A very newbie doubt about DPC Latency

Joined
Jul 21, 2017
Posts
5
Location
Mexico City
Hello everyone.

First of all, I want to address that I am not exactly what you would call a computer whiz, I know how to do some basic tuning stuff, but my knowledge is pretty much that.

Second, I also want to apologize in advance for how amateur and newbie this post might sound to all of you.

That cleared out, recently I bought a new PC (a relative did the building for me) and I have been wondering about DPC latency issues, since my last computer (8 years old to this day) used to have a terrible latency problem caused by an already veteran Nvidia GPU.

This computer usually fluctuates between 100 μs and 450-480 μs with the highest spikes caused by either nvlddmkm.sys, tcpip.sys, ndis.sys or dxgkrnl.sys. So, yes, I discussed this with a friend of mine who told me that, by today standards having that latency most of the time is considered in the really good side of performance. However, I suffer from a severe case of Obsessive-compulsive disorder that forces me to keep Latencymon open during long periods of time to see if I can catch a high spike. They are rare, however.

Yesterday I got two red spikes that went above 17.2 μs, both of which happened while I was playing different videogames. The first time I did notice the random "pop" into the game's music and I instantly Ctrl + tab to the desk to find the spike registered on Latencymon. The next one, I don't even recall noticing the crackling noise, I found the spike during one of my random "You gotta Ctrl + tab to check on it".

My question is: having an apparently isolated red spike on Latencymon that isn't followed by more computer lagging and sound-failures shouldn't be considered bad, should it? I ask this because the same friend I mentioned told me I was just thinking too much into it and letting anxiety take over and that, for a computer used mainly for playing games and idle internet browsing, it was doing just perfect. As I type, I am checking the latency fluctuates between 100 μs and 20 μs.

So, should I just simply uninstall Latencymon and enjoy the computer or should I do some other tweaks to keep my OCD pleased?

Thank you so much for reading!

Anna.
 
Hi. . .

The first question that I would ask - are you having problems with your system?

I would recommend that you update video, audio, wifi and Ethernet drivers - if updated ones are available.

Do so by going into Device Manager (devmgmt.msc), expand the appropriate section, 2x-click on the device, click on "driver" tab. This will give you the driver name (e.g., abc123.sys). Look it up in the DRT --> Driver Reference Table

Also be sure to check your system manufacturer's support site for driver updates. DO NOT rely on Windows to find drivers for you because it will always (99/.99%) tell you that your drivers are up to date.

Be sure to check for an updated BIOS.

If you have an Internet Security Suite installed - remove it with the appropriate removal tool, if available -

Uninstallers (removal tools) for common Windows antivirus software—ESET Knowledgebase

Regards. . .

jcgriff2
 
Hello, thank you for your quick response!

1) To be quite honest, I don't really think my system is having any issues at all, beyond what my OCD induced paranoia makes me think.

2) I will start updating the drivers as you told me:


  • My realtek audio drivers were updated a month ago when I got the puter and they are up to date as far as I can tell.

3) While trying to check on the drivers, just as you told me, I get the following scene:

Snapshot 1.png

I suppose, in the case of my ethernet driver, that the file I should update is e1d65x64.sys right? (Forgot to add: my system is in Spanish, so driver = controlador)

4) Regarding to BIOS, I am not very sure how to look for updates, nor if I could damage the system if I tried to.

5) I only have Windows Defender. To be honest, this is the first time I hear about an Internet Security Suite.
 
I suppose, in the case of my ethernet driver, that the file I should update is e1d65x64.sys right? (Forgot to add: my system is in Spanish, so driver = controlador)

You are correct - that is the only driver out of the files listed that you would need to look for an update for.

4) Regarding to BIOS, I am not very sure how to look for updates, nor if I could damage the system if I tried to.
For BIOS updates, always go to your system manufacturer's support site. If they list nothing, then you're fine.

If your system was custom built, you would need to go to the motherboard's manufacturer support site to check for updates.

Regards. . .

jcgriff2
 
Hello!


Yesterday I spent the evening updating drivers and such.

