Dell Latitude DPC Latency Issues

Interestingly in my case the use of LAN seems to smoothen the latency.
Made the attached screenshot, while moving a large file through the network. The DVD-drive, which is the primary cause for latency problems in my case, was removed in this scenario.

 

Which wireless card do you have?

I've heard that the Intel ones don't cause this problem. The Dell cards do though.

 

Well this DPC is new to me so i tried a checker in my Latitude D820 and it haves the same problem, but if i take off the DVD/Modular bay it corrected btw I have Vista 64

 

I just spent another few hours working at this, and here is what I found:

Using the 8.2 Intel Matrix Storage Manager driver (A01), I only get the DPC spikes every few seconds. It doesn't seem to matter whether or not the optical drive is connected or whether the module bay is enabled in the BIOS. With this version, however, disabling the eSATA port in the BIOS seems to help - slightly. However, there are other reasons for upgrading to the 8.7 driver, related to power savings, etc., so downgrading the driver should not be considered a solution.

Using the 8.7 driver (A03), I get almost constant >8ms DPC latencies. These instantly fall below 1ms the moment I remove the optical drive, and raise back when I reinsert the drive. Leaving the drive inserted but disabling the optical drive in the BIOS has the same effect. I just received a replacement DVD+RW drive today from Dell, but both the old and the new give exactly the same results.

Changing between IIRT and AHCI mode in the BIOS doesn't appear to have an effect on anything. Changing to regular ATA mode does seem to be the best solution at the moment, though! In this mode, the Intel Matrix Storage Manager drivers aren't even needed, applicable, or usable. I average less than 0.5ms. I still have very rare spikes, but only to 2.017ms after running for several minutes. If I understand correctly, however, this mode means limited or no hot-plug functionality, etc. While I don't currently have an eSATA hard drive to test this on, I plan to get one in the future - if we can get these issues resolved.

Changing between Vista 64-bit or 32-bit doesn't appear to change anything. I've read mixed results concerning the use of Windows 7, but I don't consider this to be a solution as it isn't even a released OS yet.

I think it is clear that this issue is specific to the Intel Storage Matrix Manager driver, though it may also depend upon Dell's modular bay. I just completed another chat session with Dell, who promised to re-escalate the issue and to follow-up with me. (We'll see.) I also just submitted this through Intel's support form for the chipset, though I fully expect to only receive a form response stating that it needs to be worked through Dell. I'll post back if and when I hear anything back from either Intel or Dell.

 

I've come to the sad realization that Dell probably isn't going to do anything about this. I've been holding on to an open case # for several weeks now. Despite several requests for updates, I haven't received any new information, nor has anyone even given me the courtesy of following up.

However, it seems that Dell is just using the Intel stock drivers - so I took this issue to Intel directly. They've followed up to my original request 3 times so far, mostly asking for additional information. I now have a separate open case # with Intel. The last update says it has been escalated to their research department, and that they will contact me again soon. (A sincere "Thank You", Intel!)

 

Hi

I'm new here. But found the forum due to my problems with my Saffire LE sound card and my new Dell Latitude E6400.

But I have come to exactly the same conclusion as you have ziesemer. I am now running XP Pro in ATA mode.

And I really want to thank you for taking this issue up with Intel and Dell. I hope that Intel can be bothered fixing it cause it's really annoying that it's not possible to use SATA if you plan on doing audio stuff.

Let me know if there's anything I can do. Would it help if I contacted Intel as well?

Best
Matthew

 

Please do - both Intel and Dell if possible, and consider sending them links to this thread. I'd think the more visibility, the better chance we have of getting this fixed - and hopefully in a reasonable time.

Thanks!

 

Good deal; just sent these details to our Dell Rep; we don't have many Precisions at work, but thousands of E series Latitudes.

 

Found out that the DVDRW was causing obnoxious amounts of latency:
http://dingo9.net/faultysata.jpg
http://dingo9.net/faultysata2.jpg
(the green is where I removed the drive -- and the red is where the drive was placed back in the machine. It's like night and day)

And then once the drive remained removed, I had random spikes which I've identified as the Broadcom 1397 Wi-Fi card to be the culprit.
http://dingo9.net/faultywifi.jpg
http://dingo9.net/faultywifi2.jpg

Whoops! I have a Precision M4400 -- I'll go post in the appropriate forum. My mistake.

 

Not really a mistake. The underlying hardware platform is the same for the new Latitudes and Precisions.

John