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rcollings replied to MagicAndre1981's topic in Windows Tips 'n' TweaksHi Andre - thanks for prompt rely. Had rerun the trace for a shorter period when the DPC was already in progress and captured a trace without the error. Here is the resulting display: which is not dramatically differnt to the first one So its something to do with my usb devices/drivers? In answer to your question about USB devices - I have lots: external drives, sound cards, graphics tablets, mice, printers, etc, etc. Its a Dell Latitude D820 laptop. Early on the process, when it looked like it might be the USB devices, I pulled out the two USB cables that connect to two hubs that connect most of my devices. The high CPU usage did not go away immediately so I assumed that it wasn't anything to do with USB. However.... 1) Does disconnecting the device remove the driver? Or to put it another way, if I disconnect a device and the problem doesn't go away immediately, can I assume that that that device and driver are not the cause of the problem? 2) I think the laptop has a number of devices that are connected internally via USB. I am not sure how I identify these. Incidentally, as far as I am aware, this is a new problem on an existing machine which did not have the problem before. As far as I am aware, I have not installed any new devices recently Can you suggest some next steps to try and track the problem down. I have uploaded the trace file here: trace file Many thanks for your help (and for your guidelines) Update: problem resolved. Turns out it was an external Creative USB Sound card. I went back and pulled out all the USB cables and this time I was specifically monitoring the processor usage by the DPCs rather than just looking at the overall CPU usage. As before the overall CPU usage remained high but the DPC usage dropped to zero. And then it was just a question of trying each device in turn until I found the one that restarted the DPC usage. Kicking myself now for not being more thorough in my my original testing - could have saved myself several hours. But your diagnostic tools pointed me firmly back at it being a USB device somewhere so we got there in the end. I was close to going out an buying a new machine - which I do need - but I can do so in a more measured fashion. Many thanks Richard Richard
rcollings replied to MagicAndre1981's topic in Windows Tips 'n' TweaksHi MagicAndre (and everybody else) - I wonder whether you could help with my problem I am having a problem with high CPU usage by DPCs. The problem is intermittent. It doesn't happen when the machine is idle but kicks in after a period of use and as I start to use more programs. It will go on for 5-10 mins and will some time stop by itself. It usually stops if I close down a few programs. It is not tied to any one program as far as I can see. I have followed your diagnostic procedure (I think - not being a developer, I am not an expert in these matters). The first problem I had was that I got a message saying "Session NT Kernal logger lost 2267 event" and that I need to increase the buffer size and/or number of buffers. Is this a problem and if so, how do I do this) Secondly, when I get the graph, there is only activity for the first 10s and only a few percent of the CPU. I ran the logging process for a lot longer than this and the high CPU usage only kicked in after a while Anyway, I selected the area where there was some activity and ran the analysis. Here's what I got: Is this any good? What does it mean? And what should I do next? Many thanks for your help (in advance!)