e1000/e1000e: implement a simple interrupt moderation

Back before e1000-7.3.20, the e1000 driver had a simple algorithm that
managed interrupt moderation.  The driver was updated in 7.3.20 to
have the new "adaptive" interrupt moderation but we have customer
requests to redeploy the old way as an option.  This patch adds the
old functionality back.  The new functionality can be enabled via
module parameter or at runtime via ethtool.
Module parameter: (InterruptThrottleRate=4) to use this new
moderation method.
Ethtool method: ethtool -C ethX rx-usecs 4

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/e1000e/param.c b/drivers/net/e1000e/param.c
index f775a481063d..0f4077c3d538 100644
--- a/drivers/net/e1000e/param.c
+++ b/drivers/net/e1000e/param.c
@@ -351,6 +351,11 @@ void __devinit e1000e_check_options(struct e1000_adapter *adapter)
                                 adapter->itr_setting = adapter->itr;
                                 adapter->itr = 20000;
                                 break;
+                        case 4:
+                                e_info("%s set to simplified (2000-8000 ints) "
+                                       "mode\n", opt.name);
+                                adapter->itr_setting = 4;
+                                break;
                         default:
                                 /*
                                  * Save the setting, because the dynamic bits