[dpdk-dev] Minimun value of RTE_MAX_LCORE

[Juraj Linkeš]

Hi dpdk devs,

Is there a constraint on how low RTE_MAX_LCORE can be? I'm implementing a discovery mechanism that sets RTE_MAX_LCORE according to the number of host cores, but I'm hitting errors when the values are low:
https://travis-ci.com/github/jlinkes/dpdk/jobs/399596828
Message: Found 2
cores
Message: Found 1
numa nodes

../app/test/test_rcu_qsbr.c:296:54: error: iteration 2 invokes undefined behavior [-Werror=aggressive-loop-optimizations]

../app/test/test_rcu_qsbr.c:315:55: error: array subscript is above array bounds [-Werror=array-bounds]

All VM jobs failed in that Travis build. Travis VMs only have 2 cores, so I tried to put a bound on the build. I set it to 4 and all jobs except GCC shared lib jobs passed, which still threw iteration 4 invokes undefined behavior error:
https://travis-ci.com/github/jlinkes/dpdk/jobs/400004089

../examples/performance-thread/l3fwd-thread/main.c:2338:34: error: iteration 4 invokes undefined behavior [-Werror=aggressive-loop-optimizations]

This happens for number of cores < 32 and looks like a limitation unique to l3fwd (with cores between 4 and 32 - I didn't see the error elsewhere).

Should I use the bound or are these legitimate errors? The fact that only GCC (and not clang) shared lib jobs failed is also suspicious.

Thanks,
Juraj