Hi,
I’m investigating a DPC CPU spike issue with lots of drivers / devices for high speed USB audio streaming.
When the devices are streaming from / to a Windows 7 or Windows Vista PC, one sees periodic DPC CPU spikes in the Windows Task Manager. Depending on the device, the spikes can use up to 100% CPU of one core for seconds. The spikes show up on both 32 and 64 bit Windows, but on the 64 bit versions they are typically spreaded amongst all cores. On Windows XP this problem does not exist, no spikes at all.
The driver that I am maintaining works with a continous Isoc reader that schedules 4 - 8 URBs of 8 packets (one per micro frame) with 512 byte capacity.
I’ve tried to remove all productive code which may delay the URB completition, but the problem persists even if only the input data is read from the device (no processing at all).
Is this a known issue with Windows 7 / Windows Vista, or are there some special tricks to get Isoc high speed streaming working reliable there?
Regards,
Franz