New Linux kernel boosts memory management, security

Version 2.6.25 of the Linux kernel has been released, Linux coordinator Linus Torvalds announced yesterday on the kernel's development mailing list.

"It's been long promised, but there it is now," he wrote. In addition to updating many drivers, the new kernel has additional support for real-time computing and multiprocessor clustered computing. It also improves memory management and comes with some new security enhancements.

The updates to 2.6.24 can be downloaded in one compressed patch of 12M. The complete log of changes is 7.5M, or about 3,674 pages.

Changes include the addition of:
  • a Memory Resource Controller, a framework for virtual containers to share memory and other resources.
  • Real-time group scheduling, or the ability to offer multiple groups a fixed portion of CPU time.
  • Read Copy Update (RCU) pre-emption support, the ability to pre-empt RCU locking for real-time workloads.
  • A new spinlock for x86 processors. Multiple programs running at once juggle CPU time through the use of spinlocks, which lets one program execute while keeping the others in a holding loop. This new spinlock cuts the potential amount of time that a program may be stuck in a wait state. The spinlock can work up to 65,536 processors at once.
  • Improved measurement of memory use, to more accurately gauge how much memory each program uses.
  • Simplified Mandatory Access Control is a Mandatory Access Control (MAC) implementation, like the National Security Agency's Security Enhanced Linux (SELinux), but easier to set up and use than SELinux. Unlike SELinux, it does not offer role-based access control.
  • LatencyTop, a tool for pinpointing where delays occur in the execution of a program.
  • Completion of address space randomization, a security feature that places programs in different spaces in working memory, so they can't be found easily by attackers.
  • Controller area network protocol support, allowing microcontrollers on a circuit to communicate with one another without a centralized computer facilitating communication.
  • Updated EXT4 file system, to better support large files and extended attributes.

The last version of Linux, 2.6.24, was released in January. This release took longer than expected, according to Torvalds, because of the time it took to track down and correct a hard-to-find bug that reappeared in the recent release candidates of the kernel.

About the Author

Joab Jackson is the senior technology editor for Government Computer News.


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