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Diffstat (limited to 'cpukit/score/src/schedulersimplesmpschedule.c')
| -rw-r--r-- | cpukit/score/src/schedulersimplesmpschedule.c | 271 |
1 files changed, 0 insertions, 271 deletions
diff --git a/cpukit/score/src/schedulersimplesmpschedule.c b/cpukit/score/src/schedulersimplesmpschedule.c deleted file mode 100644 index 471f710ede..0000000000 --- a/cpukit/score/src/schedulersimplesmpschedule.c +++ /dev/null @@ -1,271 +0,0 @@ -/** - * @file - * - * Scheduler Simple SMP Handler / Schedule - */ - -/* - * COPYRIGHT (c) 2011- 2012. - * On-Line Applications Research Corporation (OAR). - * - * The license and distribution terms for this file may be - * found in found in the file LICENSE in this distribution or at - * http://www.rtems.com/license/LICENSE. - */ - -#if HAVE_CONFIG_H -#include "config.h" -#endif - -#include <rtems/system.h> -#include <rtems/score/smp.h> -#include <rtems/score/schedulersimplesmp.h> - -#include <stdio.h> - -/* - * The following is very useful on the scheduler simulator when debugging - * this algorithm. You are not likely to be able to print like this when - * running on a real system. - * - * NOTE: This is NOT using RTEMS_DEBUG because this is not consistency - * checking and is VERY VERY noisy. It is just for debugging - * the algorithm. - */ -#if 0 -#define D(format,...) printk( format, __VA_ARGS__) -#else -#define D(format,...) -#endif - -/* Declaration to avoid warnings */ -bool _Scheduler_simple_smp_Assign( - Thread_Control *consider -); - -/** - * @brief Assign Heir Thread to CPU - * - * This method attempts to find a core for the thread under consideration - * (@a consider) to become heir of. The placement takes into account - * priority, preemptibility, and length of time on core. - * - * Combined with the loop in _Scheduler_simple_smp_Schedule, it attempts - * to faithfully implement the behaviour of the Deterministic Priority - * Scheduler while spreading the threads across multiple cores. - * - * @param[in] consider is the thread under consideration. This means - * that the method is looking for the best core to place it - * as heir. - * - * @return This method returns true if it was able to make @a consider - * the heir on a core and false otherwise. When this returns - * false, there is no point in attempting to place an heir of - * of lower priority. - */ -bool _Scheduler_simple_smp_Assign( - Thread_Control *consider -) -{ - bool found; /* have we found a cpu to place it on? */ - uint32_t found_cpu; /* CPU to place this thread */ - bool blocked; /* CPU has blocked thread? */ - Thread_Control *pheir; /* heir on found cpu to potentially replace */ - Thread_Control *h; - Thread_Control *e; - uint32_t cpu; - - /* - * Initialize various variables to indicate we have not found - * a potential core for the thread under consideration. - */ - found = false; - blocked = false; - found_cpu = 0; - pheir = NULL; - - for ( cpu=0 ; cpu < _SMP_Processor_count ; cpu++ ) { - D( "SCHED CPU=%d consider=0x%08x ASSIGN\n", cpu, consider->Object.id ); - - /* - * If the thread under consideration is already executing or - * heir, then we don't have a better option for it. - */ - e = _Per_CPU_Information[cpu].executing; - if ( e == consider ) { - D( "SCHED CPU=%d Executing=0x%08x considering=0x%08x ASSIGNED\n", - cpu, e->Object.id, consider->Object.id ); - return true; - } - - if ( !_States_Is_ready( e->current_state ) ) { - pheir = e; - found_cpu = cpu; - found = true; - blocked = true; - D( "SCHED CPU=%d PHeir=0x%08x considering=0x%08x BLOCKED\n", - cpu, e->Object.id, consider->Object.id ); - continue; - } - - h = _Per_CPU_Information[cpu].heir; - if ( h == consider ) { - D( "SCHED CPU=%d Heir=0x%08x considering=0x%08x ASSIGNED\n", - cpu, h->Object.id, consider->Object.id ); - return true; - } - - if ( blocked ) - continue; - - /* - * If we haven't found a potential CPU to locate the thread - * under consideration on, we need to consider if this is a - * more important threads first (e.g. priority <). - * - * But when a thread changes its priority and ends up at the end of - * the priority group for the new heir, we also need to schedule - * a new heir. This is the "=" part of the