Logo RTAI & LTT Choi Sung Chul. What is the RTAI ? Realtime Application Interface A patch to the...
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Transcript of Logo RTAI & LTT Choi Sung Chul. What is the RTAI ? Realtime Application Interface A patch to the...
Logo
RTAI & LTTRTAI & LTT
Choi Sung ChulChoi Sung Chul
What is the RTAI ?
Realtime Application Interface A patch to the Linux kernel which introduces a
hardware abstraction layer A broad variety of services which make realtim
e programmers' lifes easier Working with POSIX compliant or native RTAI
realtime tasks Linux application is able to execute without an
y modification
What kind of functions does RTAI support?
real time scheduler module - Task functions - Timing functions - Semaphore functions - Mailbox functions - Intertask communication functions
Fifo services Shared memory Posix pthread and pqueue(msg queue)
How to make a RTAI program It is a similar to make linux kernel module Use several functions for RTAI program Example RTAI program
int init_module(void){ RTIME tick_period; rt_set_periodic_mode(); rt_task_init(&rt_task, fun, 1, STACK_SIZE, TASK_PRIORITY, 1, 0); rtf_create(FIFO, 8000); tick_period = start_rt_timer(nano2count(TICK_PERIOD)); rt_task_make_periodic(&rt_task, rt_get_time() + tick_period, tick_period); return 0;}
void cleanup_module(void){ stop_rt_timer(); rtf_destroy(FIFO); rt_task_delete(&rt_task); return;}
What is the LTT?
Linux Trace Toolkit Linux kernel tracing capabilities with 48 unique
Trace Points Variable-length events minimizing overall trace size Minimal performance overhead (< 2.5 %). Micro-second event time-stamps graphical user interface with event graph, system
and per-process analysis, and raw event descriptions.
Support for the Real-Time Application Interface
Why LTT?
It is too hard to debug kernel like Real Time program
It isn’t able to be checked transmitting and receiving message or signal accuracy
We can see the kernel event and message transferring easily to use LTT
LTT can make user defined event(custom event) it needs not use “printk”!!
LTT can dump selected event and message. So, we can save it and analysis anytime
Install RTAI & LTT (1)
Need files
- TraceToolkit 0.95a http://www.opersys.com/LTT/
- linux kernel 2.4.16
http://www.kernel.org
- RTAI 24.1.11 http://www.aero.polimi.it/RTAI/
Compiler
- gcc version 2.95.3
Install RTAI & LTT (2)
Linux Kenel Patch & CompilePatch from LTT patchs directory
- #~/linux>patch -p1 < ~/TraceToolkit-0.9.5a/Patches/patch-ltt-linux-2.4.16-rthal5f-020415-1.14
Modify kernel source (2 files) - linux/arch/i386/kernel/irq.c ,linux/include/asm-i386/system.h
Kernel setting & compile - NO : Set version information on all module symbols - YES : Real-Time Hardware Abstraction Layer - Module : Kernel event tracing support - YES : RTAI event tracing support - APM : disable
Make boot image & Reboot - Add boot image to lilo or grub
Install RTAI & LTT (3)
Install RTAI - #> Configure –menu Menu Setting
Modify sources (2 files) - arch/i386/rtai.c , upscheduler/rtai_sched.c
Make & make install Load modules
$> modprobe -v rtai /sbin/insmod /lib/modules/2.4.16-rthal5trace/rtai/rtai_tracer.o
Using /lib/modules/2.4.16-rthal5-trace/rtai/rtai_tracer.oSymbol version prefix 'smp_'/sbin/insmod /lib/modules/2.4.16-rthal5-trace/rtai/rtai.oUsing /lib/modules/2.4.16-rthal5-trace/rtai/rtai.o$>lsmodModule Size Used by Tainted: P rtai 56320 0 (unused)rtai_tracer 9024 0 [rtai]binfmt_misc 7524 1 ….
