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minix/kernel/system.h
Tomas Hruby b4cf88a04f Userspace scheduling 
- cotributed by Bjorn Swift

- In this first phase, scheduling is moved from the kernel to the PM
  server. The next steps are to a) moving scheduling to its own server
  and b) include useful information in the "out of quantum" message,
  so that the scheduler can make use of this information.

- The kernel process table now keeps record of who is responsible for
  scheduling each process (p_scheduler). When this pointer is NULL,
  the process will be scheduled by the kernel. If such a process runs
  out of quantum, the kernel will simply renew its quantum an requeue
  it.

- When PM loads, it will take over scheduling of all running
  processes, except system processes, using sys_schedctl().
  Essentially, this only results in taking over init. As children
  inherit a scheduler from their parent, user space programs forked by
  init will inherit PM (for now) as their scheduler.

 - Once a process has been assigned a scheduler, and runs out of
   quantum, its RTS_NO_QUANTUM flag will be set and the process
   dequeued. The kernel will send a message to the scheduler, on the
   process' behalf, informing the scheduler that it has run out of
   quantum. The scheduler can take what ever action it pleases, based
   on its policy, and then reschedule the process using the
   sys_schedule() system call.

- Balance queues does not work as before. While the old in-kernel
  function used to renew the quantum of processes in the highest
  priority run queue, the user-space implementation only acts on
  processes that have been bumped down to a lower priority queue.
  This approach reacts slower to changes than the old one, but saves
  us sending a sys_schedule message for each process every time we
  balance the queues. Currently, when processes are moved up a
  priority queue, their quantum is also renewed, but this can be
  fiddled with.

- do_nice has been removed from kernel. PM answers to get- and
  setpriority calls, updates it's own nice variable as well as the
  max_run_queue. This will be refactored once scheduling is moved to a
  separate server. We will probably have PM update it's local nice
  value and then send a message to whoever is scheduling the process.

- changes to fix an issue in do_fork() where processes could run out
  of quantum but bypassing the code path that handles it correctly.
  The future plan is to remove the policy from do_fork() and implement
  it in userspace too.
2010-03-29 11:07:20 +00:00

