nuttx/sched/sched/sched_cpuload_oneshot.c
Xiang Xiao cde88cabcc Run codespell -w with the latest dictonary again
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2020-02-23 22:27:46 +01:00

305 lines
9.2 KiB
C

/****************************************************************************
* sched/sched/sched_cpuload_oneshot.c
*
* Copyright (C) 2016-2017, 2019 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <time.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/lib/xorshift128.h>
#include <nuttx/timers/oneshot.h>
#include "clock/clock.h"
#ifdef CONFIG_CPULOAD_ONESHOT
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#if !defined(CONFIG_SCHED_CPULOAD) || !defined(CONFIG_SCHED_CPULOAD_EXTCLK)
# error CONFIG_SCHED_CPULOAD and CONFIG_SCHED_CPULOAD_EXTCLK must be defined
#endif
/* CONFIG_SCHED_CPULOAD_TICKSPERSEC is the frequency of the external clock
* source.
*/
#ifndef CONFIG_SCHED_CPULOAD_TICKSPERSEC
# error CONFIG_SCHED_CPULOAD_TICKSPERSEC not defined
#endif
/* CONFIG_CPULOAD_ENTROPY determines that amount of random "jitter"
* that will be added to the nominal sample interval. Specified as a number
* bits.
*/
#ifndef CONFIG_CPULOAD_ENTROPY
# warning CONFIG_CPULOAD_ENTROPY not defined
# define CONFIG_CPULOAD_ENTROPY 0
#endif
/* Calculate the nominal sample interval in microseconds:
*
* nominal = (1,000,000 usec/sec) / Frequency cycles/sec) = Period usec/cycle
*/
#define CPULOAD_ONESHOT_NOMINAL (1000000 / CONFIG_SCHED_CPULOAD_TICKSPERSEC)
#if CPULOAD_ONESHOT_NOMINAL < 1 || CPULOAD_ONESHOT_NOMINAL > 0x7fffffff
# error CPULOAD_ONESHOT_NOMINAL is out of range
#endif
/* Convert the entropy from number of bits to a numeric value */
#define CPULOAD_ONESHOT_ENTROPY (1 << CONFIG_CPULOAD_ENTROPY)
#if CPULOAD_ONESHOT_NOMINAL < CPULOAD_ONESHOT_ENTROPY
# error CPULOAD_ONESHOT_NOMINAL too small for CONFIG_CPULOAD_ENTROPY
#endif
#define CPULOAD_ONESHOT_ENTROPY_MASK (CPULOAD_ONESHOT_ENTROPY - 1)
/****************************************************************************
* Private Types
****************************************************************************/
struct sched_oneshot_s
{
FAR struct oneshot_lowerhalf_s *oneshot;
#if CONFIG_CPULOAD_ENTROPY > 0
struct xorshift128_state_s prng;
int32_t maxdelay;
int32_t error;
#endif
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static void nxsched_oneshot_start(void);
static void nxsched_oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
FAR void *arg);
/****************************************************************************
* Private Data
****************************************************************************/
static struct sched_oneshot_s g_sched_oneshot;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: nxsched_oneshot_start
*
* Description:
* [Re-]start the oneshot timer, applying entropy as configured
*
* Input Parameters:
* None
* lower - An instance of the lower half driver
* arg - The opaque argument provided when the interrupt was registered
*
* Returned Value:
* None
*
****************************************************************************/
static void nxsched_oneshot_start(void)
{
struct timespec ts;
#if CONFIG_CPULOAD_ENTROPY > 0
uint32_t entropy;
#endif
int32_t secs;
int32_t usecs;
/* Get the next delay */
#if CONFIG_CPULOAD_ENTROPY > 0
/* The one shot will be set to this interval:
*
* CPULOAD_ONESHOT_NOMINAL - (CPULOAD_ONESHOT_ENTROPY / 2) + error
* + nrand(CPULOAD_ONESHOT_ENTROPY)
*/
usecs = (CPULOAD_ONESHOT_NOMINAL - CPULOAD_ONESHOT_ENTROPY / 2) +
g_sched_oneshot.error;
/* Add the random value in the range 0..(CPULOAD_ONESHOT_ENTRY - 1) */
entropy = xorshift128(&g_sched_oneshot.prng);
usecs += (int32_t)(entropy & CPULOAD_ONESHOT_ENTROPY_MASK);
DEBUGASSERT(usecs > 0); /* Check for overflow to negative or zero */
/* Make sure that the accumulated value does not exceed the maximum delay */
if (usecs > g_sched_oneshot.maxdelay)
{
tmrwarn("WARNING: Truncating\n");
usecs = g_sched_oneshot.maxdelay;
}
/* Save the new error value */
g_sched_oneshot.error = CPULOAD_ONESHOT_NOMINAL +
g_sched_oneshot.error - usecs;
#else
/* No entropy */
usecs = CPULOAD_ONESHOT_NOMINAL;
#endif
/* Then re-start the oneshot timer */
secs = usecs / 1000000;
usecs -= 100000 * secs;
ts.tv_sec = secs;
ts.tv_nsec = 1000 * usecs;
DEBUGVERIFY(ONESHOT_START(g_sched_oneshot.oneshot,
nxsched_oneshot_callback, NULL, &ts));
}
/****************************************************************************
* Name: nxsched_oneshot_callback
*
* Description:
* This is the callback function that will be invoked when the oneshot
* timer expires.
*
* Input Parameters:
* lower - An instance of the lower half driver
* arg - The opaque argument provided when the interrupt was registered
*
* Returned Value:
* None
*
****************************************************************************/
static void nxsched_oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
FAR void *arg)
{
/* Perform CPU load measurements */
#ifdef CONFIG_HAVE_WEAKFUNCTIONS
if (nxsched_process_cpuload != NULL)
#endif
{
nxsched_process_cpuload();
}
/* Then restart the oneshot */
nxsched_oneshot_start();
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sched_oneshot_extclk
*
* Description:
* Configure to use a oneshot timer as described in
* include/nuttx/timers/oneshot.h to provide external clocking to assess
* the CPU load.
*
* Input Parameters:
* lower - An instance of the oneshot timer interface as defined in
* include/nuttx/timers/oneshot.h
*
* Returned Value:
* None
*
****************************************************************************/
void sched_oneshot_extclk(FAR struct oneshot_lowerhalf_s *lower)
{
#if CONFIG_CPULOAD_ENTROPY > 0
struct timespec ts;
#endif
DEBUGASSERT(lower != NULL && lower->ops != NULL);
DEBUGASSERT(lower->ops->start != NULL);
#if CONFIG_CPULOAD_ENTROPY > 0
DEBUGASSERT(lower->ops->max_delay != NULL);
/* Get the maximum delay */
DEBUGVERIFY(ONESHOT_MAX_DELAY(lower, &ts));
if (ts.tv_sec >= 0)
{
g_sched_oneshot.maxdelay = INT32_MAX;
}
else
{
g_sched_oneshot.maxdelay = ts.tv_nsec / 1000;
}
tmrinfo("madelay = %ld usec\n", (long)g_sched_oneshot.maxdelay);
DEBUGASSERT(CPULOAD_ONESHOT_NOMINAL < g_sched_oneshot.maxdelay);
/* Seed the PRNG */
g_sched_oneshot.prng.w = 97;
g_sched_oneshot.prng.x = 101;
g_sched_oneshot.prng.y = g_sched_oneshot.prng.w << 17;
g_sched_oneshot.prng.z = g_sched_oneshot.prng.x << 25;
#endif
/* Then start the oneshot */
g_sched_oneshot.oneshot = lower;
nxsched_oneshot_start();
}
#endif