[dpdk-dev] pthread_barrier_deadlock in -rc1

Tan, Jianfeng jianfeng.tan at intel.com
Wed May 2 10:19:07 CEST 2018



On 5/1/2018 2:46 AM, Olivier Matz wrote:
> Hi Maxime,
>
> Le 30 avril 2018 17:45:52 GMT+02:00, Maxime Coquelin <maxime.coquelin at redhat.com> a écrit :
>> Hi Olivier,
>>
>> On 04/24/2018 04:46 PM, Olivier Matz wrote:
>>> Some parts of dpdk use their own management threads. Most of the
>> time,
>>> the affinity of the thread is not properly set: it should not be
>> scheduled
>>> on the dataplane cores, because interrupting them can cause packet
>> losses.
>>> This patchset introduces a new wrapper for thread creation that does
>>> the job automatically, avoiding code duplication.
>>>
>>> v3:
>>> * new patch: use this API in examples when relevant.
>>> * replace pthread_kill by pthread_cancel. Note that pthread_join()
>>>     is still needed.
>>> * rebase: vfio and pdump do not have control pthreads anymore, and
>> eal
>>>     has 2 new pthreads
>>> * remove all calls to snprintf/strlcpy that truncate the thread name:
>>>     all strings lengths are already < 16.
>>>
>>> v2:
>>> * set affinity to master core if no core is off, as suggested by
>>>     Anatoly
>>>
>>> Olivier Matz (5):
>>>     eal: use sizeof to avoid a double use of a define
>>>     eal: new function to create control threads
>>>     eal: set name when creating a control thread
>>>     eal: set affinity for control threads
>>>     examples: use new API to create control threads
>>>
>>>    drivers/net/kni/Makefile                     |  1 +
>>>    drivers/net/kni/rte_eth_kni.c                |  3 +-
>>>    examples/tep_termination/main.c              | 16 +++----
>>>    examples/vhost/main.c                        | 19 +++-----
>>>    lib/librte_eal/bsdapp/eal/eal.c              |  4 +-
>>>    lib/librte_eal/bsdapp/eal/eal_thread.c       |  2 +-
>>>    lib/librte_eal/common/eal_common_proc.c      | 15 ++----
>>>    lib/librte_eal/common/eal_common_thread.c    | 72
>> ++++++++++++++++++++++++++++
>>>    lib/librte_eal/common/include/rte_lcore.h    | 26 ++++++++++
>>>    lib/librte_eal/linuxapp/eal/eal.c            |  4 +-
>>>    lib/librte_eal/linuxapp/eal/eal_interrupts.c | 17 ++-----
>>>    lib/librte_eal/linuxapp/eal/eal_thread.c     |  2 +-
>>>    lib/librte_eal/linuxapp/eal/eal_timer.c      | 12 +----
>>>    lib/librte_eal/rte_eal_version.map           |  1 +
>>>    lib/librte_vhost/socket.c                    | 25 ++--------
>>>    15 files changed, 135 insertions(+), 84 deletions(-)
>>>
>> I face a deadlock issue with your series, that Jianfeng patch does not
>> resolve ("eal: fix threads block on barrier"). Reverting the series and
>> Jianfeng patch makes the issue to disappear.
>>
>> I face the problem in a VM (not seen on the host):
>> # ./install/bin/testpmd -l 0,1,2 --socket-mem 1024 -n 4 --proc-type
>> auto
>> --file-prefix pg -- --portmask=3 --forward-mode=macswap
>> --port-topology=chained --disable-rss -i --rxq=1 --txq=1 --rxd=256
>> --txd=256 --nb-cores=2 --auto-start
>> EAL: Detected 3 lcore(s)
>> EAL: Detected 1 NUMA nodes
>> EAL: Auto-detected process type: PRIMARY
>> EAL: Multi-process socket /var/run/.pg_unix
>>
>>
>> Then it is stuck. Attaching with GDB, I get below backtrace
>> information:
>>
