LatencyTOP is a Linux application for identifying operating system latency within the kernel and find out the operations/actions which cause the latency. LatencyTOP is a tool for software developers to visualize system latencies. Based on these observations, the source code of the application or kernel can be modified to reduce latency. It was released by Intel in 2008 under the GPLv2 license. It works for Intel, AMD and ARM processors.
As of 2021, the project appears inactive with the last commit to the source code in October 2009.
Support for LatencyTOP first appeared in the Linux 2.6.25 kernel, which added the CONFIG_LATENCYTOP instrumentation and a /proc/latency_stats interface for the userspace client. Jonathan CorbetâÂÂs contemporaneous coverage of 2.6.25 highlighted LatencyTop support among the headline features of the release.
According to the projectâÂÂs manual page, latencytop identifies where in the system latency is happening by sampling the kernelâÂÂs latency tracker and attributing delays to specific processes, system calls and stack traces. The curses interface presents a realâÂÂtime topâÂÂstyle list of the worstâÂÂoffending code paths; a GTK+ frontâÂÂend is available as an optional package.
Intel engineer Arjan van de Ven released LatencyTOP in earlyâ¯2008; the last upstream version, 0.5, was tagged in September 2009 and introduced the new GUI.
Although upstream development stalled, distributions continue to ship the dormant codebase:
Modern generic kernels may omit CONFIG_LATENCYTOP, causing the utility to exit with âÂÂPlease enable the CONFIG_LATENCYTOP configuration in your kernelâÂÂ. This issue was reported against Ubuntu 4.4 kernels in 2016 and remains a common hurdle when using distribution kernels.