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6 Posts
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18185
June 15th, 2011 17:00
Precision M6500 - High DPC latency causing audio stutter problem, intermittent freezes
I received my M6500 a month ago and wow, this thing has been a real challenge to work with. The configuration is an i7-940xm (Quad core extreme), 16GB of RAM, FX3800 video and nothing else special that I can think of. The first issue I ran into was the laptop would BSOD while sitting there idle (stop code 0xc00...24) which I solved with a special hotfix from Microsoft. I have updated every driver on this laptop to the latest I can find from NVidia and Intel.
Right now, listening to music or doing anything else that requires some reasonable consistency runs into constant problems with stuttering and delays. I've been using DPC Latency Checker v1.3.0 and it indicates that whenever this stutter occurs, there is a *ton* of high latency "Delayed Procedure Calls". Folks state that DPC latencies should be less than 500 micro-seconds, preferably no more than 100 micro-seconds. I'm seeing DPC's maxing out at upwards of 600K micro-seconds, with most storms spiking off the chart above 16K micro-seconds. :emotion-9:
Some have termed this a "DPC Storm" when it occurs, which sounds like it's not too far from the truth because of contention issues with drivers hogging the machine trying to get their tasks done. Research to date indicates that poorly written drivers or drivers that don't get in and out of their routines quickly enough are to blame.
I've disabled all non-essential devices in the BIOS (e.g. parallel port, 1394 port, serial ports, etc) and the problem persists. If I could attach a kernel tracer in XP 64, I could probably track down the guilty driver but apparently XP 64 is not really supported by Microsoft's kernel tracing tools. The only thing I'm left with is to start playing a game of elimination by disabling drivers via Device Manager and see if it stops - hopefully without accidentally locking myself by inadvertently disabling a core driver. Or maybe get my company to permit a Win7 64-bit loadout and see what happens.
This machine is killing me and is eating at least an hour of my time every day trying to figure this problem out. :emotion-41:
Does anyone else happen to have any insights on what else to do at this stage?
Thanks
Mark
M. Ingersoll
6 Posts
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June 24th, 2011 06:00
UPDATE - Traced at least one source of my problems down to a Solid State Disk that's been added as a second drive. It's a Kingston SSDNow 256GB. Whenever there is substantial disk I/O with this disk, I get high DPC's. I don't for the spinning disk (Hitachi 7200 rpm, 250GB disk). Looking further at this, it seems the BIOS has assigned the SSD to PIO mode whereas the spinning disk is "Ultra DMA Mode 5". Since this is a laptop, I don't have the ability to wire the SSD into another SATA/IDE port. I switched the two disks around and the problem remains.
The BIOS doesn't seem to allow me any way to force this channel to use a DMA mode, and it also seems to be causal to the poor I/O performance I'm observing. [sigh]
speedstep
9 Legend
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47K Posts
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June 24th, 2011 07:00
Windows will automatically switch a drive to PIO after multiple failures reading.
M. Ingersoll
6 Posts
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June 25th, 2011 04:00
I removed the SSD, deleted the drivers to force Win XP to re-install them (which it did nicely) and sadly, this wasn't the issue. Now that the SSD is out of the picture, the DPC storms are still around. At the moment, this laptop is unusable and it's not even a month old.
BTW, the DPC's should look something like this (which I'm told is actually on the poor side of nominal).
And my laptop looks like this for the first 15 minutes of life after bootup, presumably driven by some disk activity.
Unless I come across any viable options, I think we're going to have to do a complete OS re-install, check DPC's and only initialize/update the drivers one at a time until we can figure out what's happening.
M. Ingersoll
6 Posts
0
July 3rd, 2011 17:00
UPDATE - 7/3/2011 - If I move the hard disk over to the other drive slot, the problem disappears. Notably, when it sits in the primary drive slot, the IDE driver in XP sets the transfer mode to UDMA 5. Anything in the other slot - whether it be the primary hard disk or the SSD - it always sets the transfer mode to PIO. In combination with intermittently failing USB ports, I think the motherboard may have a fault. The primary hard disk can sit in either drive bay and boot from either, but in the secondary drive bay - it always drops down to PIO mode and results in the above DPC storm. Also, in this configuration a bootup and login takes 15 minutes. My conclusion is the motherboard is either bad or for some reason, the XP drivers and this board don't work well for the secondary drive bay.
I ended up buying a SATA to USB cable, connected this to my SSD and wow, the data flies back and forth nicely.
M. Ingersoll
6 Posts
0
August 1st, 2011 05:00
UPDATE - 8/1/2011 - Changed out motherboard and the problem persists. I suspect this is a driver issue with XP 64-bit more so than a hardware issue. At this point, I'll probably upgrade to Windows 7 if my company permits it. If this gets squared away after that, I'll report back. [sigh]
mikeburroughsde
3 Posts
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September 8th, 2011 16:00
It (sadly) may not fix it. I'm currently on Windows 7 x64 on my 6500, and I've had this issue for quite a while, and all Dell has to say about it is "reinstall windows"
M. Ingersoll
6 Posts
0
September 8th, 2011 17:00
Thanks for that data point. About 2 weeks ago, we had Dell out to replace the motherboard again because of something else that failed on it. This time around, the USB ports on the right side of the laptop no longer work and upon boot up, an attached USB keyboard and mouse won't initialize (docked). I have to open up the laptop and select the boot profile manually (docked, undocked), close the lid and let it finish booting. After it gets to the Windows login screen, the kb and mouse will eventually initialize and come to life. This wasn't the case with the previous two motherboards, so it feels like we're just trading one problem for another.
I have not tried to install a disk into the second drive chassis, because when the Dell tech replaced the board this second time around, he ran off with the 2.5" SATA to motherboard connector (small plastic connector). We can't find the part number in any of the diagrams and Dell tech support acts stupified when we try to describe to them what exactly it is we need.
Upon receiving that adapter, I'm going to slide in a fresh boot disk and load Win 7 on it. If the laptop continues to exhibit the same drive channel problems, then I think we'll have to conclude there is a hard fault in there. To that end, we'll have to investigate our options on how to redress this with Dell given a clearly defective product.
Two other things to add. The last two Dell tech supports replaced the motherboard from packages that were labeled "refurbished". When I asked the Dell techs about it, they stated all they've ever seen were refurbished parts used for replacements. Two colleagues who are also experiencing a never ending series of problems mentioned to me they heard Dell was quietly trying to sell out all of their remaining M6500 inventory as they launch their M6600 line.
At this point, Dell's reputation is at an all-time low with me. It's like when Gateway used to provide outstanding PC's back in the 1990's, but "sold out" and started delivering crap until they drove the company into the ground.