Is there a way to set the default priority for ktimersoftd/x so that it starts up with lets say a rt prio of -50 instead of doing chrt -p 49 pid of ktimersoftd/0 manually afterwards?
Thanx
Andy
That's set in the kernel, in the following function in kernel/softirq.c:
static inline void ktimer_softirqd_set_sched_params(unsigned int cpu)
{
struct sched_param param = { .sched_priority = 1 };
sched_setscheduler(current, SCHED_FIFO, ¶m);
/* Take over timer pending softirqs when starting */
local_irq_disable();
current->softirqs_raised = local_softirq_pending() & TIMER_SOFTIRQS;
local_irq_enable();
}
So the only way is to patch the kernel and change 1 with something else. I'll be honest, I don't know the consequences of such a change. There's probably a reason why it's 1 and not 50.
NB: This function is only present in the kernel with PREEMPT_RT patch applied.
Related
Is it possible to unreset some GPIO pins while using NVIC_SystemReset function at STM32 ?
Thanks in advance for your answers
Best Regards
I try to reach NVIC_SystemReset function. But not clear inside of this function.
Also this project is running on KEIL
Looks like it is not possible, NVIC_SystemReset issues a general reset of all subsystems.
But probably, instead of system reset, you can just reset all peripheral expect one you need keep working, using peripheral reset registers in Reset and Clock Control module (RCC): RCC_AHB1RSTR, RCC_AHB2RSTR, RCC_APB1RSTR, RCC_APB1RSTR.
Example:
// Issue reset of SPI2, SPI3, I2C1, I2C2, I2C3 on APB1 bus
RCC->APB1RSTR = RCC_APB1RSTR_I2C3RST | RCC_APB1RSTR_I2C2RST | RCC_APB1RSTR_I2C1RST
| RCC_APB1RSTR_SPI3RST | RCC_APB1RSTR_SPI2RST;
__DMB(); // Data memory barrier
RCC->APB1RSTR = 0; // deassert all reset signals
See detailed information in RCC registers description in Reference Manual for your MCU.
You may also need to disable all interrupts in NVIC:
for (int i = 0 ; i < 8 ; i++) NVIC->ICER[i] = 0xFFFFFFFFUL; // disable all interrupts
for (int i = 0 ; i < 8 ; i++) NVIC->ICPR[i] = 0xFFFFFFFFUL; // clear all pending flags
if you want to restart the program, you can reload stack pointer to its top value, located at offset 0 of the flash memory and jump to the start address which is stored at offset 4. Note: flash memory is addressed starting from 0x08000000 address in the address space.
uint32_t stack_top = *((volatile uint32_t*)FLASH_BASE);
uint32_t entry_point = *((volatile uint32_t*)(FLASH_BASE + 4));
__set_MSP(stack_top); // set stack top
__ASM volatile ("BX %0" : : "r" (entry_point | 1) ); // jump to the entry point with bit 1 set
Right now it seems that on every click tick, the running process is preempted and forced to yield the processor, I have thoroughly investigated the code-base and the only relevant part of the code to process preemption is below (in trap.c):
// Force process to give up CPU on clock tick.
// If interrupts were on while locks held, would need to check nlock.
if(myproc() && myproc() -> state == RUNNING && tf -> trapno == T_IRQ0 + IRQ_TIMER)
yield();
I guess that timing is specified in T_IRQ0 + IRQ_TIMER, but I can't figure out how these two can be modified, these two are specified in trap.h:
#define T_IRQ0 32 // IRQ 0 corresponds to int T_IRQ
#define IRQ_TIMER 0
I wonder how I can change the default RR scheduling time-slice (which is right now 1 clock tick, fir example make it 10 clock-tick)?
If you want a process to be executed more time than the others, you can allow it more timeslices, *without` changing the timeslice duration.
