LKML Summary Podcast

Audio: COMING SOON

For Wednesday, December 23rd, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: AlacrityVM, get_maintainer.pl, and staging.

AlacrityVM. Gregory Haskins replied to Avi Kivity’s latest comments, in which Avi had said “[t]here was no attempt by Gregory to improve virtio-net”, with a rebuttal of this, noting that he had attempted on several occasions to work with the KVM folks but that they had essentially answered with “sorry, we are doing our own thing instead”. The thread continued along previous lines.

get_maintainer.pl. Joe Perches posted a patch to allow reading a patch from the standard input.

Staging. Greg Kroah-Hartman posted a series of staging patches for 2.6.33. These included “two big things”. Firstly, the “dst” driver was removed because there are no users and development will not be continued. Secondly, a framebuffer driver was added that had been posted before the merge window closed but was held up waiting on other patches landing in Linus’ tree.

In today’s announcements: Git version 1.6.6. Junio C Hamano announced the latest git SCM release as used for kernel development. This release includes a behavior change wherein “git fsck” defaults to “git fsck –full”. Junio also mentions a number of forthcoming compatibility issues in terms of behavior in 1.7.0, such as “git push” refusing to touch a non-checked out tree, and “git send-email” not making deep threads by default.

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.

Audio: COMING SOON

For Tuesday, December 22nd, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: AlacrityVM, and xtime.

AlacrityVM. Ingo Molnar repeated his previous comments concerning “forking” kernel subsystems, agreeing with Anthoy Liguori, who had said that there is a need for a clear understanding of the difference (via “bullet points”) between vbus and vhost-net (one provided by KVM, the other Alacrity), which could be used to consider whether to replace or change the existing kernel code. As he has said before, “to the extent there’s room for improvement here it should be done by shaping KVM, not by forking and rebranding it”. Once again, Gregory provided a calm and reasoned response, noting that he felt various confusion continued to exist surrounding his work, and pull requests. The conversation then took a detour into older review comments.

Xtime. John Stultz posted a request that the removal of xtime_cache be reverted, because xtime now has an overflow issue on rounding that was smoothed and covered by the use of a cache. Apparently, the “fix” is to include sub-nanosecond timekeeping accessor functions in order to avoid the need for any rounding up during accumulation, which can’t be done until three remaining architectures are converted over to GENERIC_TIME. John later followed up with some per-architecture RFC patches just for proof of concept, that had not been tested or even compiled, because he was off on vacation until the New Year and wanted to leave time for suggestions.

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.

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.