Dell, DPC Latency, and You

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Dell, DPC Latency, and You

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Update from Lionel: Below is John's original post on the topic of DPC Latency. Here is John's second post where he outlines the fix. To centralize the discussion, I closed comments on this post. If you have comments, please leave them at the updated post.

You may have seen some chatter recently about an audio issue on the Alienware M17x on Engadget, NotebookReview and Dell’s Community site. The discussions revolve around deferred procedure call (DPC) latency, and its affect on audio performance. We are aware of the issues customers are reporting, and are currently working to address them.

Some folks are using tools to measure DPC latency, and while measuring it is one thing, it may not actually cause performance issues. The few customers who have symptoms are reporting the following:

  • Audio stutters, clicks, pops, and drops
  • Frame drops while watching videos
  • Audio/Video desync during video playback

DPC latency is not an issue that is specific to Alienware or Dell. This is a complex problem to address, and there are no simple solutions. DPC latency can be caused by numerous issues including the system BIOS, a sound card or audio chipset, drivers, the operating system itself or a combination of those things.

We will continue to dig deeper into this. As we make progress on this issue, I'll report it here.

Update, 11/25: I just received a report from our engineering teams that the problem has been reproduced and has been narrowed down to two possible root causes. I should have more news for you next week!

Update, 12/2: Some good news! The engineering team has successfully recreated the problem and identified several causes. One root cause has been identified and can be addressed by a BIOS revision, and an updated BIOS is now being validated. The engineering team is hopeful that the other root causes will also be resolved via a BIOS change, and are working to confirm this so a full BIOS update can be implemented.

Update, 12/15: Sorry there hasn't been anything concrete to report, but I finally have something. My friends in engineering informed me this morning that a fix has been written and is now in the final testing phase. I've been assured that the fix will be ready for consumption in the next couple of weeks, barring any unforeseen incidents!

Final Update: Many of you have noticed the A03 BIOS revision has been posted on the drivers and downloads page. After installing this BIOS revision, please make sure you have the latest Broadcom wireless driver from the support page. These steps should resolve the issue for most users.

For those still having problems after doing the above, please contact technical support for further assistance.

Thank you so much for all of your patience. I apologize for the wait!

Update, 1/18: Just wanted to know this story isn't quite over yet. NVIDIA and Dell engineers are working together towards a driver fix, and this I was told today. I apologize for any confusion. Hopefully we can come to a complete resolution very soon. I'll update you as I hear more.

Update, 2/12: After participating in a conference call with the internal key players regarding this issue, I'd like to invite those who are still seeing this problem to message me personally with their service tag and case information, as well as a description of what you've done with support to try to resolve this issue since it began. I'd like to get that information into one place so we can expedite a resolution for those affected.

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Comments
  • While I'm glad you guys are finally responding seriously to this issue, I have a problem with the fact that this is an issue to begin with. It's a problem with the industry as a whole, and not necessarily specific to Dell, and that's a lack of testing on released products. I personally own an M17x and I find it unacceptable that on a simple Windows install using only Dell released drivers that audio playback (even while doing nothing at all) skips and stutters the way it does. IF I were tweaking or deviating from factory spec, I could understand that, but it's totally stock!


    I will add that I love the machine otherwise. It meets almost every other requirement I was looking for in a notebook machine. All I need it to do now is play my music without ruining the experience.

  • Hi John

    First it's good to see you here, and thanks for your update. It is a pity that however that it takes visibility from so many dissatisfied M17x owners over several month to contact other publications in order to get a response from Dell/Alienware for some traction, so I hope a valuable lesson is learned here too..

    To be constructive, rather than open the floodgates for anyone with a problem, what information can we, your premium customers (in my case after spending £4100) do for you Dell/Alienware to identify and more quickly assist in resolving this specific and well publicised issue? We are frustrated because, as many of our community are in the IT sector and pretty tech savvy, we would like to offer our expertise freely if used constructively and objectively towards a proper resolution - as a two way street.

    I appreciate as many of us will, that you rely also on updates from OEMs such as nVidia for drivers, and so this responsibility should be shared there too, as this is hurting your customers current and future potential sales and reputation.

    This is a great opportunity to work with your customers, and we will respond, and try to separate the understandable frustration from the constructive feedback. Please let us know what you need in terms of testing and feedback and we will rise to the challenge.

    Kind regards

    Trelawney (UK)

    P.S. The DPC issues reported may not all be related to the same root cause, however as the M17x is a gaming platform, it is also during games that such stutters have been seen to occur and cause framerates to briefly freeze. In my experience, my stutter issue is due to the RAID 0 Seagate drives 'clunking' / parking several times a minute and then trying to perform a cache. Alienware tech support tell me is quite normal and a known 'issue' with certain Seagate drives. Not sure I agree here even though SMART shows they are otherwise fine, but I hear varying reports of the same too which may for some be part of the same symptom. 

  • Thanks for dropping by!

    @ Trelawny - rest assured that there are teams of folks trying to dissect the issue and get it resolved. The best thing you can offer is your continued patience :-)

    @ D. Hymon - You make some good points. There are a lot of opportunities to learn here, and not just for Dell. A PC is a complicated piece of machinery that has "evolved" over time in pieces, and as a result, sometimes things "crop up" from the resulting complexity. The discovery is sometimes a painful process, but such is the nature of the beast.

  • The poster child for "lack of testing on released products" is Microsoft.  Just look at Vista.  Basically all of their prior operating systems from 1998 on were released as a massive public beta-test.  It all has to do with the competitive pressures and the need to be first to market to garner or keep market share.  Is this the best way to do business?  No.  I'm sure a lot of savvy tech people at Microsoft, Dell, and other high profile companies would love to release a 100% flawless product, but the bean counters have other ideas.  They have to answer to executive management, who answer to the powerful shareholders looking for a return on their investment.