To do so, you can add some extra_slice and current_slice in struct proc and modify the TIMER trap handler this way:
if(myproc() && myproc()->state == RUNNING &&
tf->trapno == T_IRQ0+IRQ_TIMER)
{
int current = myproc()->current_slice;
if ( current )
myproc()->current_slice = current - 1;
else
yield();
}
Then you just have to create a syscall to set extra_slice and modify the scheduler function to reset current_slice to extra_slice at process wakeup:
// Switch to chosen process. It is the process's job
// to release ptable.lock and then reacquire it
// before jumping back to us.
c->proc = p;
switchuvm(p);
p->state = RUNNING;
p->current_slice = p->extra_slice
You can read lapic.c file:
lapicinit(void)
{
....
// The timer repeatedly counts down at bus frequency
// from lapic[TICR] and then issues an interrupt.
// If xv6 cared more about precise timekeeping,
// TICR would be calibrated using an external time source.
lapicw(TDCR, X1);
lapicw(TIMER, PERIODIC | (T_IRQ0 + IRQ_TIMER));
lapicw(TICR, 10000000);
So, if you want the timer interrupt to be more spaced, change the TICR value:
lapicw(TICR, 10000000); //10 000 000
can become
lapicw(TICR, 100000000); //100 000 000
Warning, TICR references a 32bits unsigned counter, do not go over 4 294 967 295 (0xFFFFFFFF)
Right now it seems that on every click tick, the running process is preempted and forced to yield the processor, I have thoroughly investigated the code-base and the only relevant part of the code to process preemption is below (in trap.c):
// Force process to give up CPU on clock tick.
// If interrupts were on while locks held, would need to check nlock.
if(myproc() && myproc() -> state == RUNNING && tf -> trapno == T_IRQ0 + IRQ_TIMER)
yield();
I guess that timing is specified in T_IRQ0 + IRQ_TIMER, but I can't figure out how these two can be modified, these two are specified in trap.h:
#define T_IRQ0 32 // IRQ 0 corresponds to int T_IRQ
#define IRQ_TIMER 0
I wonder how I can change the default RR scheduling time-slice (which is right now 1 clock tick, fir example make it 10 clock-tick)?
If you want a process to be executed more time than the others, you can allow it more timeslices, *without` changing the timeslice duration.
To do so, you can add some extra_slice and current_slice in struct proc and modify the TIMER trap handler this way:
if(myproc() && myproc()->state == RUNNING &&
tf->trapno == T_IRQ0+IRQ_TIMER)
{
int current = myproc()->current_slice;
if ( current )
myproc()->current_slice = current - 1;
else
yield();
}
Then you just have to create a syscall to set extra_slice and modify the scheduler function to reset current_slice to extra_slice at process wakeup:
// Switch to chosen process. It is the process's job
// to release ptable.lock and then reacquire it
// before jumping back to us.
c->proc = p;
switchuvm(p);
p->state = RUNNING;
p->current_slice = p->extra_slice
You can read lapic.c file:
lapicinit(void)
{
....
// The timer repeatedly counts down at bus frequency
// from lapic[TICR] and then issues an interrupt.
// If xv6 cared more about precise timekeeping,
// TICR would be calibrated using an external time source.
lapicw(TDCR, X1);
lapicw(TIMER, PERIODIC | (T_IRQ0 + IRQ_TIMER));
lapicw(TICR, 10000000);
So, if you want the timer interrupt to be more spaced, change the TICR value:
lapicw(TICR, 10000000); //10 000 000
can become
lapicw(TICR, 100000000); //100 000 000
Warning, TICR references a 32bits unsigned counter, do not go over 4 294 967 295 (0xFFFFFFFF)
New python user here and first post on this great website. I haven't been able to find an answer to my question so hopefully it is unique.
Using simpy I am trying to create a train subway/metro simulation with failures and repairs periodically built into the system. These failures happen to the train but also to signals on sections of track and on plaforms. I have read and applied the official Machine Shop example (which you can see resemblance of in the attached code) and have thus managed to model random failures and repairs to the train by interrupting its 'journey time'.
However I have not figured out how to model failures of signals on the routes which the trains follow. I am currently just specifying a time for a trip from A to B, which does get interrupted but only due to train failure.
