sfc: Create one RX queue and interrupt per CPU package by default

Using multiple cores in the same package to handle received traffic
does not appear to provide a performance benefit.  Therefore use CPU
topology information to count CPU packages and use that as the default
number of RX queues and interrupts.  We rely on interrupt balancing to
spread the interrupts across packages.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 7b2a8186623244da041ec8baa683d075f021c232..45c72eebb3a7eb7b89d62aa92abef171a7676e7a 100644 (file)
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -19,6 +19,7 @@
 #include <linux/in.h>
 #include <linux/crc32.h>
 #include <linux/ethtool.h>
+#include <linux/topology.h>
 #include "net_driver.h"
 #include "gmii.h"
 #include "ethtool.h"
@@ -832,7 +833,23 @@ static void efx_probe_interrupts(struct efx_nic *efx)
        if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
                BUG_ON(!pci_find_capability(efx->pci_dev, PCI_CAP_ID_MSIX));
 
-               efx->rss_queues = rss_cpus ? rss_cpus : num_online_cpus();
+               if (rss_cpus == 0) {
+                       cpumask_t core_mask;
+                       int cpu;
+
+                       cpus_clear(core_mask);
+                       efx->rss_queues = 0;
+                       for_each_online_cpu(cpu) {
+                               if (!cpu_isset(cpu, core_mask)) {
+                                       ++efx->rss_queues;
+                                       cpus_or(core_mask, core_mask,
+                                               topology_core_siblings(cpu));
+                               }
+                       }
+               } else {
+                       efx->rss_queues = rss_cpus;
+               }
+
                efx->rss_queues = min(efx->rss_queues, max_channel + 1);
                efx->rss_queues = min(efx->rss_queues, EFX_MAX_CHANNELS);