Problem with high DPC latency on Windows 8

[Jason Voorhees]

I have just installed Windows 8 consumer preview in my computer and started using it. Since I am a software developer, I need to check DPC latency. The DPC latency is used to see the performance of the computer while transferring or processing the data in real time. Softwares which need to undertake multiple processes at same time need to have DPC latency of low rate. In Windows 8, the DPC latency is in range of 1000 μs while in Windows 7 and Windows XP it would be around 500 μs. Can someone explain me why such a large difference is occurring?

[aSITA]

As we know that hardware requirement for Windows 8 is higher than that of Windows 7 or Windows XP. To operate properly, Windows 8 needs to have a dedicated graphic processor while Windows 7 used to work on integrated graphic processor easily. I checked the DPC latency in my computer which is inbuilt in Windows 8 and I found that Nvidia graphic drivers are using most of the DPC latency to operate. This result was given to me by DPC Latency Checker v1.2. You can check it on your computer too.

[ZAHAR]

Windows 8 consumer preview is like a trial version of the main operating system that will be released later on. I think that consumer preview must not have proper design due to which the DPC latency is very high in your computer. You can make a small report out of it and submit it to Microsoft. They will surely look into the matter and tell you if it is proper or not. Since consumer preview is not the complete version and it is provided just for demonstration, I think that Microsoft might not have fixed the excess DPC latency that is seen to you. All we can do is to wait and see if any changes in main release version of Windows 8 have been made.

[Phalguni88]

I don’t think that the problem of high DPC latency should occur in Windows 8 consumer preview. The kernel used for maintaining the DPC latency in Windows 8 consumer preview is same as that of Windows 7. So I don’t think there must be any difference in the readings. As mentioned by aSITA in her post above, the increase in hardware requirement will not affect much.

You will only see increment of 50 μs to 100 μs in the readings of DPC latency in Windows 8 as compared to that of Windows 7. I think that it must be something to do with consumer preview.

[Clarice]

I studied the DPC latency in Windows 7 and Windows 8 developer’s preview and I think that there is nothing wrong with the kernel that will maintain the DPC latency in Windows 8. It is the utility that displays the DPC latency is showing you wrong information.

I don’t think that this problem will be existing in the main release of Windows 8. So you can just relax and wait till the main version of Windows 8 is released and then you can work on projects that need to have less DPC latency.