From a1b710025b9c686b4ce4ccb6e96889239fe8f122 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beat=20K=C3=BCng?= <beat-kueng@gmx.net>
Date: Sat, 16 Jul 2016 01:55:32 +0200
Subject: [PATCH] Improve new logger update rate (#5073)
* logger: disable some default topics, which are most likely not used
This is also to safe CPU and lower the amount of file descriptors used.
* logger: use the hrt timer for more accurate scheduling
Under NuttX with the default rate of 285Hz, the actual measured rate was
only 200Hz while on Linux it was ~280Hz. The reason is that NuttX only
uses a usleep() granularity of 1ms, so that the typical sleep time is
longer than what we set.
Now the logger waits on a semaphore, which gets activated periodically
with a hrt timer. With this the measured rate is exactly the expected one,
285Hz.
---
src/modules/logger/logger.cpp | 36 +++++++++++++++++++++++++++--------
src/modules/logger/logger.h | 2 +-
2 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/src/modules/logger/logger.cpp b/src/modules/logger/logger.cpp
index 322a99021f..034580d99b 100644
--- a/src/modules/logger/logger.cpp
+++ b/src/modules/logger/logger.cpp
@@ -48,9 +48,11 @@
#include <uORB/topics/vehicle_status.h>
#include <uORB/topics/vehicle_gps_position.h>
+#include <drivers/drv_hrt.h>
#include <px4_includes.h>
#include <px4_getopt.h>
#include <px4_log.h>
+#include <px4_sem.h>
#include <systemlib/mavlink_log.h>
#include <replay/definitions.hpp>
@@ -83,6 +85,12 @@ static Logger *logger_ptr = nullptr;
static int logger_task = -1;
static pthread_t writer_thread;
+/* This is used to schedule work for the logger (periodic scan for updated topics) */
+static void timer_callback(void *arg)
+{
+ px4_sem_t *semaphore = (px4_sem_t *)arg;
+ px4_sem_post(semaphore);
+}
int logger_main(int argc, char *argv[])
@@ -236,7 +244,7 @@ void Logger::print_statistics()
void Logger::run_trampoline(int argc, char *argv[])
{
- unsigned log_interval = 3500;
+ uint32_t log_interval = 3500;
int log_buffer_size = 12 * 1024;
bool log_on_start = false;
bool log_until_shutdown = false;
@@ -327,7 +335,7 @@ void Logger::run_trampoline(int argc, char *argv[])
}
-Logger::Logger(size_t buffer_size, unsigned log_interval, bool log_on_start,
+Logger::Logger(size_t buffer_size, uint32_t log_interval, bool log_on_start,
bool log_until_shutdown, bool log_name_timestamp) :
_arm_override(false),
_log_on_start(log_on_start),
@@ -482,7 +490,6 @@ void Logger::add_default_topics()
add_topic("vehicle_global_velocity_setpoint", 100);
add_topic("battery_status", 300);
add_topic("system_power", 300);
- add_topic("servorail_status", 300);
add_topic("position_setpoint_triplet", 10);
add_topic("att_pos_mocap", 50);
add_topic("vision_position_estimate", 50);
@@ -495,9 +502,6 @@ void Logger::add_default_topics()
add_topic("ekf2_innovations", 20);
add_topic("tecs_status", 20);
add_topic("wind_estimate", 100);
- add_topic("encoders", 50);
- add_topic("time_offset", 1000);
- add_topic("mc_att_ctrl_status", 50);
add_topic("control_state", 20);
add_topic("camera_trigger");
add_topic("cpuload");
@@ -646,7 +650,13 @@ void Logger::run()
start_log();
}
- /* every log_interval usec, check for orb updates */
+ /* init the update timer */
+ struct hrt_call timer_call;
+ px4_sem_t timer_semaphore;
+ px4_sem_init(&timer_semaphore, 0, 0);
+ hrt_call_every(&timer_call, _log_interval, _log_interval, timer_callback, &timer_semaphore);
+
+
while (!_task_should_exit) {
// Start/stop logging when system arm/disarm
@@ -776,9 +786,19 @@ void Logger::run()
}
- usleep(_log_interval);
+ /*
+ * We wait on the semaphore, which periodically gets updated by a high-resolution timer.
+ * The simpler alternative would be:
+ * usleep(max(300, _log_interval - elapsed_time_since_loop_start));
+ * And on linux this is quite accurate as well, but under NuttX it is not accurate,
+ * because usleep() has only a granularity of CONFIG_MSEC_PER_TICK (=1ms).
+ */
+ while (px4_sem_wait(&timer_semaphore) != 0);
}
+ hrt_cancel(&timer_call);
+ px4_sem_destroy(&timer_semaphore);
+
// stop the writer thread
_writer.thread_stop();
diff --git a/src/modules/logger/logger.h b/src/modules/logger/logger.h
index 6270837ec6..eb11ed56bd 100644
--- a/src/modules/logger/logger.h
+++ b/src/modules/logger/logger.h
@@ -75,7 +75,7 @@ struct LoggerSubscription {
class Logger
{
public:
- Logger(size_t buffer_size, unsigned log_interval, bool log_on_start,
+ Logger(size_t buffer_size, uint32_t log_interval, bool log_on_start,
bool log_until_shutdown, bool log_name_timestamp);
~Logger();
--
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