check. - */ - if ( !found ) { - if ( consider->current_priority <= h->current_priority ) { - pheir = h; - found_cpu = cpu; - found = true; - D( "SCHED CPU=%d PHeir=0x%08x considering=0x%08x MAYBE #1\n", - cpu, h->Object.id, consider->Object.id ); - } - - continue; - } - - /* - * ASSERTION: (found == true) - * - * Past this point, we have found a potential heir and are considering - * whether the thread is better placed on another core. It is desirable - * to preempt the lowest priority thread using time on core and - * preemptibility as additional factors. - */ - - /* - * If we have found a potential CPU on which to make the - * thread under consideration the heir, then we need to - * check if the current CPU is a more appropriate place - * for this thread to be placed. - * - * Check 1: heir of potential CPU is more important - * then heir of current CPU. We want to - * replace the least important thread possible. - */ - if ( h->current_priority > pheir->current_priority ) { - pheir = h; - found_cpu = cpu; - D( "SCHED CPU=%d PHeir=0x%08x considering=0x%08x MAYBE #2\n", - cpu, h->Object.id, consider->Object.id ); - continue; - } - - /* - * If the current heir is more important than the potential - * heir, then we should not consider it further in scheduling. - */ - if ( h->current_priority < pheir->current_priority ) - continue; - - /* - * ASSERTION: (h->current_priority == pheir->current_priority). - * - * Past this point, this means we are considering the length of time - * the thread has spent on the time on the CPU core and if it is - * preemptible. - */ - - /* - * If heir of potential CPU and of the current CPU are of the SAME - * priority, then which has been running longer? - * - * Which CPU has had its executing thread longer? - */ - if ( _Timestamp_Less_than( - &_Per_CPU_Information[cpu].time_of_last_context_switch, - &_Per_CPU_Information[found_cpu].time_of_last_context_switch - ) ) { - pheir = h; - found_cpu = cpu; - D( "SCHED CPU=%d PHeir=0x%08x considering=0x%08x LONGER\n", - cpu, h->Object.id, consider->Object.id ); - continue; - } - - /* - * If we are looking at a core with a non-preemptible thread - * for potential placement, then favor a core with a preeemtible - * thread of the same priority. This should help avoid priority - * inversions and let threads run earlier. - */ - if ( !pheir->is_preemptible && h->is_preemptible ) { - D( "SCHED CPU=%d PHeir==0x%08x is NOT PREEMPTIBLE\n", - cpu, pheir->Object.id ); - pheir = h; - found_cpu = cpu; - D( "SCHED CPU=%d PHeir=0x%08x considering=0x%08x PREEMPTIBLE\n", - cpu, h->Object.id, consider->Object.id ); - continue; - - } - } - - /* - * If we found a cpu to make this thread heir of, then we - * need to consider whether we need a dispatch on that CPU. - */ - if ( found ) { - e = _Per_CPU_Information[found_cpu].executing; - D( "SCHED CPU=%d executing=0x%08x considering=0x%08x FOUND\n", - found_cpu, e->Object.id, consider->Object.id ); - _Per_CPU_Information[found_cpu].heir = consider; - if ( !_States_Is_ready( e->current_state ) ) { - D( "SCHED CPU=%d executing not ready dispatch needed\n", found_cpu); - _Per_CPU_Information[found_cpu].dispatch_necessary = true; - } else if ( consider->current_priority < e->current_priority ) { - if ( e->is_preemptible || consider->current_priority == 0 ) { - D( "SCHED CPU=%d preempting\n", found_cpu); - _Per_CPU_Information[found_cpu].dispatch_necessary = true; - } - } - } - - /* - * Return true to indicate we changed an heir. This indicates - * scheduling needs to examine more threads. - */ - return found; -} - -/* - * Reschedule threads -- select heirs for all cores - */ -void _Scheduler_simple_smp_Schedule(void) -{ - Chain_Control *c; - Chain_Node *n; - Thread_Control *t; - uint32_t cpu; - - c = (Chain_Control *)_Scheduler.information; - cpu = 0; - - /* - * Iterate over the first N (where N is the number of CPU cores) threads - * on the ready chain. Attempt to assign each as heir on a core. When - * unable to assign a thread as a new heir, then stop. - */ - for (n = _Chain_First(c); !_Chain_Is_tail(c, n); n = _Chain_Next(n)) { - t = (Thread_Control *)n; - if ( !_Scheduler_simple_smp_Assign( t ) ) - break; - if ( ++cpu >= _SMP_Processor_count ) - break; - } -} |