Is it possible to define each trip as its own process i.e. a separate process for sections A_to_B and B_to_C, and separate platforms as pA, pB and pC. Each one with a single resource (to allow only one train on it at a time) and to incorporate random failures and repairs for these section and platform processes? I would also need to perhaps have several sections between two platforms, any of which could experience a failure.
Any help would be greatly appreciated.
Here's my code so far:
import random
import simpy
import numpy
RANDOM_SEED = 1234
T_MEAN_A = 240.0 # mean journey time
T_MEAN_EXPO_A = 1/T_MEAN_A # for exponential distribution
T_MEAN_B = 240.0 # mean journey time
T_MEAN_EXPO_B = 1/T_MEAN_B # for exponential distribution
DWELL_TIME = 30.0 # amount of time train sits at platform for passengers
DWELL_TIME_EXPO = 1/DWELL_TIME
MTTF = 3600.0 # mean time to failure (seconds)
TTF_MEAN = 1/MTTF # for exponential distribution
REPAIR_TIME = 240.0
REPAIR_TIME_EXPO = 1/REPAIR_TIME
NUM_TRAINS = 1
SIM_TIME_DAYS = 100
SIM_TIME = 3600 * 18 * SIM_TIME_DAYS
SIM_TIME_HOURS = SIM_TIME/3600
# Defining the times for processes
def A_B(): # returns processing time for journey A to B
return random.expovariate(T_MEAN_EXPO_A) + random.expovariate(DWELL_TIME_EXPO)
def B_C(): # returns processing time for journey B to C
return random.expovariate(T_MEAN_EXPO_B) + random.expovariate(DWELL_TIME_EXPO)
def time_to_failure(): # returns time until next failure
return random.expovariate(TTF_MEAN)
# Defining the train
class Train(object):
def __init__(self, env, name, repair):
self.env = env
self.name = name
self.trips_complete = 0
self.broken = False
# Start "travelling" and "break_train" processes for the train
self.process = env.process(self.running(repair))
env.process(self.break_train())
def running(self, repair):
while True:
# start trip A_B
done_in = A_B()
while done_in:
try:
# going on the trip
start = self.env.now
yield self.env.timeout(done_in)
done_in = 0 # Set to 0 to exit while loop
except simpy.Interrupt:
self.broken = True
done_in -= self.env.now - start # How much time left?
with repair.request(priority = 1) as req:
yield req
yield self.env.timeout(random.expovariate(REPAIR_TIME_EXPO))
self.broken = False
# Trip is finished
self.trips_complete += 1
# start trip B_C
done_in = B_C()
while done_in:
try:
# going on the trip
start = self.env.now
yield self.env.timeout(done_in)
done_in = 0 # Set to 0 to exit while loop
except simpy.Interrupt:
self.broken = True
done_in -= self.env.now - start # How much time left?
with repair.request(priority = 1) as req:
yield req
yield self.env.timeout(random.expovariate(REPAIR_TIME_EXPO))
self.broken = False
# Trip is finished
self.trips_complete += 1
# Defining the failure
def break_train(self):
while True:
yield self.env.timeout(time_to_failure())
if not self.broken:
# Only break the train if it is currently working
self.process.interrupt()
# Setup and start the simulation
print('Train trip simulator')
random.seed(RANDOM_SEED) # Helps with reproduction
# Create an environment and start setup process
env = simpy.Environment()
repair = simpy.PreemptiveResource(env, capacity = 1)
trains = [Train(env, 'Train %d' % i, repair)
for i in range(NUM_TRAINS)]
# Execute
env.run(until = SIM_TIME)
# Analysis
trips = []
print('Train trips after %s hours of simulation' % SIM_TIME_HOURS)
for train in trains:
print('%s completed %d trips.' % (train.name, train.trips_complete))
trips.append(train.trips_complete)
mean_trips = numpy.mean(trips)
std_trips = numpy.std(trips)
print "mean trips: %d" % mean_trips
print "standard deviation trips: %d" % std_trips
it looks like you are using Python 2, which is a bit unfortunate, because
Python 3.3 and above give you some more flexibility with Python generators. But
your problem should be solveable in Python 2 nonetheless.
you can use sub processes within in a process:
def sub(env):
print('I am a sub process')
yield env.timeout(1)
# return 23 # Only works in py3.3 and above
env.exit(23) # Workaround for older python versions
def main(env):
print('I am the main process')
retval = yield env.process(sub(env))
print('Sub returned', retval)
As you can see, you can use Process instances returned by Environment.process()
like normal events. You can even use return values in your sub proceses.
