Dell Latitude DPC Latency Issues

Discussion in 'Dell Latitude, Vostro, and Precision' started by ziesemer, Jan 14, 2009.

?

What have you determined to be the cause of the DPC Latency Issues, if anything?

  1. Nothing - still having issues.

    22.7%
  2. Video card / GPU

    5.5%
  3. Intel Matrix Storage Manager - Driver

    35.5%
  4. Intel Matrix Storage Manager - Software

    17.3%
  5. eSATA

    4.5%
  6. Wireless / 802.11

    26.4%
  7. Bluetooth

    2.7%
  8. Optical Drive / DVD

    22.7%
  9. Audio card

    0.9%
  10. Smartcard reader

    0.9%
  11. ExpressCard

    0.9%
  12. PC Card / PCMCIA

    0.9%
  13. Firewire

    0 vote(s)
    0.0%
  14. Suspend / sleep issues

    0 vote(s)
    0.0%
  15. WebCam

    0 vote(s)
    0.0%
  16. Fingerprint Reader

    0 vote(s)
    0.0%
  17. Pointing Devices

    0 vote(s)
    0.0%
  18. USB

    0 vote(s)
    0.0%
  19. Other #1

    7.3%
  20. Other #2

    0 vote(s)
    0.0%
  21. Other #3

    0.9%
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  1. micro_cuts90

    micro_cuts90 Newbie

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    I HAVE THE ANSWER

    I have been lurking all day with this same problem, I found the answer for me so I registered to share it.

    Shutdown, take your battery out, connect mains and power up. 15 second latency spike cured and can record 8 tracks for 30 minutes+, glitch-free. I think it stops some dell battery monitoring program that causes the epic spikes.

    I hope this works for everyone else.
     
  2. nordberg

    nordberg Notebook Enthusiast

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    There might be something to this. I just did a clean install of Windows 7 and installed a very minimal set of drivers. Wifi / bluetooth are completely disabled.

    I was seeing latency numbers maxing out at about 450 in dpc latency checker. Right now I'm running on battery and I'm seeing max numbers of 800 to 900.

    After I run the battery down some more I'm going to restart and see what the numbers are while charging and then check it out while fully charged.
     
  3. Dell-Bill_B

    Dell-Bill_B Guest

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    I wonder what happens if you disable "Microsoft ACPI-Compliant Control Method Battery" under Batteries in Device Manager.
     
  4. ziesemer

    ziesemer Notebook Consultant

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    Seems to be another cause to DPC latencies that I never realized before - the Fn keys and other ACPI functions. Copying over from the "E6400 overheating throttling" thread:

    Testing for these DPC latency issues should be a requirement before Dell releases any new drivers or BIOS updates as a standard regression test.
     
  5. david714

    david714 Notebook Geek

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    You should be able to find the offending driver easily using the microsoft tool kernrate or xperf. It will show how much CPU each driver is using.
     
  6. slander

    slander Notebook Guru

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    Except that the problem is not with one but multiple drivers! Check out the following two xperf screenshots. The first one is sorted by Actual Duration, and the second one by Max Actual Duration.

    [​IMG]

    [​IMG]

    I would really appreciate Dell-Bill to give his input on this. I can't believe I am the only one suffering from this problem! :(
     
  7. ziesemer

    ziesemer Notebook Consultant

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    Unless I'm missing something, both screenshots show NDIS.SYS as the top result, which is actually the same driver. Or do you mean both NDIS.SYS (from both these images), and ACPI.SYS (from elsewhere on this thread / forum)?

    You probably need to expand the detail for NDIS.SYS to see the actual offending cause, as there are several drivers that will all show as part of this. ~150 seconds also seems like a very long sample period for what is trying to be found here. Instead of showing a spike (which can cause drop-outs, etc.), all this really says is that the networking subsystem was somewhat busy over that time period - which could actually be somewhat normal if the network is in use.

    You should be able to re-display some graphs for shorter time periods (~10 seconds) from the same existing capture, and hopefully better demonstrate any DPC spikes.
     
  8. slander

    slander Notebook Guru

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    Thanks for your reply. I was hoping to draw attention to:
    1. The high values of Max Actual Duration (and Actual Duration) for a bunch of drivers; the max DPC latency is as high as 2208us for NDIS.sys alone. I read on this forum that according to MS requirements, no driver should have a DPC latency of greater than 100us and at least four drivers are guilty of not obeying this limit.
    2. The high interrupt counts for HDAudBus.sys. Why is that?

    All I want is to be able to be able to stream a wav file at low latencies of 3-6ms (using ASIO4ALL in my DAW software) when nothing else is going on. If I try to do that, I get a pop/click/crackle almost every second. I also can't listen to an MP3 in VLC without getting a crackle every 3-10 seconds.

    I have disabled almost every likely culprit in order to find the root cause of the issue. Check out my Device Manager:

    [​IMG]

    Inspite of doing this, my DPC Latency Checker often looks like this:

    [​IMG]

    How can they market this substandard notebook as a high-performance product?
     
  9. steve_proto

    steve_proto Newbie

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    Dell Vostro 1220. 2.4GHz, 4Gb, Mobile Intel 45 Graphics, Samsung SSD PM800 128Gb, Win7 Pro.

    Hi all. I'm having a nightrmare with my New Dell Vostro 1220 and DPC Latency. I installed my Native Instruments and Ableton software, then plugged it into my keyboard and audio interface and it immediately had pops/crackles/dropouts. I found the dpclait software and ran it and It shows spikes at 4000 us every 4 seconds. I've found loads of posts about it, both here on the Dell community and other forums. I've used the dpclat tool to monitor my DPC as I've tried the following to resolve it with no success:

    1. Disabled everything in Device Manager that can be disabled one-by-one and collectively

    2. Run the system with and without the battery plugged in

    3. Updated all the drivers I could, both from the Dell Drivers Support Page and the OEM support pages

    4. Reinstalled Windows 7

    I got the laptop on the 23/12/09 and logged a call with Dell Support as soon as I found out, but they feel that this isn't a problem with the laptop, but rather a problem with my software. I tried to explain that there is no software on it and that the dpclat software is just for testing DPC latency but I don't think I have managed to communicate this to them!

    I've found various 'fixes' like disabling ACPI, throttling the Processor, installing Windows Diagnostics tools to work out which process/program is causing the spike, but none of them work for Windows 7/me:

    I bought this laptop specifically to do music and find that music is the one thing it can't do!

    Does anyone know of anything else I can try?

    Thanks

    Steve
     
  10. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    1. Did you get the latest matrix storage driver from Intel?

    2. Is there any firmware update for the optical drive?

    3. Try disabling hardware at the BIOS level.

    John
     
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