The sad Reality about High DPCs. Read On

hi guys!!! Today I bring something that has been discussed in MANY FORUMS, and no one seems to have an answer. I tried EVERYTHING and read as much as I could before posting here!!!! This is the situation:
I bought a new HPdv9500t laptop, with vista home 32. using DPC Latency Checker ( http://www.thesycon.de/deu/latency_check.shtml). It swhows spikes all the time. As it recommends, i tried disabling and enabling devices in device manager. I tried everything. Ever restarting after each change, just in case the drivers is still there. I even tried to disable all services that I could. Microsoft says that a good driver should not spend more that 100 us in an interruption. I get red spikes of 3000 us and more sometimes! I can't find any solution... I tried to run RATTV3 ( http://www.microsoft.com/whdc/DevTools/tools/RATT.mspx) to see what driver is the culprit. DCP doesnt show that, just the dpc times.
But RATT doesnt work on vista....
The funny thing just begins......
I decided to intall Windows XP ( I have both now. thanks Hackez and Mujjman). . The latency in DPC checker is EXTEMELY LOW!!!! the highes peak is around 50us, even with all hardware on!!!!
So...what can we think about this??? A looot of musicinas and 'real time' users complain, because their harware doesnt respond in vista. This is patetic!!! I know...I know...you will say..."Disable your Wlan, balbla". This is true...the WLAN makes a lot of spikes, but even with it off, i get a lot of them. The only time I got decent DPC in Vista was when I disabled EVERYTHING at the device manager (usbs, mem card read, fingerprint, nvidia, sound, FIREWIRE). but after enabling harware the problem comes back WITHOUT ANY LOGIC!!!! imposible to identify Any problematic hardware.
But this is the reality: I gave up and I think this problem is in the heart of VISTA, the way it treats hardware! It is not like "i have all disabled, and good DPC times, and as soon as i enable X device( the problematic) the dpcs go up".
People.....we all need to find an anser for this....you can check it yourself. looots of forums....no answers......Should I take VISTA from my laptop for ever?? DO the people from microsoft do product with low performance on purpose?

All your comments will be appreciatted. I aim to make this thread the thefinite SOLUTION/ Experience/ Knowledege base for this problem...

Thanks a lot!!!!

Danny Bullo

PS: Maybe it has nothing to do with this but....Thew ACPI INSIST on sharing IRQs on several devices! I know....we have sicussed this....it is the way it works...butthat sharing could hav a limit. Maybe the hards starst just to not tolerate that and this making high dpcs!!!!!

 

Hello Again!!!

Anyone?? Any answer??

Thanxs again...

Danny Bullo

 

Does it affect your performance? Because if not, I wouldn't care.

 

Never heard of it.

 

Guys:
Yes. It affects my performance:

1)raltimeapplications suck as audio recording/edition.
2) Even when I watch a DVD I can see a short drop out, when the image gets still for a short period of time. It happens every 10 seconds, the same time interval as the high DPC spike occurs.

3)google "high dpc latency". You will be surprised to find how many people are getting crazy about that, but more specifically in Vista!

Thanxs again!!!!
Any other thought? Someone in the 'realtime' world? in the 'drivers' world?



Danny Bullo

 

Had it on my vostro too. It caused the sound to skip.

 

Hey guys!!! Believe me...this is gonna be a big issuue in the near future!!!
Rememeber!

 

Maybe its a problem with your vista installation like to much preinstalled crap on it, outdated drivers or something.
Make a fresh install and download and install the latest drivers from the manufacturers homepage and run your test again.

I (and many other people) have no such problems with vista...

 

Welcome to Windows. If you have problems with latency, there's not a lot you can do. Windows isn't meant to run as a real-time OS, and it's a fundamental limitation of the operating system. If you want something that's tuned to give you predictable low-latency response, look at something like Medibuntu, a media-centric version of Ubuntu that comes with a low-latency kernel.

 

Pitabred be careful Bill Gates is spying on you! But anyway if true looks like back to XP for OP. Is Medibuntu going to have the kind of software OP will need?

 

hmmm, well you made me curious, so i tried the dpc latency checker. i have a HP 8510 P with xp 64. when i started the program, it showed me not some kind of spikes, but a steady high peak of 2900 us. the culprit was found in seconds. i tried disabling the wifi, that didn´t help.

but when i disabled the ethernet adapter the high peak was gone and the latency went down to 150 us.
thanks for the tip bullo.
+1

btw, it is an intel ethernet driver, that causes this high latency.

 

update

installed a new driver ( downloaded it from intel directly) and now the high dpc latency is gone even when i have the ethernet enabled. latency is still at around 150 us.

thanks for the hint.

 

I'm not paranoid I just know about both Windows and Linux at a sysadmin level, and know "bad" when I see it.

Anyway, it depends on what the OP needs. There are a number of very good audio apps available under Medibuntu, such as Audacity and the jack audio subsystem, and I haven't had an issue with DVD playing. But it depends on what you're trying to do.

There's also Ubuntu Studio, which is explicitly designed for pro-level sound recording and use, and from what I hear is much better than most Windows software, and is much better for the price.

 

thanxs guys....yeah..windows ins not mean to be a real time Os, however I have isntalled many audio machines with XP including all the 'audio tweaks'. It could be that hp install a lot of crap and the pre installed os is far from good.
i will try with a clean installation . As i said, the main culprit in theses cases is a poor written driver that couses momentary cpu hogs. The main concern was taht i tried disabling everything, including devices and services...with no luck....just google high dpc time or latency...you will see how many face this problem!
Thanxs again!!!

Danny Bulllo

 

schoko: Im glad you dolved it!!! YOu will be surprised to know that i have dual boot, vista and xp. Forgetting about the 'every 10 secs spikes', in vista I get around 110/160 us green bars. The same machine, with Xp, i have solid green bars around 20-40 us with all hardware on!!!!!!!
Billie, what is going on?????? Vista dealing bad with hardware at a low level?????