[ANNOUNCE][RFC] PlugSched-6.1.3 for 2.6.13 and 2.6.14-rc4

From: Peter Williams
Date: Thu Oct 13 2005 - 20:01:36 EST

This version contains a new scheduler, spa_svr, which is a minor extension of spa_no_frills intended for use on servers. It makes no attempt to improve interactive responsiveness but includes a simplified version of the throughput bonus mechanism found in Zaphod. This mechanism attempts to minimize the time tasks spend on run queues waiting for CPU access when the system is moderately loaded by giving tasks temporary priority bonuses based on the relationship between the recent average time spent on run queues and on a cpu per cycle. (Although it's effectiveness tends to disappear when the system is fully loaded, it is still useful as considerable delay can be seen on systems with quite low average loads due to lack of serendipity.)

A patch for 2.6.14-rc4 is available at:


and a patch to upgrade the 6.1.2 version for 2.6.13 to 6.1.3 is
available at:


Very Brief Documentation:

You can select a default scheduler at kernel build time. If you wish to
boot with a scheduler other than the default it can be selected at boot
time by adding:


to the boot command line where <scheduler> is one of: ingosched,
nicksched, staircase, spa_no_frills, spa_ws, spa_svr or zaphod. If you don't change the default when you build the kernel the default scheduler will be ingosched (which is the normal scheduler).

The scheduler in force on a running system can be determined by the
contents of:


Control parameters for the scheduler can be read/set via files in:


Peter Williams pwil3058@xxxxxxxxxxxxxx

"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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