« previous 1 2 3 4 next »

ACPI and power saving

Background information about how Linux uses the standby and suspend modes of modern systems is given in Suspend-to-RAM in Linux - State of the Union Address. In this presentation, kernel developer Rafael J. Wysocki and Intel employee Len Brown, who maintains the ACPI code in the Linux kernel, explain in detail the operation of and problems with the various system standby modes; in this context, they give detailed explanations of numerous internal kernel facts and procedures.

In its final sections, the presentation exposes several limitations of the current kernel code and describes several ways to improve the handling of suspend and hibernate modes currently being developed by the two authors. Linus Torvalds recently integrated some of these improvements into the main development branch of Linux, making them likely components of kernel version 2.6.27 which is expected for mid to end of September.

A whole section of the presentation is dedicated to the hardware problems in connection with Suspend to RAM states, particularly discussing graphics hardware in great detail. Under Linux, graphics hardware often creates problems because the BIOS, kernel and graphics drivers need to reinitialise the graphics core every time the system is taken out of standby – however, this doesn't work reliably on many a system or requires tricks which are outlined in the presentation. A solution for these problems has become available for recent Intel chipsets, and the presenters also hope for improved support of Radeon chips in the near future.

Other presentations discuss various power saving aspects. The presentation Energy-aware task and interrupt management in Linux focuses on the requirements of multi-core CPUs. The cooling aspects of small systems (Ultra Mobile PCs, UMPCs) are discussed in Thermal Management in User Space. Applying Green Computing to clusters and the data center deals with the other end of the hardware spectrum.

Virtualisation and clusters

While in the last few years virtualisation was discussed in many OLS presentations, this topic was not represented quite as prominently this year. Virtualisation of Linux servers: a comparative study provides a good overview of the virtualisation technologies currently available for servers. It contains numerous benchmark results comparing the open source Kqemu, KVM, Linux-VServer, OpenVZ, Qemu, Xen and VirtualBOX virtualisation technologies.

Three IBM employees discuss their experiences with measuring and testing techniques in the field of virtualisation in A Survey of Virtualisation Workloads. In their presentation Containers checkpointing and live migration, several OpenVZ developers describe the live migration of OpenVZ containers from one system to another – for example, this technology is interesting for web hosters who can use it to move a customer's web presence temporarily and instantly to a different server within fractions of a second when they need to carry out maintenance to the server which usually hosts the container.

Xen and KVM have been already capable of live migration for some time – this is discussed in the presentation Live Migration with Pass-through Device for Linux VM by several Intel employees. Grids and cloud computing rather than virtualisation are the topics of Cloud Computing: Coming out of the fog.

Regression and performance testing

Two entire presentations revolve around the systematic testing of new kernel versions. In Keeping the Linux Kernel Honest (Testing Kernel.org kernels), two IBM employees give detailed descriptions of the infrastructures, methods and software they use for regular, partially automated searches for bugs or performance drops with new kernel versions. Together with another IBM developer, one of the presenters also looks at this topic from the perspective of the Linux Test Project: Building a Robust Linux kernel piggybacking The Linux Test Project.

In his presentation If I turn this knob. . . what happens?, Red Hat developer Arnaldo Carvalho de Melo gives an overview of the parameters for optimising performance, using examples to illustrate his techniques and tools for checking the effectiveness of tuning measures. The background and fields of use of modern CPUs' support for the Page Attribute Tables (PAT), which was integrated into the kernel with Linux 2.6.26, is discussed by two Intel employees in PATting Linux. Bazillions of Pages - The Future of Memory Management under Linux by kernel developer Christoph Lameter (SGI) is all about the performance aspects of systems that are currently considered large.

Next: Security, miscellaneous, userlands and more

« previous 1 2 3 4 next »