If you use Python 3.3 or newer, you don’t have to explicitly start a new
sub-process but can use sub() as a sub routine instead and just forward the
events it yields:
def sub(env):
print('I am a sub routine')
yield env.timeout(1)
return 23
def main(env):
print('I am the main process')
retval = yield from sub(env)
print('Sub returned', retval)
You may also be able to model signals as resources that may either be used
by failure process or by a train. If the failure process requests the signal
at first, the train has to wait in front of the signal until the failure
process releases the signal resource. If the train is aleady passing the
signal (and thus has the resource), the signal cannot break. I don’t think
that’s a problem be cause the train can’t stop anyway. If it should be
a problem, just use a PreemptiveResource.
I hope this helps. Please feel welcome to join our mailing list for more
discussions.
I've been struggling with this for a couple of days, and none of the solutions I've found work the way I'd like (I can be completely wrong, I've not used SNMP for a very long time, though).
This is existing code in my company, a perl application that connects to net-snmp agentx using POE::Component::NetSNMP::Agent. MIB defined for this application is defined, with base oid finished in .154. The MIB file defines 3 tables on it: status (.1), statistics (.2) and performance (.3). Everything works fine, registration with the agent goes fine, snmpwalk shows data being updated, etc.
But now a requirement has been implemented, allowing multiple (up to 32) instances of the application running in the same host. And monitoring shall be supported too, which brings the first issue: when connecting to agentX more than once, with the same OID, only one instance connects, and the others are refused.
I've though to make something like this:
.154
.1 (instance 1):
.1 (status table)
.2 (statistics table)
.3 (performance table)
.2 (instance 2):
.1 (status table)
.2 (statistics table)
.3 (performance table)
.3 (instance 3):
.1 (status table)
.2 (statistics table)
.3 (performance table)
[...]
.32 (instance 32):
.1 (status table)
.2 (statistics table)
.3 (performance table)
With this approach, each instance (they know their own id) can register to AgentX with no problems (nice!). Following the model above, tables for status, statistics and performance would be common to all instances.
querying to .154 would show the model above.
querying data for each specific instance by walking to .154.1, .154.2, etc would be possible too.
But I'm unable to get this running properly, as smlint, snmpwalk and iReasoning moan about different data types expected, data is not being shown the right way, etc.
What I've tried so far:
arrays: main index per instance, subindex on status, statistics and performance indexed with { main index, subindex}. Like this: SNMP: ASN.1 MIB Definitions. Referencing a table within a table.
Multiple definitions: re-define every table and component for the 32 instances, with different indices on names. It works moreover, but not exactly the way I was expecting: an snmpwalk of the parent does not show any child, so snmpwalk must be performed using . . . . .154.1, . . . . . .154.2, etc.
I've considered this solution as well: Monitoring multiple java processes on the same host via SNMP. But in my case does not work, as the instances connect to a common agent, they don't have their own agent running in a different port.
I have to admit I'm running out of ideas. Again, I could be completely wrong and could be facing the problem from a wrong perspective.
Is it possible to implement this the way I'm looking for? In SNMPv3 this could possibly be a good use for contexts, but they are not available in net-snmp to my knowledge.
edit
Solution number two, from my list above, is the one working better by far.
From parent MIB, 32 new child OIDs are defined:
sampleServer MODULE-IDENTITY
LAST-UPDATED "201210101200Z"
[...]
