Linux kernel Source read Note 2-2.6 Version Scheduler SCHED.C features

From: http://www.ibm.com/developerworks/cn/linux/l-scheduler/

The source code for the 2.6 version scheduler is well encapsulated in the/USR/SRC/LINUX/KERNEL/SCHED.C file. We summarize some useful functions that can be found in this file in table 1.

table 1. Features of the Linux 2.6 scheduler

function name	functions Description
schedule	Scheduler main function. Scheduling the highest priority task execution.
load_balance	Check the CPU to see if there is an imbalance and attempt to migrate the task if it is unbalanced.
effective_prio	returns the effective priority of a task (based on a static policy, but can contain any rewards and penalties).
recalc_task_prio	determines the reward or penalty for a task based on the idle time of the task.
source_load	calculates the load of the source CPU (the CPU from which the task was migrated) properly.
target_load	calculates the payload of the target CPU (the CPU the task may migrate to) fairly.
migration_thread	A high-priority system thread that migrates tasks between CPUs.

The structure of the running queue can also be found in the/usr/src/linux/kernel/sched.c file. The 2.6 version of the scheduler can also provide some statistics (if enabled CONFIG_SCHEDSTATS ). These statistics can be seen from/proc/schedstat in the/proc file system, which provides a lot of data for each CPU in the system, including load balancing and process migration statistics.

Linux kernel Source read Note 2-2.6 Version Scheduler SCHED.C features