DPC Latency issue

Hi all,

My computer was running fine yesterday. Last night I installed the game FLY'N using Steam and also installed the latest Windows Update at the same time. I noticed the opening video on FLY'N was slow and the sound was crackling/popping. Later, I noticed other games that worked fine before (League of Legends, Skyrim) doing the same thing (crackling audio, low FPS). Even in a fairly simple game I have called Intrusion 2, everything moves sluggishly now.

I uninstalled FLY'N and used System Restore to go to the point before the Windows Update, but I still have the same problems. I reinstalled my Realtek Audio Drivers (another website recommended it to solve the audio crackling problem on Windows 7), but no difference.

I read something about DPC Latency and conflicts in drivers. I downloaded LatencyMon and it did indeed say I have a problem. I've been searching for hours, but now I'm stuck and don't know the next step. So I copied the LatencyMon information below.

My motherboard/CPU are quite old, and I was thinking of getting new ones, but with everything working fine yesterday (including games like Skyrim) I was hoping to get another year or so out of it. Any help would be greatly appreciated.

Many thanks for reading and any suggestions you may have.

Best Wishes,
Patrick



I attached 3 screenshots from LatencyMon, sorted by Total Execution (ms).
1. just using LatencyMon & Firefox
2. after opening League of Legends and the Steam store window
3. after opening Skyrim

Stats from LatencyMon (after opening League of Legends and Skyrim)
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CONCLUSION
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Your system appears to be having trouble handling real-time audio and other tasks. You are likely to experience buffer underruns appearing as drop outs, clicks or pops. One or more DPC routines that belong to a driver running in your system appear to be executing for too long. Also one or more ISR routines that belong to a driver running in your system appear to be executing for too long. One problem may be related to power management, disable CPU throttling settings in Control Panel and BIOS setup. Check for BIOS updates.
LatencyMon has been analyzing your system for 0:01:16 (h:mm:ss) on all processors.


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SYSTEM INFORMATION
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Computer name: PC1
OS version: Windows 7 Service Pack 1, 6.1, build: 7601 (x64)
Hardware: Prime Series, ThirdWave Corporation, ECS, G33T_M
CPU: GenuineIntel Intel(R) Core(TM)2 Duo CPU E6850 @ 3.00GHz
Logical processors: 2
Processor groups: 1
RAM: 3071 MB total


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CPU SPEED
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Reported CPU speed: 2992.0 MHz
Measured CPU speed: 2974.0 MHz (approx.)

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.


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MEASURED INTERRUPT TO USER PROCESS LATENCIES
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The interrupt to process latency reflects the measured interval that a usermode process needed to respond to a hardware request from the moment the interrupt service routine started execution. This includes the scheduling and execution of a DPC routine, the signaling of an event and the waking up of a usermode thread from an idle wait state in response to that event.

Highest measured interrupt to process latency (µs): 49074.038272
Average measured interrupt to process latency (µs): 71.946133

Highest measured interrupt to DPC latency (µs): 30448.727271
Average measured interrupt to DPC latency (µs): 58.807401


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MEASURED SMI, IPI AND CPU STALLS
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The SMI, IPI and CPU stalls value represents the highest measured interval that a CPU did not respond while having its maskable interrupts disabled.

Highest measured SMI or CPU stall (µs) 0.342182


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REPORTED ISRs
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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): 50245.881016
Driver with highest ISR routine execution time: dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation

Highest reported total ISR routine time (%): 25.400621
Driver with highest ISR total time: dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation

Total time spent in ISRs (%) 39.690579

ISR count (execution time <250 µs): 215489
ISR count (execution time 250-500 µs): 0
ISR count (execution time 500-999 µs): 1770
ISR count (execution time 1000-1999 µs): 1733
ISR count (execution time 2000-3999 µs): 3683
ISR count (execution time >=4000 µs): 0


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REPORTED DPCs
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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): 45309.714906
Driver with highest DPC routine execution time: ataport.SYS - ATAPI Driver Extension, Microsoft Corporation

Highest reported total DPC routine time (%): 3.413558
Driver with highest DPC total execution time: nvlddmkm.sys - NVIDIA Windows Kernel Mode Driver, Version 320.49 , NVIDIA Corporation

Total time spent in DPCs (%) 7.989972

DPC count (execution time <250 µs): 251075
DPC count (execution time 250-500 µs): 0
DPC count (execution time 500-999 µs): 331
DPC count (execution time 1000-1999 µs): 168
DPC count (execution time 2000-3999 µs): 744
DPC count (execution time >=4000 µs): 0


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REPORTED HARD PAGEFAULTS
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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.

NOTE: some processes were hit by hard pagefaults. If these were programs producing audio, they are likely to interrupt the audio stream resulting in dropouts, clicks and pops. Check the Processes tab to see which programs were hit.

Process with highest pagefault count: msmpeng.exe

Total number of hard pagefaults 467
Hard pagefault count of hardest hit process: 419
Highest hard pagefault resolution time (µs): 177197.712233
Total time spent in hard pagefaults (%): 1.551692
Number of processes hit: 10


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PER CPU DATA
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CPU 0 Interrupt cycle time (s): 39.596940
CPU 0 ISR highest execution time (µs): 49440.167447
CPU 0 ISR total execution time (s): 35.238458
CPU 0 ISR count: 151968
CPU 0 DPC highest execution time (µs): 45309.714906
CPU 0 DPC total execution time (s): 6.043290
CPU 0 DPC count: 214289
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CPU 1 Interrupt cycle time (s): 30.333597
CPU 1 ISR highest execution time (µs): 50245.881016
CPU 1 ISR total execution time (s): 25.128532
CPU 1 ISR count: 74602
CPU 1 DPC highest execution time (µs): 31446.836230
CPU 1 DPC total execution time (s): 6.108978
CPU 1 DPC count: 38933
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