DESCRIPTION "Sample Server MIB module"
REVISION "201211191200Z" -- 19 November 2012
DESCRIPTION "Version 0.1"
::= { parentMibs 154 }
instance1 OBJECT IDENTIFIER ::= { sampleServer 1 }
instance2 OBJECT IDENTIFIER ::= { sampleServer 2 }
instance3 OBJECT IDENTIFIER ::= { sampleServer 3 }
instance4 OBJECT IDENTIFIER ::= { sampleServer 4 }
instance5 OBJECT IDENTIFIER ::= { sampleServer 5 }
instance6 OBJECT IDENTIFIER ::= { sampleServer 6 }
[...]
And tables are repeated for each instanceId, a python script wrote the big MIB file for this (I know,
-- the table contains static information for instance number 1
-- this includes version, start time etc
sampleStatusTable1 OBJECT-TYPE
SYNTAX SEQUENCE OF sampleStatusEntry1
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION "sample Server instance1 Status, table"
::= { instance1 1 }
[...]
-- this table contains statistics and sums that change constantly
-- please note that depending on sample_server configuraiton not all
-- of these will be filled in
sampleStatisticsTable1 OBJECT-TYPE
SYNTAX SEQUENCE OF sampleStatisticsEntry1
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION "sample Server Statistics, table"
::= { instance1 2 }
[...]
-- performance figures that reflect the current load of sample_server
samplePerformanceTable1 OBJECT-TYPE
SYNTAX SEQUENCE OF samplePerformanceEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION "sample Server Performance, table"
::= { instance1 3 }
[...]
snmpwalk output for each instance:
snmpwalk -M +/opt/sample_server/docs/mibs -m +COMPANY-SAMPLE-MIB -v2c -cpublic localhost 1.3.6.1.1.1.2.154.1
COMPANY-SAMPLE-MIB::sampleStatusInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatusVersion1 = STRING: "3.58"
COMPANY-SAMPLE-MIB::sampleStatusStartTime1 = STRING: "2014-12-13T00:06:27+0000"
COMPANY-SAMPLE-MIB::sampleStatisticsInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputTransactions1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputErrors1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputTransactions1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrorsRecoverable1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrors1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsEntry1.7 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::samplePerformanceQueueLoad1 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceThroughput1 = INTEGER: 0
snmpwalk -M +/opt/sample_server/docs/mibs -m +COMPANY-SAMPLE-MIB -v2c -cpublic localhost 1.3.6.1.1.1.2.154.2
COMPANY-SAMPLE-MIB::sampleStatusInstance2 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatusVersion2 = STRING: "3.58"
COMPANY-SAMPLE-MIB::sampleStatusStartTime2 = STRING: "2014-12-13T00:06:27+0000"
COMPANY-SAMPLE-MIB::sampleStatisticsInstance2 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputTransactions2 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputErrors2 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputTransactions2 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrorsRecoverable2 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrors2 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsEntry2.7 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceInstance2 = INTEGER: 1
COMPANY-SAMPLE-MIB::samplePerformanceQueueLoad2 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceThroughput2 = INTEGER: 0
But the result it's not as good as I was expecting, because a snmpwalk to master .154 shows the status for .154.1, instead of showing for every instance. Not sure if this is the expected behavior.
snmpwalk -M +/opt/sample_server/docs/mibs -m +COMPANY-SAMPLE-MIB -v2c -cpublic localhost 1.3.6.1.1.1.2.154
COMPANY-SAMPLE-MIB::sampleStatusInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatusVersion1 = STRING: "3.58"
COMPANY-SAMPLE-MIB::sampleStatusStartTime1 = STRING: "2014-12-13T00:06:27+0000"
COMPANY-SAMPLE-MIB::sampleStatisticsInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputTransactions1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPInputErrors1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputTransactions1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrorsRecoverable1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsHTTPOutputErrors1 = INTEGER: 0
COMPANY-SAMPLE-MIB::sampleStatisticsEntry1.7 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceInstance1 = INTEGER: 1
COMPANY-SAMPLE-MIB::samplePerformanceQueueLoad1 = INTEGER: 0
COMPANY-SAMPLE-MIB::samplePerformanceThroughput1 = INTEGER: 0