>> (gdb) info threads
>>    Id   Target Id         Frame
>>    3    Thread 0x7f63e1f9f700 (LWP 8808) "rte_mp_handle"
>> 0x00007f63e2591bfd in recvmsg () at
>> ../sysdeps/unix/syscall-template.S:81
>>    2    Thread 0x7f63e179e700 (LWP 8809) "rte_mp_async"
>> pthread_barrier_wait () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S:71
>> * 1    Thread 0x7f63e32cec00 (LWP 8807) "testpmd" pthread_barrier_wait
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S:71
>> (gdb) bt full
>> #0  pthread_barrier_wait () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S:71
>> No locals.
>> #1  0x0000000000520c54 in rte_ctrl_thread_create
>> (thread=thread at entry=0x7ffe5c895020, name=name at entry=0x869d86
>> "rte_mp_async", attr=attr at entry=0x0,
>> start_routine=start_routine at entry=0x521030 <async_reply_handle>,
>> arg=arg at entry=0x0)
>>      at /root/src/dpdk/lib/librte_eal/common/eal_common_thread.c:207
>>          params = 0x17b1e40
>>          lcore_id = <optimized out>
>>          cpuset = {__bits = {1, 0 <repeats 15 times>}}
>>          cpu_found = <optimized out>
>>          ret = 0
>> #2  0x00000000005220b6 in rte_mp_channel_init () at
>> /root/src/dpdk/lib/librte_eal/common/eal_common_proc.c:674
>>         path = "/var/run\000.pg_unix_*", '\000' <repeats 1301 times>...
>>          dir_fd = 4
>>          mp_handle_tid = 140066969745152
>>          async_reply_handle_tid = 140066961352448
>> #3  0x000000000050c227 in rte_eal_init (argc=argc at entry=23,
>> argv=argv at entry=0x7ffe5c896378) at
>> /root/src/dpdk/lib/librte_eal/linuxapp/eal/eal.c:775
>>          i = <optimized out>
>>          fctret = 11
>>          ret = <optimized out>
>>          thread_id = 140066989861888
>>          run_once = {cnt = 1}
>>          logid = 0x17b1e00 "testpmd"
>>          cpuset = "T}\211\\\376\177", '\000' <repeats 117 times>,
>> "\020", '\000' <repeats 116 times>...
>>       thread_name = "X}\211\\\376\177\000\000\226\301\036\342c\177\000"
>>          __func__ = "rte_eal_init"
>> #4  0x0000000000473214 in main (argc=23, argv=0x7ffe5c896378) at
>> /root/src/dpdk/app/test-pmd/testpmd.c:2597
>>          diag = <optimized out>
>>          port_id = <optimized out>
>>          ret = <optimized out>
>>          __func__ = "main"
>> (gdb) thread 2
>> [Switching to thread 2 (Thread 0x7f63e179e700 (LWP 8809))]
>> #0  pthread_barrier_wait () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S:71
>> 71		cmpl	%edx, (%rdi)
>> (gdb) bt full
>> #0  pthread_barrier_wait () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S:71
>> No locals.
>> #1  0x0000000000520777 in rte_thread_init (arg=<optimized out>) at
>> /root/src/dpdk/lib/librte_eal/common/eal_common_thread.c:156
>>          params = <optimized out>
>>          start_routine = 0x521030 <async_reply_handle>
>>          routine_arg = 0x0
>> #2  0x00007f63e258add5 in start_thread (arg=0x7f63e179e700) at
>> pthread_create.c:308
>>          __res = <optimized out>
>>          pd = 0x7f63e179e700
>>          now = <optimized out>
>>          unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140066961352448,
>> 1212869169857371576, 0, 8392704, 0, 140066961352448,
>> -1291626103561052744, -1291619793368703560}, mask_was_saved = 0}}, priv
>>
>> = {pad = {0x0, 0x0, 0x0, 0x0}, data = {
