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New wireless drivers

While the Linux developers already integrated a new basic framework for WLAN drivers in kernel version 2.6.22 by including the MAC80211 WLAN stack, version 2.6.24 finally offers drivers to go with the new WLAN stack. Hackers went to market and integrated seven new WLAN drivers; these include the iwlwifi project's iwl3945 and iwl4965 drivers which are suitable for the two Intel WLAN modules used in modern Centrino notebooks. Unlike the external ipw3945 driver maintained by Intel, the two new drivers don't need a proprietary demon; the only piece of non-open code required for operation is the firmware the WLAN module executes itself.

Additional new WLAN drivers include rt2x00 for various Ralink WLAN chips, adm8211 for ADMtek ADM8211 chips and b43 for 802.11g chips by Broadcom. Also added were p54 for Intersil 802.11g Prism chips and b43legacy for older Broadcom WLAN hardware (although the kernel already contained the prism54 and bcm43xx drivers to support the same hardware, these drivers didn't use the new WLAN stack, which was thoroughly improved by the developers during the driver update process). The respective CFG80211 configuration interface was extended at the same time to include a Netlink interface.

With these drivers, future Linux kernels should automatically support the majority of current WLAN hardware components - as intended by the developers last May when they decided to switch to the new WLAN stack after programmers had long struggled to agree on a uniform basic framework for WLAN drivers. To round off WLAN support, however, the kernel is still missing the designated ath5k madwifi successor. However, some distributors already supply ath5k - in the same way as Fedora 7 and 8, Ubuntu 7.04 and 7.10 as well as OpenSuse 10.3 already started supporting the WLAN drivers which have now made it into the official Linux kernel months ago. The distributions also come with the firmware files required by many WLAN drivers and configure the hardware automatically.

Further improvements to CFS

Completely Fair Scheduler (CFS), which was integrated with 2.6.23 and is responsible for allocating CPU time to applications, was upgraded extensively in 2.6.24 and is now said to be even more precise and faster than before. In addition, it is now possible to specify groups and schedule CPU time fairly across them (Fair Group Scheduling).

In the standard configuration, CFS allocates the CPU time per user - if three users each run one or several CPU-intensive programs, CFS makes sure that each user receives a third of the total CPU time and will then in turn share the allocated time across the processes. Task Control Groups (see also basic task cgroup framework, 1, 2, 3), however, can be used to specify arbitrary groups and make sure that admins and their friends have enough computing power available for gaming important tasks.

The chief CFS developer had initially assumed that work on the scheduler would by and large be completed with 2.6.24 - however, in the last few weeks, various developers have optimised CFS even further and submitted numerous patches for the next kernel version. It is, therefore, likely that 2.6.25 will bring further improvements to the process scheduler.

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