On Thu, Sep 8, 2016 at 2:19 PM, Uwe Kleine-König
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> Hello,
>
> On Thu, Sep 08, 2016 at 09:49:14AM +0800, Hardik A Gohil (WMSC-HW) wrote:
>> I am working on Linux 3.2.0.
>
> Wow, you're still developing on a kernel that is 4.5 years old and
> you're not even taking the stable updates.
since we did development with phyCORE-AM335x-PD13.1.2 which is using 3.2 kernel.
we have already completed production and it wont be a easy task to
shift to 4. series
>
>> We had a requirement to make Linux Real Time so using RT-PREEMPT
>> (patch-3.2-rt10.patch.bz2)
>
> Even if you stick to 3.2.x, there is 3.2.82-rt118.
>
>> We are facing a network hang issue while running the periodic task of 5 ms.
>>
>> cannot ping any more when task is running is ran for some time.
>>
>> I am using Timer fd protocol to achieve this.
>>
>> I would like to know if there is such know issue in this patch.
>>
>> Any help will be appreciated.
>
> I bet you won't find help here until you reproduce the issue with a
> recent kernel (currently there is v4.6.7-rt11) and show the code of your
> periodic task.
I am using iperf to transfer the data over network same problem of
network hang happens
cannot ping any more.
Attached code for rt task
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
--
--
Regards,
Hardik A Gohil
WILLOWGLEN MSC BERHAD (462648-V)
NO 17 JALAN 2/149B, TAMAN SRI ENDAH,
BANDAR BARU SRI PETALING,
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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sched.h>
#include <sys/mman.h>
#include <string.h>
#include <signal.h>
#define MY_PRIORITY (99)
struct periodic_info
{
int timer_fd;
unsigned long long wakeups_missed;
};
static int make_periodic (unsigned int period, struct periodic_info *info)
{
int ret;
unsigned int ns;
unsigned int sec;
int fd;
struct itimerspec itval;
/* Create the timer */
fd = timerfd_create (CLOCK_MONOTONIC, 0);
info->wakeups_missed = 0;
info->timer_fd = fd;
if (fd == -1)
return fd;
/* Make the timer periodic */
sec = period/1000000;
ns = (period - (sec * 1000000)) * 1000;
itval.it_interval.tv_sec = sec;
itval.it_interval.tv_nsec = ns;
itval.it_value.tv_sec = sec;
itval.it_value.tv_nsec = ns;
ret = timerfd_settime (fd, 0, &itval, NULL);
return ret;
}
static void wait_period (struct periodic_info *info)
{
unsigned long long missed;
int ret;
/* Wait for the next timer event. If we have missed any the
number is written to "missed" */
ret = read (info->timer_fd, &missed, sizeof (missed));
if (ret == -1)
{
perror ("read timer");
return;
}
/* "missed" should always be >= 1, but just to be sure, check it is not 0 anyway */
if (missed > 0)
info->wakeups_missed += (missed - 1);
}
int main(void)
{
struct periodic_info info;
struct sched_param param;
struct timeval stop, start;
param.sched_priority = MY_PRIORITY;
if(sched_setscheduler(0, SCHED_FIFO, ¶m) == -1) {
perror("sched_setscheduler failed");
exit(-1);
}
make_periodic(5000, &info); //1 sec
while (1)
{
/* Do useful work */
printf("This is real time task");
gettimeofday(&start, NULL);
wait_period (&info);
gettimeofday(&stop, NULL);
printf("took %lu\n", stop.tv_usec - start.tv_usec);
}
return 0;
}
