sfc: default config to 1 channel/core in local NUMA node only

Handling channels from CPUs in different NUMA node can penalize
performance, so better configure only one channel per core in the same
NUMA node than the NIC, and not per each core in the system.

Fallback to all other online cores if there are not online CPUs in local
NUMA node.
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/sfc/efx_channels.c

@@ -78,31 +78,48 @@ static const struct efx_channel_type efx_default_channel_type = {
  * INTERRUPTS
  *************/
 
-static unsigned int efx_wanted_parallelism(struct efx_nic *efx)
+static unsigned int count_online_cores(struct efx_nic *efx, bool local_node)
 {
-	cpumask_var_t thread_mask;
+	cpumask_var_t filter_mask;
 	unsigned int count;
 	int cpu;
 
-	if (rss_cpus) {
-		count = rss_cpus;
-	} else {
-		if (unlikely(!zalloc_cpumask_var(&thread_mask, GFP_KERNEL))) {
+	if (unlikely(!zalloc_cpumask_var(&filter_mask, GFP_KERNEL))) {
 		netif_warn(efx, probe, efx->net_dev,
 			   "RSS disabled due to allocation failure\n");
 		return 1;
 	}
 
+	cpumask_copy(filter_mask, cpu_online_mask);
+	if (local_node) {
+		int numa_node = pcibus_to_node(efx->pci_dev->bus);
+
+		cpumask_and(filter_mask, filter_mask, cpumask_of_node(numa_node));
+	}
+
 	count = 0;
-		for_each_online_cpu(cpu) {
-			if (!cpumask_test_cpu(cpu, thread_mask)) {
+	for_each_cpu(cpu, filter_mask) {
 		++count;
-				cpumask_or(thread_mask, thread_mask,
-					   topology_sibling_cpumask(cpu));
-			}
+		cpumask_andnot(filter_mask, filter_mask, topology_sibling_cpumask(cpu));
 	}
 
-		free_cpumask_var(thread_mask);
+	free_cpumask_var(filter_mask);
+
+	return count;
+}
+
+static unsigned int efx_wanted_parallelism(struct efx_nic *efx)
+{
+	unsigned int count;
+
+	if (rss_cpus) {
+		count = rss_cpus;
+	} else {
+		count = count_online_cores(efx, true);
+
+		/* If no online CPUs in local node, fallback to any online CPUs */
+		if (count == 0)
+			count = count_online_cores(efx, false);
 	}
 
 	if (count > EFX_MAX_RX_QUEUES) {