Le 05/08/2020 à 16:53, Nick Connolly a écrit :
[snip]
>>>>> + if (check_numa()) {
>>>>> + ret = get_mempolicy(&cur_socket_id, NULL, 0, addr,
>>>>> + MPOL_F_NODE | MPOL_F_ADDR);
>>>>> + if (ret < 0) {
>>>>> + RTE_LOG(DEBUG, EAL, "%s(): get_mempolicy: %s\n",
>>>>> + __func__, strerror(errno));
>>>>> + goto mapped;
>>>>> + } else if (cur_socket_id != socket_id) {
>>>>> + RTE_LOG(DEBUG, EAL,
>>>>> + "%s(): allocation happened on wrong socket (wanted
>>>>> %d,
>>>>> got %d)\n",
>>>>> + __func__, socket_id, cur_socket_id);
>>>>> + goto mapped;
>>>>> + }
>>>>> + } else {
>>>>> + if (rte_socket_count() > 1)
>>>>> + RTE_LOG(DEBUG, EAL, "%s(): not checking socket for allocation
>>>>> (wanted %d)\n",
>>>>> + __func__, socket_id);
>>>> nit: maybe an higher log level like WARNING?
>>> Open to guidance here - my concern was that this is going to be generated
>>> for
>>> every call to alloc_seg() and I'm not sure what the frequency will be - I'm
>>> cautious about flooding the log with warnings under 'normal running'. Are
>>> the
>>> implications of running on a multi socket system with NUMA support disabled
>>> in
>>> the kernel purely performance related for the DPDK or is there a functional
>>> correctness issue as well?
>> Is it really a 'normal running' to have CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES
>> in
>> dpdk and not CONFIG_NUMA in the kernel?
>
> I'm not an expert of DPDK, but I think it needs to be treated as 'normal
> running', for the following reasons:
>
> 1. The existing code in eal_memalloc_alloc_seg_bulk() is designed to
> work even if check_numa() indicates that NUMA support is not enabled:
>
> #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
> if (check_numa()) {
> oldmask = numa_allocate_nodemask();
> prepare_numa(&oldpolicy, oldmask, socket);
> have_numa = true;
> }
> #endif
The question was not to return an error, but to display a warning. So the code
will work (after your patch), no problem.
> 2. The DPDK application could be built with
> CONFIG_RTE_EAL_NUMA_AWARE_HUGE_PAGES and then the binary run on
> different systems with and without NUMA support.
In a production environment, it seems odd to have a custom kernel and a generic
dpdk app, it's why I propose the log level WARNING (or NOTICE maybe?).
I let other comment about this, I don't have a strong opinion.
Regards,
Nicolas
