Discussion: NVIDIA Display Driver (nvlddmkm.sys) DPC Latency

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What a "good" DPC during load PC?
frame rates always 60 - then stutеer - drop to ~30 for 1 sec - then again 60
This is 100% due to having Vsync enabled. It artificially caps your frame rates at your monitor's refresh rate, which in your case is 60. Then whenever it fails to render 60 frames in time, it will drop down to the next tier (I'm at a loss for the right word, it has a specific name), and that is 30 frames per second.

If your computer can barely handle running the game at 60 fps consistantly, it will repeatedly switch between 30 and 60 fps depending on the scenes being rendered. If you stare at the sky for example you'll probably always be at 60, but stare at a heavy action scene and it probably remains at 30.
 
By the way, did you use this method to measure ISR and DPC?
He was recommended to me as a replacement for LatencyMon
 
I hope the 8-pin splits to two separate tiers on the power supply?
Let's not worry about that, since it's not relevant to this thread. Vsync is for sure that person's issue, and neither vsync or power supplies is the cause of the Nvidia issue. There's just been way too much cross-talk in this thread lately, this thread was posted in July, and yet the majority of all the comments have come from December. They are accruing faster than I can dispel misinformation at this point.
 
By the way, did you use this method to measure ISR and DPC?
Try it if you want, it's just a much more complicated way to get similar data, and is presented in a fashion that is WAY more difficult to read and use than LatencyMon.
 
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I hope the 8-pin splits to two separate tiers on the power supply?
6+2 in video card, in PSU just 8 pin.
Let's not worry about that, since it's not relevant to this thread. Vsync is for sure that person's issue, and neither vsync or power supplies is the cause of the Nvidia issue. There's just been way too much cross-talk in this thread lately, this thread was posted in July, and yet the majority of all the comments have come from December. They are accruing faster than I can dispel misinformation at this point.
Okay, let's not talk about that anymore.
Then my last request
Can someone post their LatencyMon results, when you open websites in a browser, open applications, etc.
And during the load on the computer, so that I can compare with my own, please.
 
6+2 in video card, in PSU just 8 pin.

Okay, let's not talk about that anymore.
Then my last request
Can someone post their LatencyMon results, when you open websites in a browser, open applications, etc.
And during the load on the computer, so that I can compare with my own, please.

If you read back through the thread i have already......

post #171
 
Если вы перечитаете ветку, я уже ....

пост №171
Hmm, you have significantly less readings with the same actions as me.
My results can be seen on the second screenshot, there are several drivers strongly over 500+
Does this mean I have a problem?
I never got to the end, to be honest.
 
Here is my LatencyMon result while playing Cyberpunk 2077.
It did not change after 5 or more minutes btw.
 

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Hmm, you have significantly less readings with the same actions as me.
My results can be seen on the second screenshot, there are several drivers strongly over 500+
Does this mean I have a problem?
I never got to the end, to be honest.

are all your drivers up to date ? and i mean ALL as in device monitor too, because a classpnp.sys spike can be commonly attributed to missing drivers in some cases
 
are all your drivers up to date ? and i mean ALL as in device monitor too, because a classpnp.sys spike can be commonly attributed to missing drivers in some cases
It is very difficult to understand the latest version of them or not, because most of them were provided by Microsoft with the date 2005-2016
On the website of the manufacturer of the motherboard, what it offers, I installed it (besides the network one, I recently updated it)
 
It is very difficult to understand the latest version of them or not, because most of them were provided by Microsoft with the date 2005-2016
On the website of the manufacturer of the motherboard, what it offers, I installed it (besides the network one, I recently updated it)

go to the motherboard manufacturers site and download the latest drivers for your specific motherboard from there. try those first
 
I'll hereby share my final settings and DPC latency test results. At this point I am convinced that there's not much we can do to completely eliminate DPC latency spikes. Even on properly configured and up-to-date machines the issue persists due to it being a Nvidia driver issue.

So I've tried to mitigate the issue as best as possible. I'll summarize what I've done:

Right now I've been able to achieve DPC execution times in the range of 0 to 64 μs (99,77% of total) with the sporadic spikes in the range of 256 to 512 μs (0,03%), which for me is acceptable.

