Files
rtems/cpukit/libmisc/cpuuse/cpuusagereport.c
Sebastian Huber 38b59a6d30 score: Implement forced thread migration
The current implementation of task migration in RTEMS has some
implications with respect to the interrupt latency. It is crucial to
preserve the system invariant that a task can execute on at most one
processor in the system at a time. This is accomplished with a boolean
indicator in the task context. The processor architecture specific
low-level task context switch code will mark that a task context is no
longer executing and waits that the heir context stopped execution
before it restores the heir context and resumes execution of the heir
task. So there is one point in time in which a processor is without a
task. This is essential to avoid cyclic dependencies in case multiple
tasks migrate at once. Otherwise some supervising entity is necessary to
prevent life-locks. Such a global supervisor would lead to scalability
problems so this approach is not used. Currently the thread dispatch is
performed with interrupts disabled. So in case the heir task is
currently executing on another processor then this prolongs the time of
disabled interrupts since one processor has to wait for another
processor to make progress.

It is difficult to avoid this issue with the interrupt latency since
interrupts normally store the context of the interrupted task on its
stack. In case a task is marked as not executing we must not use its
task stack to store such an interrupt context. We cannot use the heir
stack before it stopped execution on another processor. So if we enable
interrupts during this transition we have to provide an alternative task
independent stack for this time frame. This issue needs further
investigation.
2014-05-07 14:26:28 +02:00

228 lines
6.7 KiB
C

/**
* @file
*
* @brief CPU Usage Report
* @ingroup libmisc_cpuuse CPU Usage
*/
/*
* COPYRIGHT (c) 1989-2010.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <inttypes.h>
#include <rtems/cpuuse.h>
#include <rtems/score/objectimpl.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/todimpl.h>
#include <rtems/score/watchdogimpl.h>
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
static bool is_executing_on_a_core(
Thread_Control *the_thread,
Timestamp_Control *time_of_context_switch
)
{
#ifndef RTEMS_SMP
if ( _Thread_Executing->Object.id == the_thread->Object.id ) {
*time_of_context_switch = _Thread_Time_of_last_context_switch;
return true;
}
#else
/* FIXME: Locking */
if ( _Thread_Is_executing_on_a_processor( the_thread ) ) {
*time_of_context_switch =
_Thread_Get_CPU( the_thread )->time_of_last_context_switch;
return true;
}
#endif
return false;
}
#endif
/*
* rtems_cpu_usage_report
*/
void rtems_cpu_usage_report_with_plugin(
void *context,
rtems_printk_plugin_t print
)
{
uint32_t i;
uint32_t api_index;
Thread_Control *the_thread;
Objects_Information *information;
char name[13];
uint32_t ival, fval;
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
Timestamp_Control uptime, total, ran, uptime_at_last_reset;
uint32_t seconds, nanoseconds;
#else
uint32_t total_units = 0;
#endif
if ( !print )
return;
/*
* When not using nanosecond CPU usage resolution, we have to count
* the number of "ticks" we gave credit for to give the user a rough
* guideline as to what each number means proportionally.
*/
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
_Timestamp_Set_to_zero( &total );
uptime_at_last_reset = CPU_usage_Uptime_at_last_reset;
#else
for ( api_index = 1 ; api_index <= OBJECTS_APIS_LAST ; api_index++ ) {
#if !defined(RTEMS_POSIX_API) || defined(RTEMS_DEBUG)
if ( !_Objects_Information_table[ api_index ] )
continue;
#endif
information = _Objects_Information_table[ api_index ][ 1 ];
if ( information ) {
for ( i=1 ; i <= information->maximum ; i++ ) {
the_thread = (Thread_Control *)information->local_table[ i ];
if ( the_thread )
total_units += the_thread->cpu_time_used;
}
}
}
#endif
(*print)(
context,
"-------------------------------------------------------------------------------\n"
" CPU USAGE BY THREAD\n"
"------------+----------------------------------------+---------------+---------\n"
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
" ID | NAME | SECONDS | PERCENT\n"
#else
" ID | NAME | TICKS | PERCENT\n"
#endif
"------------+----------------------------------------+---------------+---------\n"
);
for ( api_index = 1 ; api_index <= OBJECTS_APIS_LAST ; api_index++ ) {
#if !defined(RTEMS_POSIX_API) || defined(RTEMS_DEBUG)
if ( !_Objects_Information_table[ api_index ] )
continue;
#endif
information = _Objects_Information_table[ api_index ][ 1 ];
if ( information ) {
for ( i=1 ; i <= information->maximum ; i++ ) {
the_thread = (Thread_Control *)information->local_table[ i ];
if ( !the_thread )
continue;
rtems_object_get_name( the_thread->Object.id, sizeof(name), name );
(*print)(
context,
" 0x%08" PRIx32 " | %-38s |",
the_thread->Object.id,
name
);
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
{
Timestamp_Control last;
/*
* If this is the currently executing thread, account for time
* since the last context switch.
*/
ran = the_thread->cpu_time_used;
if ( is_executing_on_a_core( the_thread, &last ) ) {
Timestamp_Control used;
_TOD_Get_uptime( &uptime );
_Timestamp_Subtract( &last, &uptime, &used );
_Timestamp_Add_to( &ran, &used );
} else {
_TOD_Get_uptime( &uptime );
}
_Timestamp_Subtract( &uptime_at_last_reset, &uptime, &total );
_Timestamp_Divide( &ran, &total, &ival, &fval );
/*
* Print the information
*/
seconds = _Timestamp_Get_seconds( &ran );
nanoseconds = _Timestamp_Get_nanoseconds( &ran ) /
TOD_NANOSECONDS_PER_MICROSECOND;
(*print)( context,
"%7" PRIu32 ".%06" PRIu32 " |%4" PRIu32 ".%03" PRIu32 "\n",
seconds, nanoseconds,
ival, fval
);
}
#else
if (total_units) {
uint64_t ival_64;
ival_64 = the_thread->cpu_time_used;
ival_64 *= 100000;
ival = ival_64 / total_units;
} else {
ival = 0;
}
fval = ival % 1000;
ival /= 1000;
(*print)( context,
"%14" PRIu32 " |%4" PRIu32 ".%03" PRIu32 "\n",
the_thread->cpu_time_used,
ival,
fval
);
#endif
}
}
}
#ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
seconds = _Timestamp_Get_seconds( &total );
nanoseconds = _Timestamp_Get_nanoseconds( &total ) /
TOD_NANOSECONDS_PER_MICROSECOND;
(*print)(
context,
"------------+----------------------------------------+---------------+---------\n"
" TIME SINCE LAST CPU USAGE RESET IN SECONDS: %7" PRIu32 ".%06" PRIu32 "\n"
"-------------------------------------------------------------------------------\n",
seconds, nanoseconds
);
#else
(*print)(
context,
"------------+----------------------------------------+---------------+---------\n"
" TICKS SINCE LAST SYSTEM RESET: %14" PRIu32 "\n"
" TOTAL UNITS: %14" PRIu32 "\n"
"-------------------------------------------------------------------------------\n",
_Watchdog_Ticks_since_boot - CPU_usage_Ticks_at_last_reset,
total_units
);
#endif
}
void rtems_cpu_usage_report( void )
{
rtems_cpu_usage_report_with_plugin( NULL, printk_plugin );
}