LKML Summary Podcast

Audio: COMING SOON

For Monday, December 21st, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: AlacrityVM, asynchronous suspend and resume, kernel threads, and sysctls.

AlacrityVM. Gregory Haskins and Ingo Molnar continued to debate the benefits of various AlacrityVM (a modified KVM-based hypervisor) bits Gregory had posted for inclusion. Greg explained that the bits he had posted were not the core modifications to KVM (which are controversial to some) but simply a “pull request…for drivers to support running a Linux kernel as a guest in this environment, so it actually doesn’t affect KVM in any way”. Avi Kivity countered that this was true, but “these drivers are fairly pointless for virtualization without the host side support” provided by AlacrityVM.

Asynchronous suspend and resume. Rafael J. Wysocki posted some test results of his asynchronous suspend and resume patches, as applied to two different test systems. The results show a clear benefit in time taken for async suspend and resume, although not as dramatic as might be expected (10-20% faster overall). There is a noticeable difference between asynchronous suspend and “upfront” suspend, and the same for resume. “upfront” means that some of the async suspend threads run before the main suspend loop kicks off.

Kernel threads. There has been some discussion over the past few days (in a thread entitled “workqueue thing”) concerning the benefits of concurrent workqueues and the impact of creating many kernel threads in general. Arjan van de Ven has pointed out that kernel thread creation is a lightweight process (yes, pun intended), and that the size of a thread is minimal, but then others in the past have argued for reducing the number of kernel threads overall. If you’re interested, take a look at the (mail) thread.

Sysctl. Andi Kleen posted some patches implementing RCU for reading of string sysctls, in order to avoid races during the read.

In today’s announcements: Git version 1.6.6.rc4. Junio C Hamano announced the latest release of the Git SCM as used for kernel development. The latest version (1.6.6.rc4) comes with several new features (thanks to Junio for pointing out that fixes are released in maintenance releases, and so it is wrong to say “comes with many fixes”, without a qualifier).

The latest kernel release was 2.6.33-rc1.

That’s a summary of today’s Linux Kernel Mailing List traffic, for further information visit www.kernel.org. I’m Jon Masters.