Dell Latitude DPC Latency Issues

OK...never expected these results, but - with the video driver released today (ISV_R210394, version 76.88) my latency dropped from 10,000 to 355 ms.
It looks like this video driver is the reason, as I haven't changed ANYTHING else.

 

Hi

I took this screenshot of my latency and wanted to ask everyone if its normal? The red spikes came when I opened photoshop. All other graphic intensive (VLC, Video editor) cause spikes too.

Sami

 

I would assume that's normal Sami. My Compaq V5000 has a similar appearance.

I only wish my e6400 looked like that instead of the solid 9ms with occasional spikes.

I tried disabling and re-enabling devices and I found nothing to help. I did disable eSATA in the bios and that made no change either. I'm still working with a relatively fresh install of Vista 64 so I'm thinking about changing from ACHI to ATA and see if that makes a difference.

 

Cool, I tried disabling a lot of stuff as well and nothing seemed to do much difference. Only thing I noticed if I detached the DVD from the media bay the spikes went through the roof.

 

The Latency Issue on my E6400 disappeared completely. Don't know exactly what is resonsible for that. Maybe you'll take a look on my post in some other thread around here.

 

No audio or video stuttering, but I still get latency spikes.

http://dingo9.net/faultybtwifion.jpg

I reverted to 7.2(A02) Intel Matrix Storage release, ans I toyed with the wireless. I found:

(off = disabled or not present in Device Manager, on = enabled in Device Manager)

Switch off:
BT off/Wifi on = no latency spike
BT off/Wifi off = no latency spike

Switch on:
BT off/Wifi off= no latency spike
BT on/Wifi on = LATENCY SPIKE
BT off/Wifi on = LATENCY SPIKE
BT on/Wifi off = no latency spike

It seems the spike only shows up when the Wi-Fi is on .. so I'm almost positive it's to blame.

Just for laughs, I uninstalled the Dell Wireless 1397 and used a 3Com PCMCIA Wi-Fi card, and there was no latency spikes there either. Is there a driver out there that seems to behave better in Vista 64 I should try out?

ALL EDITS COMBINED IN ONE:
Wi-Fi seems to be a contributing factor, but not the only thing behind DPC latency.

The random ~4000us spikes every 2-6 minutes identified to be caused by eSATA. Disabling eSATA removed these, as well as enabling and attaching a drive also eliminated these. So perhaps its the controller polling the eSATA port for the presence of the drive? I suppose the moral of this one is leave the eSATA port disabled until you actually need it.

I turned the Wi-Fi on and I get ~4000us reds every 60-70 seconds. and 30,000us+ spikes every other spike.

I turned off the Wi-Fi and I'm still getting 16,000us+ spikes every 8-10 minutes. This one's going to be tricky to track down.

 

krhainos - I have the Intel Wireless, not Dell, so I can't say that the wireless isn't also causing an issue. (On the other threads, I have seen several mentions that the Intel card seems to cause less issues regarding latency than the Dell cards.)

I can relate exactly to what you found with removing the optical drive. Could you possibly switch to regular ATA mode in the BIOS (instead of AHCI or IRRT) and see if that fixes things? If so, then it seems to be the same issue and work-around that I found. Also, either way, please make sure you report these issues to both Dell and Intel.

 

Interesting. I'm running AHCI right now -- I'll try going to ATA mode, see if that does anything.

EDIT:

I don't have my Vista 64 disc on me to repair the bootstrap when I switch from AHCI to ATA and such

 

which one is the esata device in the device manager? I cant seem to find it...

Is it this one: Intel(R) ICH9M/M-E 2 port Serial ATA storage controller -2 29D2?

 

If you have no eSATA device attached, you liekly won't see a device. You disable the eSATA capability inside BIOS.