rte_exit() does not terminate the program -- is it a bug or a new feature?

[Gabor LENCSE <lencse@hit.bme.hu>]

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Dear DPDK Developers and Users,

I have met the following issue with my RFC 8219 compliant SIIT and 
stateful NAT64/NAT44 tester, siitperf: 
https://github.com/lencsegabor/siitperf

Its main program starts two sending threads and two receiving threads on 
their exclusively used CPU cores using the rte_eal_remote_launch() 
function, e.g., the code is as follows:

           // start left sender
           if ( rte_eal_remote_launch(send, &spars1, cpu_left_sender) )
             std::cout << "Error: could not start Left Sender." << 
std::endl;

When the test frame sending is finished, the senders check the sending 
time, and if the allowed time was significantly exceeded, the sender 
gives an error message and terminates (itself and also the main program) 
using the rte_exit() function.

This is the code:

   elapsed_seconds = (double)(rte_rdtsc()-start_tsc)/hz;
   printf("Info: %s sender's sending took %3.10lf seconds.\n", side, 
elapsed_seconds);
   if ( elapsed_seconds > duration*TOLERANCE )
     rte_exit(EXIT_FAILURE, "%s sending exceeded the %3.10lf seconds 
limit, the test is invalid.\n", side, duration*TOLERANCE);
   printf("%s frames sent: %lu\n", side, sent_frames);

   return 0;

The above code worked as I expected, while I used siitperf under Debian 
9.13 with DPDK 16.11.11-1+deb9u2. It always displayed the execution time 
of test frame sending, and if the allowed time was significantly exceed, 
then it gave an error message, and it was terminated, thus the sender 
did not print out the number of send frames. And also the main program 
was terminated due to the call of this function: it did not write out 
the "Info: Test finished." message.

However, when I updated siitperf to use it with Ubuntu 22.04 with DPDK 
version "21.11.3-0ubuntu0.22.04.1 amd64", then I experienced something 
rather strange:

In the case, when the sending time is significantly exceeded, I get the 
following messages from the program (I copy here the full output, as it 
may be useful):

root@x033:~/siitperf# cat temp.out
EAL: Detected CPU lcores: 56
EAL: Detected NUMA nodes: 4
EAL: Detected shared linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: No free 2048 kB hugepages reported on node 0
EAL: No free 2048 kB hugepages reported on node 1
EAL: No free 2048 kB hugepages reported on node 2
EAL: No free 2048 kB hugepages reported on node 3
EAL: No available 2048 kB hugepages reported
EAL: VFIO support initialized
EAL: Probe PCI driver: net_ice (8086:159b) device: 0000:98:00.0 (socket 2)
ice_load_pkg_type(): Active package is: 1.3.26.0, ICE OS Default Package 
(single VLAN mode)
EAL: Probe PCI driver: net_ice (8086:159b) device: 0000:98:00.1 (socket 2)
ice_load_pkg_type(): Active package is: 1.3.26.0, ICE OS Default Package 
(single VLAN mode)
TELEMETRY: No legacy callbacks, legacy socket not created
ice_set_rx_function(): Using AVX2 Vector Rx (port 0).
ice_set_rx_function(): Using AVX2 Vector Rx (port 1).
Info: Left port and Left Sender CPU core belong to the same NUMA node: 2
Info: Right port and Right Receiver CPU core belong to the same NUMA node: 2
Info: Right port and Right Sender CPU core belong to the same NUMA node: 2
Info: Left port and Left Receiver CPU core belong to the same NUMA node: 2
Info: Testing initiated at 2023-09-15 07:50:17
EAL: Error - exiting with code: 1
   Cause: Forward sending exceeded the 60.0006000000 seconds limit, the 
test is invalid.
EAL: Error - exiting with code: 1
   Cause: Reverse sending exceeded the 60.0006000000 seconds limit, the 
test is invalid.
root@x033:~/siitperf#

The rte_exit() function seems to work, as the error message appears, and 
the number of sent frames is not displayed, however, the "Info: ..." 
message about the sending time (printed out earlier in the code) is 
missing! This is rather strange!

What is worse, the program does not stop, but *the sender threads and 
the main program remain running (forever)*.

Here is the output of the "top" command:

top - 07:54:24 up 1 day, 14:12,  2 users, load average: 3.02, 2.41, 2.10
Tasks: 591 total,   2 running, 589 sleeping,   0 stopped,   0 zombie
%Cpu0  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu1  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu2  :  0.0 us,  0.0 sy,  0.0 ni, 94.1 id,  0.0 wa,  0.0 hi, 5.9 si,  
0.0 st
%Cpu3  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu4  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu5  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu6  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu7  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu8  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu9  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu10 :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu11 :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu12 :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st
%Cpu13 :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi, 0.0 si,  
0.0 st

CPU0 is the main core, the left sender and the right sender use CPU1 and 
CPU9, respectively. (The receivers that used CPU5 and CPU13 already 
terminated due to their timeout.)

*Thus, rte_exit() behaves differently now: it used the terminate the 
main program but now it does not. *(And it also suppresses some 
previously sent output.)*
*

Is it a bug a new feature?

*How could I achieve the old behavior?* (Or at least the termination of 
the main program by sender threads?)

Thank you very much for you guidance!

Best regards,

Gábor Lencse



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