- FPU context is stored only if conflict between 2 FPU users or while exporting context of a process to userspace while it is the active user of FPU - FPU has its owner (fpu_owner) which points to the process whose state is currently loaded in FPU - the FPU exception is only turned on when scheduling a process which is not the owner of FPU - FPU state is restored for the process that generated the FPU exception. This process runs immediately without letting scheduler to pick a new process to resolve the FPU conflict asap, to minimize the FPU thrashing and FPU exception hadler execution - faster all non-FPU-exception kernel entries as FPU state is not checked nor saved - removed MF_USED_FPU flag, only MF_FPU_INITIALIZED remains to signal that a process has used FPU in the past
		
			
				
	
	
		
			82 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			82 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* The kernel call implemented in this file:
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 *   m_type:	SYS_CLEAR
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 *
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 * The parameters for this kernel call are:
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 *    m1_i1:	PR_ENDPT		(endpoint of process to clean up)
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 */
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#include "kernel/system.h"
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#include <minix/endpoint.h>
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#if USE_CLEAR
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/*===========================================================================*
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 *				do_clear				     *
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 *===========================================================================*/
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PUBLIC int do_clear(struct proc * caller, message * m_ptr)
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{
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/* Handle sys_clear. Only the PM can request other process slots to be cleared
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 * when a process has exited.
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 * The routine to clean up a process table slot cancels outstanding timers, 
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 * possibly removes the process from the message queues, and resets certain 
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 * process table fields to the default values.
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 */
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  struct proc *rc;
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  int exit_p;
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  int i;
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  if(!isokendpt(m_ptr->PR_ENDPT, &exit_p)) { /* get exiting process */
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      return EINVAL;
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  }
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  rc = proc_addr(exit_p);	/* clean up */
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  release_address_space(rc);
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  /* Don't clear if already cleared. */
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  if(isemptyp(rc)) return OK;
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  /* Check the table with IRQ hooks to see if hooks should be released. */
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  for (i=0; i < NR_IRQ_HOOKS; i++) {
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      if (rc->p_endpoint == irq_hooks[i].proc_nr_e) {
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        rm_irq_handler(&irq_hooks[i]);	/* remove interrupt handler */
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        irq_hooks[i].proc_nr_e = NONE;	/* mark hook as free */
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      } 
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  }
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  /* Remove the process' ability to send and receive messages */
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  clear_endpoint(rc);
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  /* Turn off any alarm timers at the clock. */   
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  reset_timer(&priv(rc)->s_alarm_timer);
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  /* Make sure that the exiting process is no longer scheduled,
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   * and mark slot as FREE. Also mark saved fpu contents as not significant.
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   */
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  RTS_SETFLAGS(rc, RTS_SLOT_FREE);
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  rc->p_misc_flags &= ~MF_FPU_INITIALIZED;
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  /* Release the process table slot. If this is a system process, also
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   * release its privilege structure.  Further cleanup is not needed at
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   * this point. All important fields are reinitialized when the 
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   * slots are assigned to another, new process. 
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   */
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  if (priv(rc)->s_flags & SYS_PROC) priv(rc)->s_proc_nr = NONE;
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#if 0
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  /* Clean up virtual memory */
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  if (rc->p_misc_flags & MF_VM) {
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  	vm_map_default(rc);
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  }
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#endif
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  /* release FPU */
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  if (fpu_owner == rc)
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	  release_fpu();
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  return OK;
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}
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#endif /* USE_CLEAR */
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