    I'm not excusing these companies for this short-sighted behavior, but it's the current reality of the American (and global) economy.

    Back on topic, I sure hope that these critical issues are fixed soon.  I've got $4,500 just waiting to buy an M17x, but I won't do it until I know a fix has been released and works correctly.

    And, to throw more fuel on the fire, when will the M17x get the mobile i7 chip?  Smile

  • Thanks for the post.  Some of us have contacted Dell prior to this and were told a BIOS update was already in the works and is currently one or two weeks overdue.  Could you please confirm this?

    Also, if you need anything, my M17x is also available for testing. 

  • Who told you this? At this time the only information available is what I've discussed on the blog. If others are giving out different information I'd like to get to the bottom of it and correct it.

    And we've got plenty of M17x's, no need to give yours up Wink

  • This Dell Community forum post. Scroll down to middle of page for post dated 12 Nov 2009 09:29AM by Dell-Bill B.

    Quote from that post : "It's going to be a matter of waiting for the 1737 latency to be fixed in the new BIOS. Once that is solved, they will apply the lessons learned to all the other affected platforms. I put the 1737 through first and let the engineers know we would be pushing all other affected platforms through after we have a fix for 1737."

  • I read this in our NotebookReview forums.  Here's the actual thread:

    http://forum.notebookreview.com/showthread.php?t=408300

    http://forum.notebookreview.com/showthread.php?t=408300&page=13 - A forum member states he was assured the BIOS update is in the works and was due out the previous Friday but will likely be delayed.  Dated 11/08.

    http://forum.notebookreview.com/showthread.php?t=408300&page=14 - here's some screenshots of my machine's latency as I installed Win7 and drivers.  The last page is a member stating he was assured a BIOS update is in the works - this post was dated 11/08.

    As you can see, we've tried plenty on our side.  We've done drivers, installs, powermizer, tweaks, etc.  NOTHING has fixed the latency spikes - some have reduced but that's it.

    I will request that the two posters either PM me or post the names of the people they talked to.

  • @erwaneilA - I've spoken with Bill at great length about this issue. I think it's important to state that the latency issues/lessons learned/BIOS update Bill is refering to there may have a completely different root cause and fix than what folks are seeing on the M17x. This is a complex problem with many possible causes, so silver bullets aren't likely to appear.

    @Lord_Zath2 - Please do. This is a confusing issue, and I'd like to make sure everyone is on the same page.

  • From one of the forum members.  Unfortunately, he hasn't supplied a name :(

     

    I've been in weekly-biweekly contact with their upper levels of support for over two months now. (it's mostly been with Alienware Resolution Experts and their associated Engineers) I feel bad bugging them all the time... but this issue has really gone on too long and really gotten out of hand. They keep telling me they are working on it

    When I first report this to them a couple of months ago... they said at that time they weren't aware of it until we brought it to their attention.

    Maybe the support staff at Dell doesn’t correspond with the support staff at Alienware? (I was under the impression that Dell was letting Alienware deal with all the Alienware support)

    When you dial the 800wwwdell number and enter the service tag for an AW system... it automatically transfers you to AW support

  • Thanks, John.  Yes, I certainly understand the complexity of the issue and that one size does notnecessarily fit all here.   Two questions 4 U:

    Have you, or other Dell engineers/techs, successfully replicated the performance issues that some M17x owners are experiencing?  I'm not just talking about the DPC latency meausrements, but the actual noise popping, drop-outs, and stutters?

    Would it be worthwhile to set up a registry database of M17x owners  to collect config data from those who are experiencing the problem to see if a general trend can be discerned (e.g. quad cores vs. dual cores, Vista vs. 7, etc.)?

  • @erawneilA -

    To my understanding there has been some measure of duplication, but on what configs and with what consistency I really can't comment on.

    Your idea may have merit. I'll fling that one at my friends in engineering. Big Smile

  • I'm surprized there is no information in THIS thread that is actually technical.

    Shouldn't this thread be the official one? So far, we have one person saying its the Hard Drive?? I'm pretty sure it has nothing to do with the harddrive, and the problem ONLY happens if the NVIDIA drivers are installed. How come noone is talking about this?

    Uninstall the NVIDIA drivers for the GPU and the audio stutters are gone. Now of course, a gaming laptop without a GPU is pretty useless....

  • I'm not really sure why a technical dissection of the existing problem would help, but this is the official thread.

    There's a fix on the way. They've identified two possible causes, and once they've come up with a fix, they'll look at any possible problems the fix causes to make sure the fix doesn't cause more problems than it solves.

    On that note, just because uninstalling the NVIDIA drivers solves the issue for you, that doesn't necessarily mean NVIDIA drivers are causing the issue. We could digress on that forever... I think that's why this thread isn't more technical. It's just not constructive to do that.

  • Yeah you may be right... I suppose when its being discussed, I get a false sense of "its definitely being worked on" while the opposite gives me the opposite feeling.

    When I brought my laptop in to work the day after I got it to show everyone (I work in IT), it got a LOT of attention because of the flashy look and everyone wanted to see it. Unfortunately, many of the geeks there think that Alienware is bad quality now because of my inability to play audio without pops, stutters and clicks, and have fluid video playback. Most of them would never buy one now, eventhough I've shown them all of the cool aspects of the system otherwise.

    I'm hoping that I can prove them wrong because I had been raving about Alienware for months before the purchase, and I still think that its the best computers out there... I just want it to function the way it looks :P