Some of you have heard me present about the need for idle Linux servers drop from queue. When idle servers don't drop from queue they continue to consume memory real memory resources. I have explained at many occasions that some applications in Linux prevent the virtual machine dropping from queue. They never get "true idle"
PowerTop is an Intel Open Source project to show why an idle Linux system on the laptop empties your batteries very quick. This is exactly the same issue that we have with servers that don't drop from queue. The package requires instrumentation that is in the Linux kernel since 2.6.21 (so RHEL5 and SLES11 for example). On http://www.rvdheij.nl/linux/ is a copy of PowerTop compiled to run on SLES11. After installing, you just run "powertop" to see an overview of the wake-up calls that processes make. This is a diagnostics tool only, you don't run this for a long time because it actually consumes resources itself. But when your performance monitor shows you the idle server does not drop from queue, this is how you can tell why. You can't immediately translate the number of timer interrupts to whether it drops from queue, you need a performance monitor for that. But if the server does not drop from queue and you have a process doing 100 times per second when idle, then that gives some clue on where to look. PS With Linux on z/VM you can ignore recommendations about disabling your USB ports ;-) Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
