Re: [dpdk-dev] [dpdk-stable] [PATCH] lib/distributor: fix deadlock issue for aarch64

[David Marchand <david.marchand@redhat.com>]

On Tue, Oct 8, 2019 at 7:06 PM Aaron Conole <aconole@redhat.com> wrote:
>
> Ruifeng Wang <ruifeng.wang@arm.com> writes:
>
> > Distributor and worker threads rely on data structs in cache line
> > for synchronization. The shared data structs were not protected.
> > This caused deadlock issue on weaker memory ordering platforms as
> > aarch64.
> > Fix this issue by adding memory barriers to ensure synchronization
> > among cores.
> >
> > Bugzilla ID: 342
> > Fixes: 775003ad2f96 ("distributor: add new burst-capable library")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> > ---
>
> I see a failure in the distributor_autotest (on one of the builds):
>
> 64/82 DPDK:fast-tests / distributor_autotest  FAIL     0.37 s (exit status 255 or signal 127 SIGinvalid)
>
> --- command ---
>
> DPDK_TEST='distributor_autotest' /home/travis/build/ovsrobot/dpdk/build/app/test/dpdk-test -l 0-1 --file-prefix=distributor_autotest
>
> --- stdout ---
>
> EAL: Probing VFIO support...
>
> APP: HPET is not enabled, using TSC as default timer
>
> RTE>>distributor_autotest
>
> === Basic distributor sanity tests ===
>
> Worker 0 handled 32 packets
>
> Sanity test with all zero hashes done.
>
> Worker 0 handled 32 packets
>
> Sanity test with non-zero hashes done
>
> === testing big burst (single) ===
>
> Sanity test of returned packets done
>
> === Sanity test with mbuf alloc/free (single) ===
>
> Sanity test with mbuf alloc/free passed
>
> Too few cores to run worker shutdown test
>
> === Basic distributor sanity tests ===
>
> Worker 0 handled 32 packets
>
> Sanity test with all zero hashes done.
>
> Worker 0 handled 32 packets
>
> Sanity test with non-zero hashes done
>
> === testing big burst (burst) ===
>
> Sanity test of returned packets done
>
> === Sanity test with mbuf alloc/free (burst) ===
>
> Line 326: Packet count is incorrect, 1048568, expected 1048576
>
> Test Failed
>
> RTE>>
>
> --- stderr ---
>
> EAL: Detected 2 lcore(s)
>
> EAL: Detected 1 NUMA nodes
>
> EAL: Multi-process socket /var/run/dpdk/distributor_autotest/mp_socket
>
> EAL: Selected IOVA mode 'PA'
>
> EAL: No available hugepages reported in hugepages-1048576kB
>
> -------
>
> Not sure how to help debug further.  I'll re-start the job to see if
> it 'clears' up - but I guess there may be a delicate synchronization
> somewhere that needs to be accounted.

Idem, and with the same loop I used before, it can be caught quickly.

# time (log=/tmp/$$.log; while true; do echo distributor_autotest
|taskset -c 0-1 ./build-gcc-static/app/test/dpdk-test --log-level *:8
-l 0-1 >$log 2>&1; grep -q 'Test OK' $log || break; done; cat $log; rm
-f $log)

[snip]

RTE>>distributor_autotest
EAL: Trying to obtain current memory policy.
EAL: Setting policy MPOL_PREFERRED for socket 0
EAL: Restoring previous memory policy: 0
EAL: request: mp_malloc_sync
EAL: Heap on socket 0 was expanded by 2MB
EAL: Trying to obtain current memory policy.
EAL: Setting policy MPOL_PREFERRED for socket 0
EAL: Restoring previous memory policy: 0
EAL: alloc_pages_on_heap(): couldn't allocate physically contiguous space
EAL: Trying to obtain current memory policy.
EAL: Setting policy MPOL_PREFERRED for socket 0
EAL: Restoring previous memory policy: 0
EAL: request: mp_malloc_sync
EAL: Heap on socket 0 was expanded by 8MB
=== Basic distributor sanity tests ===
Worker 0 handled 32 packets
Sanity test with all zero hashes done.
Worker 0 handled 32 packets
Sanity test with non-zero hashes done
=== testing big burst (single) ===
Sanity test of returned packets done

=== Sanity test with mbuf alloc/free (single) ===
Sanity test with mbuf alloc/free passed

Too few cores to run worker shutdown test
=== Basic distributor sanity tests ===
Worker 0 handled 32 packets
Sanity test with all zero hashes done.
Worker 0 handled 32 packets
Sanity test with non-zero hashes done
=== testing big burst (burst) ===
Sanity test of returned packets done

=== Sanity test with mbuf alloc/free (burst) ===
Line 326: Packet count is incorrect, 1048568, expected 1048576
Test Failed
RTE>>
real    0m36.668s
user    1m7.293s
sys    0m1.560s

Could be worth running this loop on all tests? (not talking about the
CI, it would be a manual effort to catch lurking issues).


-- 
David Marchand