Install RTAI & LTT (3)
Configire –with-rtai & make install Execute createdev.sh (make node /dev/tracer)
- $> ./createdev.sh Deleting old tracer nodes: /dev/tracer and /dev/tracerU
Found tracer device with major number: 253 Creating new tracer nodes: /dev/tracer and /dev/tracerU
Trace time(sec)- this records data(kernel and app trace event) for require time
Traceview- graphic tool for event graph, system and per-process analysis, and raw event descriptions
LTT & Traceview Screenshot
Example1 for using LTT in a RTAI program
Offered ex - /rtai-24.1.11/examples/msgsw This example features NTASKS(8) real-time
tasks running periodically On each period a server task is messaged to
set/reset a bit on the parallel port By choosing an appropriate timing one can
produce a rectangular wave which can be watched on an oscilloscope plugged into it
Block diagram for example1
TaskDriver
TaskFun 1
TaskFun 2
TaskFun 3
TaskFun 4
TaskFun 5
TaskFun 6
TaskFun 7
rt_send
rt_rpc
rt_rpc
rt_rpc
rt_send
rt_send
rt_send
ParallelPort
Control
Flow diagram for example1Flow diagram for example1Driver Task Fun Task
rt_send Msg(0)
Parallel Port
LED OFF(Port 1 is OFF)
Task 1
Ack of rt_send from RTAI
rt_rpc Msg(1) Task 2
LED ON(Port 1 is ON)rt_return Msg(0)
rt_task_wait_period
rt_task_wait_period
rt_send Msg(0)LED OFF(Port 1 is OFF)
Task 3
Ack of rt_send from RTAI
rt_rpc Msg(1) Task 4
LED ON(Port 1 is ON)rt_return Msg(0)
rt_task_wait_period
rt_task_wait_period
rt_send Msg(0)LED OFF(Port 1 is OFF)
Task 5
Ack of rt_send from RTAI
rt_rpc Msg(1) Task 6
LED ON(Port 1 is ON)rt_return Msg(0)
rt_task_wait_period
rt_task_wait_period
rt_send Msg(0)LED OFF(Port 1 is OFF)
Task 7
Ack of rt_send from RTAI
Traceview of example1
Zoom function of Traceview
Example2 for using LTT in a RTAI program Simple wave actived generator simulation Let’s wave factor = sin(t) A sensor for wave height Its pen of Turbine changes direction when heig
ht reaches max or min value Turbine always rotate one side direction.
Simplify model for wave actived generator
Always one side direction
Falling time
Rising time
Turn direction
Turn direction
Simple SDL for example2 program
TaskWave
Time++Height = 1+GetSin(Time)
TaskSensor
Height reaches MAX value?
Height reaches MIN value?
No
rt_send MSG_TURN_RIGHT
rt_send MSG_TURN_LEFT
TaskTurn
rt_receiveMSG_TURN_RIGHT
rt_receiveMSG_TURN_LEFT
DoTurnRight DoTurnLeft
User defined custom event
When it can’t be used printk and must be checked variable
LTT support user define eventint trace_create_event ( char* /* String describing event type */,
char* /* String to format standard event description */,int /* Type of formatting used to log event data */,char* /* Data specific to format */);
int trace_destroy_event( int /* The event ID given by trace_create_event() */);int trace_user_event(
int /* The event ID given by trace_create_event() */,int /* The size of the raw data */,void* /* Pointer to the raw event data */);
Custom event of example1
Make eventtraceId = trace_create_event("WaveActivedGen", "%s", CUSTOM_EVENT_FORMAT_TYPE_STR, NULL); trace_std_formatted_event(traceId, "Trace init_module");
Wave height valuesprintf(dbgMsg, "height:%d", (int)wave_height); trace_std_forma
tted_event(traceId, dbgMsg);
Recv turn event trace_std_formatted_event(traceId, "Do Pen Turn Right!");
trace_std_formatted_event(traceId, "Do Pen Turn Left!");
Dump event and message