>>                prev = 0x0, cleanup = 0x0, canceltype = 0}}}
>>          not_first_call = <optimized out>
>>          pagesize_m1 = <optimized out>
>>          sp = <optimized out>
>>          freesize = <optimized out>
>> #3  0x00007f63e22b4b3d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
>> No locals.
>> (gdb) thread 3
>> [Switching to thread 3 (Thread 0x7f63e1f9f700 (LWP 8808))]
>> #0  0x00007f63e2591bfd in recvmsg () at
>> ../sysdeps/unix/syscall-template.S:81
>> 81	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
>> (gdb) bt full
>> #0  0x00007f63e2591bfd in recvmsg () at
>> ../sysdeps/unix/syscall-template.S:81
>> No locals.
>> #1  0x000000000052194e in read_msg (s=0x7f63e1f9d3b0, m=0x7f63e1f9d5a0)
>>
>> at /root/src/dpdk/lib/librte_eal/common/eal_common_proc.c:258
>>          msglen = <optimized out>
>>          control =
>> "\000\000\000\000\000\000\000\000\336~\f\343c\177\000\000\005", '\000'
>> <repeats 23 times>, "\360\371\033\342c\177\000"
>>          cmsg = <optimized out>
>>          iov = {iov_base = 0x7f63e1f9d5a0, iov_len = 332}
>>        msgh = {msg_name = 0x7f63e1f9d3b0, msg_namelen = 110, msg_iov =
>> 0x7f63e1f9d370, msg_iovlen = 1, msg_control = 0x7f63e1f9d380,
>> msg_controllen = 48, msg_flags = 0}
>> #2  mp_handle (arg=<optimized out>) at
>> /root/src/dpdk/lib/librte_eal/common/eal_common_proc.c:346
>>          msg = {type = 0, msg = {name = '\000' <repeats 63 times>,
>> len_param = 0, num_fds = 0, param = '\000' <repeats 20 times>, "\002",
>> '\000' <repeats 234 times>, fds = {0, 0, 0, 0, 0, 0, 0, 0}}}
>>          sa = {sun_family = 55104,
>>            sun_path =
>> "\371\341c\177\000\000\352\372\f\343c\177\000\000\000\000\000\000\000\000\000\000\377\377\377\377\377\377\377\377\000\367\371\341c\177\000\000\030\000\000\000\000\000\000\000p\327\371\341c\177\000\000\000\367\371\341c\177\000\000\000\367\371\341c\177",
>>
>> '\000' <repeats 34 times>, "\200\037\000\000\377\377"}
>> #3  0x00007f63e258add5 in start_thread (arg=0x7f63e1f9f700) at
>> pthread_create.c:308
>>          __res = <optimized out>
>>          pd = 0x7f63e1f9f700
>>          now = <optimized out>
>>          unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140066969745152,
>> 1212869169857371576, 0, 8392704, 0, 140066969745152,
>> -1291625004586295880, -1291619793368703560}, mask_was_saved = 0}}, priv
>>
>> = {pad = {0x0, 0x0, 0x0, 0x0}, data = {
>>                prev = 0x0, cleanup = 0x0, canceltype = 0}}}
>>          not_first_call = <optimized out>
>>          pagesize_m1 = <optimized out>
>>          sp = <optimized out>
>>          freesize = <optimized out>
>> #4  0x00007f63e22b4b3d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
>> No locals.
>>
>> I don't have more info for now.
>>
>
> Thanks for the feedback on this issue. I don't see obvious reason for this deadlock yet.
>
> I'll investigate it asap (not tomorrow, but wednesday). In the worst case, we can revert the series if I cannot find the root cause rapidly.

I might think that the suggestion from Stephen of destroying the barrier 
can help this issue. I'll try to reproduce it and test it before sending 
a patch to fix it.

Thanks,
Jianfeng

>
> Olivier
>



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