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diff --git a/ada_user/cpu_usage_statistics.rst b/ada_user/cpu_usage_statistics.rst deleted file mode 100644 index 9bc8784..0000000 --- a/ada_user/cpu_usage_statistics.rst +++ /dev/null @@ -1,152 +0,0 @@ -CPU Usage Statistics -#################### - -Introduction -============ - -The CPU usage statistics manager is an RTEMS support -component that provides a convenient way to manipulate -the CPU usage information associated with each task -The routines provided by the CPU usage statistics manager are: - -- ``rtems.cpu_usage_report`` - Report CPU Usage Statistics - -- ``rtems.cpu_usage_reset`` - Reset CPU Usage Statistics - -Background -========== - -When analyzing and debugging real-time applications, it is important -to be able to know how much CPU time each task in the system consumes. -This support component provides a mechanism to easily obtain this -information with little burden placed on the target. - -The raw data is gathered as part of performing a context switch. RTEMS -keeps track of how many clock ticks have occurred which the task being -switched out has been executing. If the task has been running less than -1 clock tick, then for the purposes of the statistics, it is assumed to -have executed 1 clock tick. This results in some inaccuracy but the -alternative is for the task to have appeared to execute 0 clock ticks. - -RTEMS versions newer than the 4.7 release series, support the ability -to obtain timestamps with nanosecond granularity if the BSP provides -support. It is a desirable enhancement to change the way the usage -data is gathered to take advantage of this recently added capability. -Please consider sponsoring the core RTEMS development team to add -this capability. - -Operations -========== - -Report CPU Usage Statistics ---------------------------- - -The application may dynamically report the CPU usage for every -task in the system by calling the``rtems.cpu_usage_report`` routine. -This routine prints a table with the following information per task: - -- task id - -- task name - -- number of clock ticks executed - -- percentage of time consumed by this task - -The following is an example of the report generated. - - -+------------------------------------------------------------------------------+ -|CPU USAGE BY THREAD | -+-----------+----------------------------------------+-------------------------+ -|ID | NAME | SECONDS | PERCENT | -+-----------+----------------------------------------+---------------+---------+ -|0x04010001 | IDLE | 0 | 0.000 | -+-----------+----------------------------------------+---------------+---------+ -|0x08010002 | TA1 | 1203 | 0.748 | -+-----------+----------------------------------------+---------------+---------+ -|0x08010003 | TA2 | 203 | 0.126 | -+-----------+----------------------------------------+---------------+---------+ -|0x08010004 | TA3 | 202 | 0.126 | -+-----------+----------------------------------------+---------------+---------+ -|TICKS SINCE LAST SYSTEM RESET: 1600 | -|TOTAL UNITS: 1608 | -+------------------------------------------------------------------------------+ - -Notice that the "TOTAL UNITS" is greater than the ticks per reset. -This is an artifact of the way in which RTEMS keeps track of CPU -usage. When a task is context switched into the CPU, the number -of clock ticks it has executed is incremented. While the task -is executing, this number is incremented on each clock tick. -Otherwise, if a task begins and completes execution between -successive clock ticks, there would be no way to tell that it -executed at all. - -Another thing to keep in mind when looking at idle time, is that -many systems – especially during debug – have a task providing -some type of debug interface. It is usually fine to think of the -total idle time as being the sum of the IDLE task and a debug -task that will not be included in a production build of an application. - -Reset CPU Usage Statistics --------------------------- - -Invoking the ``rtems.cpu_usage_reset`` routine resets -the CPU usage statistics for all tasks in the system. - -Directives -========== - -This section details the CPU usage statistics manager’s directives. -A subsection is dedicated to each of this manager’s directives -and describes the calling sequence, related constants, usage, -and status codes. - -cpu_usage_report - Report CPU Usage Statistics ----------------------------------------------- - -**CALLING SEQUENCE:** - -.. code:: c - - procedure CPU_Usage_Report; - -**STATUS CODES: NONE** - -**DESCRIPTION:** - -This routine prints out a table detailing the CPU usage statistics for -all tasks in the system. - -**NOTES:** - -The table is printed using the ``printk`` routine. - -cpu_usage_reset - Reset CPU Usage Statistics --------------------------------------------- - -**CALLING SEQUENCE:** - -.. code:: c - - procedure CPU_Usage_Reset; - -**STATUS CODES: NONE** - -**DESCRIPTION:** - -This routine re-initializes the CPU usage statistics for all tasks -in the system to their initial state. The initial state is that -a task has not executed and thus has consumed no CPU time. -default state which is when zero period executions have occurred. - -**NOTES:** - -NONE - -.. COMMENT: COPYRIGHT (c) 1988-2008. - -.. COMMENT: On-Line Applications Research Corporation (OAR). - -.. COMMENT: All rights reserved. - |