sure what that is about yet.

 

ur welcome

The spikes come from ndis.sys, some network protocol layer. Stop background network activity to reduce them or disable WLAN/NIC for 100% elimination. Further latencies do come from DX graphics (e.g. NVIDIA) or bluetooth activity.

You can eliminate all latency issues, but what's left to use the computer for then?

 

For us on all our e6420 WinXP or Win7 it is the O2Micro SD card reader causing the latency.
You can disable it and it goes away and when you re-enable the latency issue does not come back until you restart the computer.
We have the latest drives that Dell is offering.

Did anyone find a resolution for this?
Thanks for any insight.

 

Well I just noticed Dell released the A05 firmware update on 7-1-11.
However it did NOT resolve the issue.