AMD Performance Counting

Jaswinder Singh Rajput posted some patches to implement performance counting for AMD K7 (and later) processors. The patches count CPU cycles, number of instructions, clock ticks, page faults, context switches, and various other items. Ingo Molnár was very pleased with these patches and tested them, offering some bug reports that Jaswinder was quick to respond to.

Clearer KBuild State When Viewing Help

Cheng Renquan has made some improvements to KBuild. The main user-visible change is to present the currently selected value for any given option visible from that option's help message. Randy Dunlap helped him debug some technical problems but, overall, felt the features were important additions to KBuild.

Improving PCI Detection

As part of a broader swath of PCI patches, Alex Chiang has written some code to create /sys/bus/pci/rescan. Writing a non-zero value to that file will force a rescan of the PCI buses on the system and rediscover any previously removed PCI devices. Alex also wrote companion code to create /sys/bus/pci/devices/ … /rescan, which forces a rescan of a device's parent bus and child buses and rediscovers any devices that had previously been removed from that part of the device tree. He also created /sys/bus/pci/devices/ … /remove, which removes the PCI device and any of its children.