213 lines
7.2 KiB
C
213 lines
7.2 KiB
C
/************************************************************************
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* sched/sched_cpuload.c
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*
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* Copyright (C) 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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************************************************************************/
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/************************************************************************
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* Included Files
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************************************************************************/
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#include <nuttx/config.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/clock.h>
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#include <arch/irq.h>
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#include "os_internal.h"
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#ifdef CONFIG_SCHED_CPULOAD
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/************************************************************************
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* Pre-processor Definitions
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************************************************************************/
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/* Are we using the system timer, or an external clock? Get the rate
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* of the sampling in ticks per second for the selected timer.
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*/
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#ifdef CONFIG_SCHED_CPULOAD_EXTCLK
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# ifndef CONFIG_SCHED_CPULOAD_TICKSPERSEC
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# error CONFIG_SCHED_CPULOAD_TICKSPERSEC is not defined
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# endif
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# define CPULOAD_TICKSPERSEC CONFIG_SCHED_CPULOAD_TICKSPERSEC
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#else
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# define CPULOAD_TICKSPERSEC CLOCKS_PER_SEC
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#endif
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/************************************************************************
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* Private Type Declarations
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************************************************************************/
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/************************************************************************
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* Public Variables
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************************************************************************/
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/************************************************************************
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* Private Variables
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************************************************************************/
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/* This is the total number of clock tick counts. Essentially the
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* 'denominator' for all CPU load calculations.
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*/
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volatile uint32_t g_cpuload_total;
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/************************************************************************
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* Private Functions
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************************************************************************/
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/************************************************************************
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* Public Functions
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************************************************************************/
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/************************************************************************
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* Name: sched_process_cpuload
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*
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* Description:
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* Collect data that can be used for CPU load measurements.
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*
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* Inputs:
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* None
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*
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* Return Value:
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* None
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*
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* Assumptions/Limitations:
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* This function is called from a timer interrupt handler with all
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* interrupts disabled.
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*
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************************************************************************/
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void weak_function sched_process_cpuload(void)
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{
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FAR struct tcb_s *rtcb = (FAR struct tcb_s*)g_readytorun.head;
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int hash_index;
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int i;
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/* Increment the count on the currently executing thread
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*
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* NOTE also that CPU load measurement data is retained in the g_pidhash
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* table vs. in the TCB which would seem to be the more logic place. It
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* is place in the hash table, instead, to facilitate CPU load adjustments
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* on all threads during timer interrupt handling. sched_foreach() could
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* do this too, but this would require a little more overhead.
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*/
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hash_index = PIDHASH(rtcb->pid);
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g_pidhash[hash_index].ticks++;
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/* Increment tick count. If the accumulated tick value exceed a time
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* constant, then shift the accumulators.
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*/
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if (++g_cpuload_total > (CONFIG_SCHED_CPULOAD_TIMECONSTANT * CPULOAD_TICKSPERSEC))
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{
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uint32_t total = 0;
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/* Divide the tick count for every task by two and recalculate the
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* total.
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*/
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for (i = 0; i < CONFIG_MAX_TASKS; i++)
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{
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g_pidhash[i].ticks >>= 1;
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total += g_pidhash[i].ticks;
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}
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/* Save the new total. */
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g_cpuload_total = total;
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}
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}
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/****************************************************************************
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* Function: clock_cpuload
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*
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* Description:
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* Return load measurement data for the select PID.
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*
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* Parameters:
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* pid - The task ID of the thread of interest. pid == 0 is the IDLE thread.
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* cpuload - The location to return the CPU load
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*
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* Return Value:
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* OK (0) on success; a negated errno value on failure. The only reason
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* that this function can fail is if 'pid' no longer refers to a valid
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* thread.
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*
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* Assumptions:
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*
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****************************************************************************/
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int clock_cpuload(int pid, FAR struct cpuload_s *cpuload)
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{
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irqstate_t flags;
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int hash_index = PIDHASH(pid);
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int ret = -ESRCH;
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DEBUGASSERT(cpuload);
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/* Momentarily disable interrupts. We need (1) the task to stay valid
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* while we are doing these operations and (2) the tick counts to be
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* synchronized when read.
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*/
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flags = irqsave();
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/* Make sure that the entry is valid (TCB field is not NULL) and matches
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* the requested PID. The first check is needed if the thread has exited.
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* The second check is needed for the case where the task associated with
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* the requested PID has exited and the slot has been taken by another
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* thread with a different PID.
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*
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* NOTE also that CPU load measurement data is retained in the g_pidhash
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* table vs. in the TCB which would seem to be the more logic place. It
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* is place in the hash table, instead, to facilitate CPU load adjustments
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* on all threads during timer interrupt handling. sched_foreach() could
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* do this too, but this would require a little more overhead.
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*/
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if (g_pidhash[hash_index].tcb && g_pidhash[hash_index].pid == pid)
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{
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cpuload->total = g_cpuload_total;
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cpuload->active = g_pidhash[hash_index].ticks;
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ret = OK;
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}
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irqrestore(flags);
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return ret;
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}
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#endif /* CONFIG_SCHED_CPULOAD */
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