Re: [dpdk-dev] Question about rte_manage_timer() and eal_intr_handle_interrupts

["Wiles, Keith" <keith.wiles@intel.com>]

> On Nov 2, 2018, at 6:31 AM, Burakov, Anatoly <anatoly.burakov@intel.com> wrote:
> 
> On 02-Nov-18 4:00 AM, Somnath Kotur wrote:
>> Hello,
>>        I'm trying to launch a thread - lcore_mainloop( from
>> examples/timer/main.c ) that runs rte_manage_timer() every 2s from testpmd
>> to ensure the timers i've registered in my driver are checked for expiry  (
>> i even tried putting this thread in my  driver as well,  no difference in
>> results) and i see that while this thread is running, i somehow seem to
>> stop getting interrupts ..infact i don't even
>> see eal_intr_process_interrupts () being called.
>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
>> index ca4e1a4..a8d71d6 100644
>> --- a/app/test-pmd/testpmd.c
>> +++ b/app/test-pmd/testpmd.c
>> @@ -71,6 +71,8 @@
>>  #include <rte_pci.h>
>>  #include <rte_ether.h>
>>  #include <rte_ethdev.h>
>> +#include <rte_cycles.h>
>> +#include <rte_timer.h>
>>  #include <rte_dev.h>
>>  #include <rte_string_fns.h>
>>  #ifdef RTE_LIBRTE_IXGBE_PMD
>> @@ -2524,6 +2526,30 @@ signal_handler(int signum)
>>         }
>>  }
>> +static int
>> +lcore_mainloop(__attribute__((unused)) void *arg)
>> +{
>> +       uint64_t prev_tsc = 0, cur_tsc, diff_tsc;
>> +       unsigned int lcore_id;
>> +
>> +       lcore_id = rte_lcore_id();
>> +       printf("Starting mainloop on core %u\n", lcore_id);
>> +
>> +       while (f_quit == 0) {
>> +               cur_tsc = rte_rdtsc();
>> +               diff_tsc = cur_tsc - prev_tsc;
>> +               /* Schedule every 2 seconds */
>> +               if (diff_tsc > rte_get_timer_hz() * 2) {
>> +                       rte_timer_manage();
>> +                       prev_tsc = cur_tsc;
>> +               } else
>> +                       sleep(1);
>> +       }
>> +       return 0;
>> +}
>> +
>>  int
>>  main(int argc, char** argv)
>>  {
>> @@ -2627,6 +2653,7 @@ main(int argc, char** argv)
>>         if (strlen(cmdline_filename) != 0)
>>                 cmdline_read_from_file(cmdline_filename);
>> +       rte_eal_remote_launch(lcore_mainloop, NULL, 3);
>>         if (interactive == 1) {
>>                 if (auto_start) {
>>                         printf("Start automatic packet forwarding\n");
>> My testpmd cmdline is like so:
>> testpmd -c 0xff -n 3 -- -i portmask=0x3 --nb-cores=3 --rxq=1 --txq=1
>> Any idea what could be the problem ? Is this something that is expected or
>> am i doing something wrong ?
>> Thanks
>> Som
> 
> I may be completely off mark here, but as far as i understand, the EAL Alarm API uses the interrupt thread. The rte_timer API is a high performance timer API and is meant to be managed manually, by periodically[1] calling rte_timer_manage(). If you want something to be called every two seconds, just set up an rte_alarm - there's no need to use the timer API (unless you are on FreeBSD, where alarm API is not officially supported).
> 
> [1] as in, more frequently than every two seconds if you want to have any semblance of timer precision!
> 

Unless we changed it I believe the 

> -- 
> Thanks,
> Anatoly

Regards,
Keith