I've applied the following tweaks:

1. Used the Microsoft Interrupt Affinity Tool to assign the Nvidia GPU to the least busy CPU core, which in my case is CPU 4. This way there is less competition on Core 0, which handles the majority of DPC's

2. Applied several settings to lower latency caused by the Realtek Network Interface Controller (I've used this guide)

3. Plugged my mouse and keyboard to the USB Controller that is directly connected to the CPU (and not the chipset) to reduce input lag. (don't know if this is useful regarding DPC latency, but i'll mention it anyway)

4. I've set the interrupt priority to high for the GPU and the USB controller (where the mouse and keyboard are plugged in) using the MSI mode utility (discussed here) to give the Nvidia GPU and USB controller for the mouse and keyboard priority.

1672847229505.png

As for the final results:

5 minute run using LatencyMon:

1672846221605.png

Total DPC execution times measured using the Windows Performance Toolkit (xperf). I've used this guide.

Total DPC execution times.jpg

And more specific for the Nvidia Driver (527.56):

1672848109762.png

Driver execution times in LatencyMon before (first image) and after (second image) applying the tweaks:

1672848575825.png

1672848657927.png


My system feels very responsive now. No more audio drop-outs and pops and clicks. For now I'll leave it as it is. Hopefully this helps.

PC Type: Desktop
Operating System/Version: Windows 10 64-bit 21H2 (OS Build: 19044.2364)
Motherboard: MSI B450 Tomahawk (Non-MAX) (bios: 7C02v1I)
Processor: AMD Ryzen 7 5800x
Memory: G.Skill Ripjaws V 32GB 3600 MHz
Graphics: Nvidia RTX 3060 TI (Driver Version: 527.56)
Network Interface: Realtek PCIe GbE Family Controller (Driver version 10.62.824.2022)
Audio Interface: Focusrite Scarlett 8i6 (Driver 4.102.4)
Storage: M.2 SSD Samsung 970 Evo Plus 2TB
 
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I think you’re onto something regarding the NIC’s.

On my end, other than the awful pops, crackles etc. I noticed that most games that would bring my PC to load would crash pretty quickly afterwards. I noticed this with Horizon Zero Dawn, and Batman Arkham Origins, both of which crash within 5-10 mins of play.

So after continual fiddling with the MSI and Interrupts, I decided to go into the BIOS and change a few more things.

Heeding garlin‘s remark about the NIC, I disabled onboard lan on my Aorus b550i AX Pro WiFi, as well as WOL, and set the PCIE to Gen 3.

Since doing this, audio has been fine, system feels a lot more robust, and both games mention work fine, tested a couple hours apiece with no crashes.

Thanks for the heads up, and hope this might help someone!

My system:

Aorus B550i AX Pro WiFi
Ryzen 7 5800X
32GB RAM
1TB Samsung 980 Pro M.2 NVMe
Nvidia 3060ti Founders Edition

Hi All,

Just to add to my original post above, I hadn't tested out LatencyMon as my machine had been running stable ever since, howeve yesterday I attempted to give it a go.

I have set checked the MSI setting for my GFX specifically, set it to high, and ensured the interrupt is on a different core for this too (set to CPU 6 which appears to be the one with the least activity spikes).

If I leave the system idle for 5 mins with it running, then the DPC spike remains between 150 - 500, however the moment I open the browser, play some YouTube, or have Steam running in the background, then the DPC spike from nvlddmkm.sys spikes to around 1500, and then further to 2500. At this point, the system is still rock solid, and I still no longer experience poor audio/pops/crackles or general instability or crashes.

I'm also running the latest Nvidia drivers updated directly from the GeForce Experience app.

As someone else has surmised earlier in this thread somewhere, this issue is probably prevalent with many people, but just goes unnoticed, because it is still possible to have a system that appears robust, but still exhibits these spikes through LatencyMon.
 
Hello. I am lost, and I beg you for help!
I have a Dell Xps 8959 (i7 12700K, Rtx 3070 , 32 gb Ram)
I noticed some cracks on the sound occasionally.
Dell suggested me to replace the motherboard.
Anyway, doing my research, i found latencymon and the values are extremely high
Screenshot_3.png

Screenshot_4.pngScreenshot_5.png

Any help? Suggestions?
I m not so sure that replacing th motherboard will fix the issue.
 