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/* Function prototypes for the system library. The prototypes in this file
* are undefined to do_unused if the kernel call is not enabled in config.h.
* The implementation is contained in src/kernel/system/.
*
* The system library allows to access system services by doing a kernel call.
* System calls are transformed into request messages to the SYS task that is
* responsible for handling the call. By convention, sys_call() is transformed
* into a message with type SYS_CALL that is handled in a function do_call().
*
* Changes:
* Mar 01, 2010 SYS_CLEAR and SYS_EXIT split (Cristiano Giuffrida)
* Jul 30, 2005 created SYS_INT86 to support BIOS driver (Philip Homburg)
* Jul 13, 2005 created SYS_PRIVCTL to manage services (Jorrit N. Herder)
* Jul 09, 2005 updated SYS_KILL to signal services (Jorrit N. Herder)
* Jun 21, 2005 created SYS_NICE for nice(2) kernel call (Ben J. Gras)
* Jun 21, 2005 created SYS_MEMSET to speed up exec(2) (Ben J. Gras)
* Jan 20, 2005 updated SYS_COPY for virtual_copy() (Jorrit N. Herder)
* Oct 24, 2004 created SYS_GETKSIG to support PM (Jorrit N. Herder)
* Oct 10, 2004 created handler for unused calls (Jorrit N. Herder)
* Sep 09, 2004 updated SYS_EXIT to let services exit (Jorrit N. Herder)
* Aug 25, 2004 rewrote SYS_SETALARM to clean up code (Jorrit N. Herder)
* Jul 13, 2004 created SYS_SEGCTL to support drivers (Jorrit N. Herder)
* May 24, 2004 created SYS_SDEVIO to support drivers (Jorrit N. Herder)
* May 24, 2004 created SYS_GETINFO to retrieve info (Jorrit N. Herder)
* Apr 18, 2004 created SYS_VDEVIO to support drivers (Jorrit N. Herder)
* Feb 24, 2004 created SYS_IRQCTL to support drivers (Jorrit N. Herder)
* Feb 02, 2004 created SYS_DEVIO to support drivers (Jorrit N. Herder)
*/
#ifndef SYSTEM_H
#define SYSTEM_H
/* Common includes for the system library. */
#include "debug.h"
#include "kernel.h"
#include "proto.h"
#include "proc.h"
/* Default handler for unused kernel calls. */
_PROTOTYPE( int do_unused, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_exec, (struct proc * caller, message *m_ptr) );
#if ! USE_EXEC
#define do_exec do_unused
#endif
_PROTOTYPE( int do_fork, (struct proc * caller, message *m_ptr) );
#if ! USE_FORK
#define do_fork do_unused
#endif
_PROTOTYPE( int do_newmap, (struct proc * caller, message *m_ptr) );
#if ! USE_NEWMAP
#define do_newmap do_unused
#endif
_PROTOTYPE( int do_clear, (struct proc * caller, message *m_ptr) );
#if ! USE_CLEAR
#define do_clear do_unused
#endif
_PROTOTYPE( int do_trace, (struct proc * caller, message *m_ptr) );
#if ! USE_TRACE
#define do_trace do_unused
#endif
_PROTOTYPE( int do_runctl, (struct proc * caller, message *m_ptr) );
#if ! USE_RUNCTL
#define do_runctl do_unused
#endif
_PROTOTYPE( int do_update, (struct proc * caller, message *m_ptr) );
#if ! USE_UPDATE
#define do_update do_unused
#endif
_PROTOTYPE( int do_exit, (struct proc * caller, message *m_ptr) );
#if ! USE_EXIT
#define do_exit do_unused
#endif
_PROTOTYPE( int do_copy, (struct proc * caller, message *m_ptr) );
#define do_vircopy do_copy
#if ! (USE_VIRCOPY || USE_PHYSCOPY)
#define do_copy do_unused
#endif
_PROTOTYPE( int do_umap, (struct proc * caller, message *m_ptr) );
#if ! USE_UMAP
#define do_umap do_unused
#endif
_PROTOTYPE( int do_memset, (struct proc * caller, message *m_ptr) );
#if ! USE_MEMSET
#define do_memset do_unused
#endif
_PROTOTYPE( int do_abort, (struct proc * caller, message *m_ptr) );
#if ! USE_ABORT
#define do_abort do_unused
#endif
_PROTOTYPE( int do_getinfo, (struct proc * caller, message *m_ptr) );
#if ! USE_GETINFO
#define do_getinfo do_unused
#endif
_PROTOTYPE( int do_privctl, (struct proc * caller, message *m_ptr) );
#if ! USE_PRIVCTL
#define do_privctl do_unused
#endif
_PROTOTYPE( int do_segctl, (struct proc * caller, message *m_ptr) );
#if ! USE_SEGCTL
#define do_segctl do_unused
#endif
_PROTOTYPE( int do_irqctl, (struct proc * caller, message *m_ptr) );
#if ! USE_IRQCTL
#define do_irqctl do_unused
#endif
_PROTOTYPE( int do_devio, (struct proc * caller, message *m_ptr) );
#if ! USE_DEVIO
#define do_devio do_unused
#endif
_PROTOTYPE( int do_vdevio, (struct proc * caller, message *m_ptr) );
#if ! USE_VDEVIO
#define do_vdevio do_unused
#endif
_PROTOTYPE( int do_int86, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_sdevio, (struct proc * caller, message *m_ptr) );
#if ! USE_SDEVIO
#define do_sdevio do_unused
#endif
_PROTOTYPE( int do_kill, (struct proc * caller, message *m_ptr) );
#if ! USE_KILL
#define do_kill do_unused
#endif
_PROTOTYPE( int do_getksig, (struct proc * caller, message *m_ptr) );
#if ! USE_GETKSIG
#define do_getksig do_unused
#endif
_PROTOTYPE( int do_endksig, (struct proc * caller, message *m_ptr) );
#if ! USE_ENDKSIG
#define do_endksig do_unused
#endif
_PROTOTYPE( int do_sigsend, (struct proc * caller, message *m_ptr) );
#if ! USE_SIGSEND
#define do_sigsend do_unused
#endif
_PROTOTYPE( int do_sigreturn, (struct proc * caller, message *m_ptr) );
#if ! USE_SIGRETURN
#define do_sigreturn do_unused
#endif
_PROTOTYPE( int do_times, (struct proc * caller, message *m_ptr) );
#if ! USE_TIMES
#define do_times do_unused
#endif
_PROTOTYPE( int do_setalarm, (struct proc * caller, message *m_ptr) );
#if ! USE_SETALARM
#define do_setalarm do_unused
#endif
_PROTOTYPE( int do_stime, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_vtimer, (struct proc * caller, message *m_ptr) );
#if ! USE_VTIMER
#define do_vtimer do_unused
#endif
_PROTOTYPE( int do_safecopy, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_vsafecopy, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_iopenable, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_vmctl, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_setgrant, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_readbios, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_safemap, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_saferevmap, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_safeunmap, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_sprofile, (struct proc * caller, message *m_ptr) );
#if ! SPROFILE
#define do_sprofile do_unused
#endif
_PROTOTYPE( int do_cprofile, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_profbuf, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_getmcontext, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_setmcontext, (struct proc * caller, message *m_ptr) );
#if ! USE_MCONTEXT
#define do_getmcontext do_unused
#define do_setmcontext do_unused
#endif
_PROTOTYPE( int do_schedule, (struct proc * caller, message *m_ptr) );
_PROTOTYPE( int do_schedctl, (struct proc * caller, message *m_ptr) );
#endif /* SYSTEM_H */
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