LatencyMon Result

[feelingcold21]

hello guys did a latency test when i played games,are these normals results?

https://imgur.com/EMUoJmM

View: https://imgur.com/EMUoJmM

 

[Colif]

what are specs of the PC?

The advice here might help

normal would show no problem in the top description area.

 

[ubuysa]

The two drivers that LatencyMon is highlighting there are WDF01000.sys and CLASSPNP.sys, but it's highlighting different aspects of these drivers.

The ISR execution time is the time that the Interrupt Service Routine is running. This is the front-end of device interrupts, the ISR gets control as soon the device raises an interrupt. The ISR code is part of the driver and it's designed to run for as short a time as possible. Typically, it just marks the I/O operation as complete, stores the buffer address, and then schedules a DPC to run later. Control is then given back to the running program (the game, audio player, browser, etc.). Generally ISRs cause few problems because they execute for such a short time.

The WDF01000.sys driver is the high-level Windows Driver Foundation driver, it will call other third-party drivers (that we don't see here) to run the ISR code in the specific driver. We have no other information here on what that third-party driver might be. You can see that the WDF01000.sys ISR is not the biggest contributor to the latency here so we can probably ignore this for now.

The DPC execution time is the time that the Deferred Procedure Call is running. This is the back-end of interrupt processing and handles most of the work in handling a device interrupt. If the ISR doesn't complete all the work needed for the specific I/O (which it rarely does) the ISR typically schedules a DPC to run later. DPCs are placed on a queue per processor and this queue is processed when the processor has no other useful work to do. Thus DPCs do not directly impact running work. However, whilst the DPC queue is running no other work can run on that processor so it's important that no DPC run for too long and that collectively the DPC queue doesn't run for too long. Long running DPCs are the usual cause for poor latency, just because they are the longerst running part of interrupt processing. In the case here you can see that the CLASSPNP.sys DPC execution time makes up most of the delay, so this is where you need to look first.

The CLASSPNP.sys driver is the high level PnP storage driver (although it can be involved with internal storage device as well), it will call other drivers (mostly third-party) to run the DPC code in the specific driver. We have no other information here on what the third-party driver may be, but if you have any external stroage drives attached that are actively in use then that's the place to start looking.

It might be simply a badly fragmented drive, it might be a third-party anti-malware product (it often is), it might be an iffy USB port or cable, it might even be a failing drive. If you can, unplug all external stroage drivers and run LatencyMon again.