Traceview -> menu -> file ->dump file Select dump message or event Example2 custom message dump
Trace start time: (1097134998, 633202) Trace end time: (1097135001, 614397) Trace duration: (2, 981195)
Number of occurences of:Events: 22029 Scheduling changes: 821 Kernel timer tics: 228 System call entries: 3006 System call exits: 3005 Trap entries: 0 Trap exits: 0 IRQ entries: 337 IRQ exits: 337 Bottom halves: 228 Timer expiries: 73 Page allocations: 417 Page frees: 415 Packets Out: 0 Packets In: 112
####################################################################Event Time PID Length Description####################################################################Event creation 1,097,134,998,633,204 N/A 391 NEW EVENT TYPE : WaveActivedGen; CUSTOM EVENT ID : 24RT-Timer 1,097,134,998,633,860 N/A 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,633,866 N/A 30 height:183RT-Task 1,097,134,998,633,866 N/A 28 WAIT PERIODRT-Timer 1,097,134,998,640,546 1138 16 TIMER EXPIRYRT-Task 1,097,134,998,640,551 1138 28 WAIT PERIODWaveActivedGen 1,097,134,998,640,558 1138 30 height:185RT-Task 1,097,134,998,640,558 1138 28 WAIT PERIODRT-Timer 1,097,134,998,647,236 1138 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,647,241 1138 30 height:187RT-Task 1,097,134,998,647,242 1138 28 WAIT PERIODRT-Timer 1,097,134,998,653,921 1253 16 TIMER EXPIRYRT-Task 1,097,134,998,653,925 1253 28 WAIT PERIODWaveActivedGen 1,097,134,998,653,932 1253 30 height:189RT-Task 1,097,134,998,653,933 1253 28 WAIT PERIODRT-Timer 1,097,134,998,660,610 1138 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,660,620 1138 30 height:190RT-Task 1,097,134,998,660,620 1138 28 WAIT PERIODRT-Timer 1,097,134,998,667,295 0 16 TIMER EXPIRYRT-Task 1,097,134,998,667,297 0 28 WAIT PERIODWaveActivedGen 1,097,134,998,667,300 0 30 height:192RT-Task 1,097,134,998,667,300 0 28 WAIT PERIODRT-Timer 1,097,134,998,673,985 0 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,673,987 0 30 height:193RT-Task 1,097,134,998,673,987 0 28 WAIT PERIODRT-Timer 1,097,134,998,680,670 0 16 TIMER EXPIRYRT-Task 1,097,134,998,680,672 0 28 WAIT PERIODWaveActivedGen 1,097,134,998,680,676 0 30 height:194RT-Task 1,097,134,998,680,676 0 28 WAIT PERIODRT-Timer 1,097,134,998,687,359 0 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,687,361 0 30 height:195RT-Task 1,097,134,998,687,361 0 28 WAIT PERIODRT-Timer 1,097,134,998,694,046 0 16 TIMER EXPIRYRT-Task 1,097,134,998,694,047 0 28 WAIT PERIODWaveActivedGen 1,097,134,998,694,050 0 30 height:196RT-Task 1,097,134,998,694,051 0 28 WAIT PERIODRT-Timer 1,097,134,998,700,736 0 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,700,739 0 30 height:197
WaveActivedGen 1,097,134,998,754,238 0 30 height:199RT-Task 1,097,134,998,754,239 0 28 WAIT PERIODRT-Timer 1,097,134,998,760,923 0 16 TIMER EXPIRYRT-Message 1,097,134,998,760,924 0 24 SEND => TASK : 1; MSG : 1dWaveActivedGen 1,097,134,998,760,927 0 38 Do Pen Turn Right!RT-Message 1,097,134,998,760,927 0 24 RECEIVE => TASK : 2RT-Task 1,097,134,998,760,928 0 28 WAIT PERIODWaveActivedGen 1,097,134,998,760,931 0 30 height:199RT-Task 1,097,134,998,760,932 0 28 WAIT PERIODRT-Timer 1,097,134,998,767,612 0 16 TIMER EXPIRYWaveActivedGen 1,097,134,998,767,614 0 30 height:199RT-Task 1,097,134,998,767,614 0 28 WAIT PERIODRT-Timer 1,097,134,998,774,299 0 16 TIMER EXPIRYRT-Task 1,097,134,998,774,300 0 28 WAIT PERIODWaveActivedGen 1,097,134,998,774,303 0 30 height:198