freebsd-skq/sys/sys/runq.h
Jake Burkholder d5a08a6065 Implement a unified run queue and adjust priority levels accordingly.
- All processes go into the same array of queues, with different
  scheduling classes using different portions of the array.  This
  allows user processes to have their priorities propogated up into
  interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
  32.  We used to have 4 separate arrays of 32 queues each, so this
  may not be optimal.  The new run queue code was written with this
  in mind; changing the number of run queues only requires changing
  constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter.  This
  is intended to be used to create per-cpu run queues.  Implement
  wrappers for compatibility with the old interface which pass in
  the global run queue structure.
- Group the priority level, user priority, native priority (before
  propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
  symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
  This was used to detect when a process' priority had lowered and
  it should yield.  We now effectively yield on every interrupt.
- Activate propogate_priority().  It should now have the desired
  effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
  idle loop.  It interfered with propogate_priority() because
  the idle process needed to do a non-blocking acquire of Giant
  and then other processes would try to propogate their priority
  onto it.  The idle process should not do anything except idle.
  vm_page_zero_idle() will return in the form of an idle priority
  kernel thread which is woken up at apprioriate times by the vm
  system.
- Update struct kinfo_proc to the new priority interface.  Deliberately
  change its size by adjusting the spare fields.  It remained the same
  size, but the layout has changed, so userland processes that use it
  would parse the data incorrectly.  The size constraint should really
  be changed to an arbitrary version number.  Also add a debug.sizeof
  sysctl node for struct kinfo_proc.
2001-02-12 00:20:08 +00:00

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2.6 KiB
C

/*
* Copyright (c) 2001 Jake Burkholder <jake@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _RUNQ_H_
#define _RUNQ_H_
/*
* Run queue parameters.
*/
#define RQ_NQS (64) /* Number of run queues. */
#define RQ_PPQ (4) /* Priorities per queue. */
#define RQB_LEN (2) /* Number of priority status words. */
#define RQB_L2BPW (5) /* Log2(sizeof(rqb_word_t) * NBBY)). */
#define RQB_BPW (1<<RQB_L2BPW) /* Bits in an rqb_word_t. */
#define RQB_BIT(pri) (1 << ((pri) & (RQB_BPW - 1)))
#define RQB_WORD(pri) ((pri) >> RQB_L2BPW)
#define RQB_FFS(word) (ffs(word))
/*
* Type of run queue status word.
*/
typedef u_int32_t rqb_word_t;
/*
* Head of run queues.
*/
TAILQ_HEAD(rqhead, proc);
/*
* Bit array which maintains the status of a run queue. When a queue is
* non-empty the bit corresponding to the queue number will be set.
*/
struct rqbits {
rqb_word_t rqb_bits[RQB_LEN];
};
/*
* Run queue structure. Contains an array of run queues on which processes
* are placed, and a structure to maintain the status of each queue.
*/
struct runq {
struct rqbits rq_status;
struct rqhead rq_queues[RQ_NQS];
};
void runq_add(struct runq *, struct proc *);
int runq_check(struct runq *);
struct proc *runq_choose(struct runq *);
void runq_init(struct runq *);
void runq_remove(struct runq *, struct proc *);
#endif