PCIe bus contention with GTX 680
When using the 295.59 nvidia driver with the GTX 680 graphics card,
we are seeing 100+ microsecond stretches on the PCIe bus when a gnome
X session is running (with no siginificant X display activity).
We use an additional real-time clocks PCIe card in the system and we are
seeing 100+ usec stretches when this real-time clock driver attempts to
read and write it's device registers on the rt clocks card.
If we stop the X session, then the stretches go away.
Other types of nvidia cards to not appear to show this behavior.
I did notice that the nvidia activity that causes these stretches seems to
occur just after (but not during) nv_check_pci_config_space() processing,
presumably somewhere in the binary portion of the nvidia driver.