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MODERATOR NOTE:

Welcome to our new visitors, just a quick reminder. We've had an outpouring of feedback, but now after 31 pages -- it's time to get MORE FOCUSED on new comments. Specifically, we're looking for cases where users made noticeable improvements to DPC latency, or stability.

Not to pick on anyone, but we're not here to share "me too!" stories. Everyone knows DPC's broken on NVIDIA/"gaming" PC's!

The goal moving forward is to find patterns in success stories. We have enough stories of XYZ did not work for me. Hopefully, some of the success stories will help other users improve their setups.

Because this thread's getting long, as Mod, newer posts which don't fit "this worked for me" will be trimmed. Yes, DPC is a frustrating topic, but we'll get there faster if we streamline the responses.

DON'T FORGET: BE MORE SPECIFIC. Share your Windows patch level (19045.xxxx), driver version, etc. You don't have to post every LatencyMon graph if your latency numbers look terrible. There's always someone who has a PC worse than you.
 
Update for anyone that might be waiting on me, with a TLDR at the bottom:

I spent all week working on a comprehensive, general DPC latency guide. It's taking longer than planned, and part of that is because it's a hefty thing to tackle, so it's been a ton of work, but also I'm having a lot of real world responsibilities interfering. The goal of the guide is to hopefully be able to take the majority of all computers and get them into good/acceptable DPC ranges, no matter how bad their spikes are, and I'm confident that it is doable.

This not only improves the performance of those machines so that they play games and do audio production better, but then all of the people that have general DPC problems will be able to participate in this Nvidia thread, since they won't be fighting other DPC issues simultaneously, which has only confounded the troubleshooting of the Nvidia bug. This thread has inadvertantly revealed that the Nvidia bug is the least of many people's problems, as their other DPC issues are so bad that some of those computers aren't usable.

After this guide is up, there's quite a few ideas I still want to try out for the Nvidia bug, some of which I have high hopes for. In the meantime, the best thing we can do to get a solution for this bug is to have everyone contact all of their favorite gaming YouTubers, and gaming news sites they frequent, and see if any of them will run this story. It just needs some news coverage and it will force Nvidia's hand, as that's how many other similar issues get fixed. This issue is big enough that is warrants it too, especially since the data shows it's been going on for years, and a huge number of people are affected. Googling nvlddmkm has almost half a million results, and that's not all of the terms you could use either.

I still think *every* Nvidia user is affected, it's just that on fairly optimized machines it's not as noticeable, as there has yet to be a single person to show a fresh install of any operating system from Vista through Windows 11 (unmodified) where nvlddmkm is less than 100. On the other hand, I switched over to XP SP3 recently for testing, and Nvidia never spiked above 50 on that, which I expected because I never had issues on my gaming rig, which was running XP until the end of the year 2021. This has to be a bug that started in Vista or W7 and progressively got worse over time, as other drivers became more demanding, such as ntoskrnl which interact negatively with Nvidia.

Anyway, please read everything Garlin said in the post above, and also go read all the links on page #1 of my original post. At this point, unless you have solutions that you tested thoroughly and can provide proof with before/after screenshots and exact step by step on how to fix it, then we just don't need any more posts in this thread. At this rate we'll reach over 100 pages by the start of March because there's way too much nonsense posting.

TLDR: The point of this thread was to troubleshoot the *Nvidia* driver bug, not all of the mundane DPC issues that everyone has. There are solutions all over the internet for those problems already. The Nvidia bug is special because it has no solutions, anywhere. That's what this thread is for, is to finally take this bug seriously and fix it. In the meantime, if you are someone that is struggling with non-Nvidia DPC problems, wait for me to post my all-in-one fix everything DPC guide and I can almost guarantee it will fix the majority of everyone's non-Nvidia DPC issues if you follow that guide correctly. I planned to post it yesterday or today, but real world interferences are slowing me down. I still have a job, family, etcetera that I have to take care of and those come first, so please be patient.
 
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