1) As for the graphic driver, I had to uninstall the most recent update and revert to the one I had, it made me get random spikes about 5,000 μs even when the computer was idle (around one every five minutes). With the current one, I'll get a random huge spike from time to time, but it's isolated and apparently not followed by more big spikes.

2) I updated the Ethernet driver and all the other devices that appeared below the Intel(R) Ethernet Connection (2) I219-V are nowhere to be seen as in the picture I posted in my previus post. Picture below.

Snapshot 2.png

Regarding the Intel update, it seems to have lowered the latency a little bit, however, Ndis.sys and Tcpip.sys sometimes still go up to 200 μs in Latencymon's "Highest reported DPC routine execution time" from time to time, yet I was told that is normal because I have an active connection.

3) Audio drivers were up to date, I don't notice any noticeable change with previous or new drivers.

4) I don't think I have a Wifi driver, so, that must be out of the question.

I add a latencymon screen cap, as well as the reads on the stats section.

Snapshot latmon 1.png

Snapshot latmon 2.png

Latmon stats:

CONCLUSION
_________________________________________________________________________________________________________
Your system appears to be suitable for handling real-time audio and other tasks without dropouts.
LatencyMon has been analyzing your system for 0:12:51 (h:mm:ss) on all processors.


_________________________________________________________________________________________________________
SYSTEM INFORMATION
_________________________________________________________________________________________________________
Computer name: DESKTOP-BKLIHOD
OS version: Windows 10 , 10.0, build: 15063 (x64)
Hardware: ASRock, B250M Pro4
CPU: GenuineIntel Intel(R) Core(TM) i5-6400 CPU @ 2.70GHz
Logical processors: 4
Processor groups: 1
RAM: 8155 MB total


_________________________________________________________________________________________________________
CPU SPEED
_________________________________________________________________________________________________________
Reported CPU speed: 2712 MHz

Note: reported execution times may be calculated based on a fixed reported CPU speed. Disable variable speed settings like Intel Speed Step and AMD Cool N Quiet in the BIOS setup for more accurate results.


_________________________________________________________________________________________________________
MEASURED INTERRUPT TO DPC LATENCIES
_________________________________________________________________________________________________________
The interrupt to DPC latency reflects the measured interval in which a DPC could execute in response to a hardware request from the moment the interrupt service routine started execution.

Highest measured interrupt to DPC latency (µs): 276.766805
Average measured interrupt to DPC latency (µs): 2.460206


_________________________________________________________________________________________________________
REPORTED ISRs
_________________________________________________________________________________________________________
Interrupt service routines are routines installed by the OS and device drivers that execute in response to a hardware interrupt signal.

Highest ISR routine execution time (µs): 254.575221
Driver with highest ISR routine execution time: dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation

Highest reported total ISR routine time (%): 0.109743
Driver with highest ISR total time: dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation

Total time spent in ISRs (%) 0.12650

ISR count (execution time <250 µs): 205587
ISR count (execution time 250-500 µs): 0
ISR count (execution time 500-999 µs): 1
ISR count (execution time 1000-1999 µs): 0
ISR count (execution time 2000-3999 µs): 0
ISR count (execution time >=4000 µs): 0


_________________________________________________________________________________________________________
REPORTED DPCs
_________________________________________________________________________________________________________
DPC routines are part of the interrupt servicing dispatch mechanism and disable the possibility for a process to utilize the CPU while it is interrupted until the DPC has finished execution.

Highest DPC routine execution time (µs): 422.694690
Driver with highest DPC routine execution time: nvlddmkm.sys - NVIDIA Windows Kernel Mode Driver, Version 382.53 , NVIDIA Corporation

Highest reported total DPC routine time (%): 0.039954
Driver with highest DPC total execution time: nvlddmkm.sys - NVIDIA Windows Kernel Mode Driver, Version 382.53 , NVIDIA Corporation

Total time spent in DPCs (%) 0.187787

DPC count (execution time <250 µs): 1701736
DPC count (execution time 250-500 µs): 0
DPC count (execution time 500-999 µs): 4
DPC count (execution time 1000-1999 µs): 0
DPC count (execution time 2000-3999 µs): 0
DPC count (execution time >=4000 µs): 0


_________________________________________________________________________________________________________
REPORTED HARD PAGEFAULTS
_________________________________________________________________________________________________________
Hard pagefaults are events that get triggered by making use of virtual memory that is not resident in RAM but backed by a memory mapped file on disk. The process of resolving the hard pagefault requires reading in the memory from disk while the process is interrupted and blocked from execution.


