sfc: Move CPU counting for RSS into a separate function, efx_wanted_rx_queues()
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 9f1ac3a..487df94 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -819,38 +819,48 @@
pci_disable_device(efx->pci_dev);
}
-/* Probe the number and type of interrupts we are able to obtain. */
+/* Get number of RX queues wanted. Return number of online CPU
+ * packages in the expectation that an IRQ balancer will spread
+ * interrupts across them. */
+static int efx_wanted_rx_queues(void)
+{
+ cpumask_t core_mask;
+ int count;
+ int cpu;
+
+ cpus_clear(core_mask);
+ count = 0;
+ for_each_online_cpu(cpu) {
+ if (!cpu_isset(cpu, core_mask)) {
+ ++count;
+ cpus_or(core_mask, core_mask,
+ topology_core_siblings(cpu));
+ }
+ }
+
+ return count;
+}
+
+/* Probe the number and type of interrupts we are able to obtain, and
+ * the resulting numbers of channels and RX queues.
+ */
static void efx_probe_interrupts(struct efx_nic *efx)
{
- int max_channel = efx->type->phys_addr_channels - 1;
- struct msix_entry xentries[EFX_MAX_CHANNELS];
+ int max_channels =
+ min_t(int, efx->type->phys_addr_channels, EFX_MAX_CHANNELS);
int rc, i;
if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
- BUG_ON(!pci_find_capability(efx->pci_dev, PCI_CAP_ID_MSIX));
+ struct msix_entry xentries[EFX_MAX_CHANNELS];
+ int wanted_ints;
- if (rss_cpus == 0) {
- cpumask_t core_mask;
- int cpu;
+ /* We want one RX queue and interrupt per CPU package
+ * (or as specified by the rss_cpus module parameter).
+ * We will need one channel per interrupt.
+ */
+ wanted_ints = rss_cpus ? rss_cpus : efx_wanted_rx_queues();
+ efx->rss_queues = min(wanted_ints, max_channels);
- 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);
-
- /* Request maximum number of MSI interrupts, and fill out
- * the channel interrupt information the allowed allocation */
for (i = 0; i < efx->rss_queues; i++)
xentries[i].entry = i;
rc = pci_enable_msix(efx->pci_dev, xentries, efx->rss_queues);