The Open Source Development Labs is touting recent advances that make Linux more “serviceable.” The organization says its member companies worked with the open source community to improve kernel dump (kdump) and System Tap (stap), two utilities that aim to help administrators debug production Linux systems without taking them offline.

Kernel dump (kdump)

Kdump is the first kernel crash data dump utility to be added to the mainline Linux kernel tree. It is also available as a set of patches to kexec, the user-space Linux bootloader that it is closely related to.

Kexec can boot a running — or crashed — Linux system directly into a new Linux kernel, without cycling all the way back to the BIOS and bootloader stages. It is often used in enterprise environments, to reduce restart times.

Additionally, in a crash scenario, Kexec can preserve the contents of memory. Kdump appears to enhance this capability by stashing these contents for later, offline analysis.

A recent Kdump whitepaper suggests that Kdump captures dump data very reliably, and is easy to configure and flexible with regard to storage devices and other variables.

The OSDL says recent enhancements to kdump give it “much higher reliability” than previous crash dump tools. Additionally, the utility uses a methodology that has been “endorsed by kernel maintainers,” the organization claims.

Linux kernel maintainer Andrew Morton commented, “kdump is the first crash dump tool accepted into the mainline kernel, and we expect it to be really valuable, permitting us to gather detailed information regarding kernel bugs from our worldwide testing team.”

Another kernel crash dump utility, mini kernel dump (mkdump), is based on a small hypervisor kernel, rather than kexec.

System Tap

The System Tap utility (“stap”) aims to help developers deeply examine running Linux kernels. Users write probes in a simple script language, which stap then translates into C and compiles into a loadable kernel module.

According to the stap tutorial, the utility can also be used to load the kernel module, dynamically compile handlers for probe output, and to unhook the module and extract the module.

The OSDL says that recent System Tap improvements make it the best of several available alternative open source packages that aim to help developers debug and analyze the performance of live production systems. System Tap is especially advanced with regard to its low performance overhead and recompilation automation, the organization says.

Additional new System Tap features reportedly include a scripting language described as “rich” and “easy to understand,” and built-in safety features aimed at protecting running production systems.

OSDL says it facilitated improvements to both kdump and stap, with contributions from Fujitsu, Hitachi, HP, IBM, Intel, NEC, Novell, NTT, Red Hat, and VA Linux.

Availability

Enhanced versions of kdump and stap are available now, in “the latest releases of the leading Linux distributions,” the OSDL says. More details can be found at the respective project websites for kdump and System Tap.

 
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