Process with highest pagefault count: none

Total number of hard pagefaults 0
Hard pagefault count of hardest hit process: 0
Highest hard pagefault resolution time (µs): 0.0
Total time spent in hard pagefaults (%): 0.0
Number of processes hit: 0


_________________________________________________________________________________________________________
PER CPU DATA
_________________________________________________________________________________________________________
CPU 0 Interrupt cycle time (s): 22.710586
CPU 0 ISR highest execution time (µs): 254.575221
CPU 0 ISR total execution time (s): 3.898332
CPU 0 ISR count: 205226
CPU 0 DPC highest execution time (µs): 422.694690
CPU 0 DPC total execution time (s): 5.407016
CPU 0 DPC count: 1665889
_________________________________________________________________________________________________________
CPU 1 Interrupt cycle time (s): 6.613273
CPU 1 ISR highest execution time (µs): 177.993363
CPU 1 ISR total execution time (s): 0.005452
CPU 1 ISR count: 360
CPU 1 DPC highest execution time (µs): 258.900442
CPU 1 DPC total execution time (s): 0.181660
CPU 1 DPC count: 17786
_________________________________________________________________________________________________________
CPU 2 Interrupt cycle time (s): 8.675371
CPU 2 ISR highest execution time (µs): 1.311209
CPU 2 ISR total execution time (s): 0.000002
CPU 2 ISR count: 2
CPU 2 DPC highest execution time (µs): 237.616888
CPU 2 DPC total execution time (s): 0.106194
CPU 2 DPC count: 9141
_________________________________________________________________________________________________________
CPU 3 Interrupt cycle time (s): 7.077754
CPU 3 ISR highest execution time (µs): 0.0
CPU 3 ISR total execution time (s): 0.0
CPU 3 ISR count: 0
CPU 3 DPC highest execution time (µs): 221.510693
CPU 3 DPC total execution time (s): 0.100237
CPU 3 DPC count: 8924
_________________________________________________________________________________________________________



My friend keeps insisting that I should either ditch the Nvidia card for an AMD one or that I learn to live with this, because it's normal. Do you think I am just overthinking way too much?


Thanks for your support so far!
 
Do not ditch NVIDIA for AMD/ATI -- if you do, you'll be asking for my help with BSODs!

I see 1 NVIDIA BSOD for every 100 AMD/ATI BSODs.

ATI driver writing leaves a lot to be desired.

Please refresh my memory - what is "I219-V"?

I wish I could help you more directly with the latency, but it is a subject that I don't know much about.
 
I'll follow your advice, then. I haven't dealt with BSOD's for three years and I prefer to stay like that LOL!

I219-V is what appears at the end of my Intel Ethernet device, I myself am not exactly sure what it means, it's just in the name.

It's not as if the latency was that bad, but I am kinda disappointed to have a brand new computer and face that DPC doesn't stay as low as possible, but I suppose that's normal if I am not perfecting my computer for audio, I think...

I read somewhere on the internet (My OCD forced me to) that while playing videogames, it's normal to have random spikes in latency as the load on the GPU goes further.

I still need to update the BIOS, gonna ask for help to do that.
 
Heyo, I've done everything you told me so far.

Usually, "current measured interrupt to latency" is around 45 to 90 μs and sometimes it goes up to 200.

"Highest reported ISR routine execution time" and "Highest reported DPC routine execution time" are around 400 to 800 μs when they spike, now the highest offender here is dxgkrnl.sys whenever the spikes reach the yellow or red point.

I must admit, it's really frustrating when things like this happen, lol, specially when the computer is new, makes you feel bummed that besides having "good" stuff in your hardware, software can still mess your specs.
 
If you believe it to be related to video, try several NVIDIA drivers, including beta versions, if available.
 

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