sched, documentation: remove old O(1) scheduler document
Since we don't have O(1) scheduler implementation anymore, remove the legacy doc. Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Wang Chen
Ingo Molnar
parent
5512b3ece0
commit
72fd455ba5
|
|
@ -2,8 +2,6 @@
|
|||
- this file.
|
||||
sched-arch.txt
|
||||
- CPU Scheduler implementation hints for architecture specific code.
|
||||
sched-coding.txt
|
||||
- reference for various scheduler-related methods in the O(1) scheduler.
|
||||
sched-design-CFS.txt
|
||||
- goals, design and implementation of the Complete Fair Scheduler.
|
||||
sched-domains.txt
|
||||
|
|
|
|||
|
|
@ -1,126 +0,0 @@
|
|||
Reference for various scheduler-related methods in the O(1) scheduler
|
||||
Robert Love <rml@tech9.net>, MontaVista Software
|
||||
|
||||
|
||||
Note most of these methods are local to kernel/sched.c - this is by design.
|
||||
The scheduler is meant to be self-contained and abstracted away. This document
|
||||
is primarily for understanding the scheduler, not interfacing to it. Some of
|
||||
the discussed interfaces, however, are general process/scheduling methods.
|
||||
They are typically defined in include/linux/sched.h.
|
||||
|
||||
|
||||
Main Scheduling Methods
|
||||
-----------------------
|
||||
|
||||
void load_balance(runqueue_t *this_rq, int idle)
|
||||
Attempts to pull tasks from one cpu to another to balance cpu usage,
|
||||
if needed. This method is called explicitly if the runqueues are
|
||||
imbalanced or periodically by the timer tick. Prior to calling,
|
||||
the current runqueue must be locked and interrupts disabled.
|
||||
|
||||
void schedule()
|
||||
The main scheduling function. Upon return, the highest priority
|
||||
process will be active.
|
||||
|
||||
|
||||
Locking
|
||||
-------
|
||||
|
||||
Each runqueue has its own lock, rq->lock. When multiple runqueues need
|
||||
to be locked, lock acquires must be ordered by ascending &runqueue value.
|
||||
|
||||
A specific runqueue is locked via
|
||||
|
||||
task_rq_lock(task_t pid, unsigned long *flags)
|
||||
|
||||
which disables preemption, disables interrupts, and locks the runqueue pid is
|
||||
running on. Likewise,
|
||||
|
||||
task_rq_unlock(task_t pid, unsigned long *flags)
|
||||
|
||||
unlocks the runqueue pid is running on, restores interrupts to their previous
|
||||
state, and reenables preemption.
|
||||
|
||||
The routines
|
||||
|
||||
double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
|
||||
|
||||
and
|
||||
|
||||
double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
|
||||
|
||||
safely lock and unlock, respectively, the two specified runqueues. They do
|
||||
not, however, disable and restore interrupts. Users are required to do so
|
||||
manually before and after calls.
|
||||
|
||||
|
||||
Values
|
||||
------
|
||||
|
||||
MAX_PRIO
|
||||
The maximum priority of the system, stored in the task as task->prio.
|
||||
Lower priorities are higher. Normal (non-RT) priorities range from
|
||||
MAX_RT_PRIO to (MAX_PRIO - 1).
|
||||
MAX_RT_PRIO
|
||||
The maximum real-time priority of the system. Valid RT priorities
|
||||
range from 0 to (MAX_RT_PRIO - 1).
|
||||
MAX_USER_RT_PRIO
|
||||
The maximum real-time priority that is exported to user-space. Should
|
||||
always be equal to or less than MAX_RT_PRIO. Setting it less allows
|
||||
kernel threads to have higher priorities than any user-space task.
|
||||
MIN_TIMESLICE
|
||||
MAX_TIMESLICE
|
||||
Respectively, the minimum and maximum timeslices (quanta) of a process.
|
||||
|
||||
Data
|
||||
----
|
||||
|
||||
struct runqueue
|
||||
The main per-CPU runqueue data structure.
|
||||
struct task_struct
|
||||
The main per-process data structure.
|
||||
|
||||
|
||||
General Methods
|
||||
---------------
|
||||
|
||||
cpu_rq(cpu)
|
||||
Returns the runqueue of the specified cpu.
|
||||
this_rq()
|
||||
Returns the runqueue of the current cpu.
|
||||
task_rq(pid)
|
||||
Returns the runqueue which holds the specified pid.
|
||||
cpu_curr(cpu)
|
||||
Returns the task currently running on the given cpu.
|
||||
rt_task(pid)
|
||||
Returns true if pid is real-time, false if not.
|
||||
|
||||
|
||||
Process Control Methods
|
||||
-----------------------
|
||||
|
||||
void set_user_nice(task_t *p, long nice)
|
||||
Sets the "nice" value of task p to the given value.
|
||||
int setscheduler(pid_t pid, int policy, struct sched_param *param)
|
||||
Sets the scheduling policy and parameters for the given pid.
|
||||
int set_cpus_allowed(task_t *p, unsigned long new_mask)
|
||||
Sets a given task's CPU affinity and migrates it to a proper cpu.
|
||||
Callers must have a valid reference to the task and assure the
|
||||
task not exit prematurely. No locks can be held during the call.
|
||||
set_task_state(tsk, state_value)
|
||||
Sets the given task's state to the given value.
|
||||
set_current_state(state_value)
|
||||
Sets the current task's state to the given value.
|
||||
void set_tsk_need_resched(struct task_struct *tsk)
|
||||
Sets need_resched in the given task.
|
||||
void clear_tsk_need_resched(struct task_struct *tsk)
|
||||
Clears need_resched in the given task.
|
||||
void set_need_resched()
|
||||
Sets need_resched in the current task.
|
||||
void clear_need_resched()
|
||||
Clears need_resched in the current task.
|
||||
int need_resched()
|
||||
Returns true if need_resched is set in the current task, false
|
||||
otherwise.
|
||||
yield()
|
||||
Place the current process at the end of the runqueue and call schedule.
|
||||
Loading…
Reference in New Issue