On 05/08/2020 16:13, Nicolas Dichtel wrote:
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.
Thanks - appreciate the input - I also have no strong opinions here and
am happy to be guided.
Regards,
Nick
