From: Andy Gospodarek <gospo@redhat.com>
Date: Thu, 3 Jun 2010 02:55:17 -0400
Subject: [net] e1000/e1000e: implement simple interrupt moderation
Message-id: <20100603025517.GQ23636@gospo.rdu.redhat.com>
Patchwork-id: 25942
O-Subject: Re: [PATCH RHEL5.6 v2] e1000/e1000e: implement a simple interrupt
	moderation
Bugzilla: 586416
RH-Acked-by: David S. Miller <davem@redhat.com>
RH-Acked-by: Dean Nelson <dnelson@redhat.com>
RH-Acked-by: Stefan Assmann <sassmann@redhat.com>

Backport of upstream commit listed below that will bring back the
ability to use a more simple algorithm for interrupt modulation.  This
does not change the default, it only makes the old option available via
ethtool.

	commit eab2abf5826b78b126826cc70e564c44816396da
	Author: Jesse Brandeburg <jesse.brandeburg@intel.com>
	Date:   Tue May 4 22:26:03 2010 +0000

	    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

A similar version of this backport (minus 2 additional checks) was
reported as working, so this version should work as expected.

This will resolve the request made in RHBZ 586416.


diff --git a/drivers/net/e1000/e1000_ethtool.c b/drivers/net/e1000/e1000_ethtool.c
index 8161476..b767b0e 100644
--- a/drivers/net/e1000/e1000_ethtool.c
+++ b/drivers/net/e1000/e1000_ethtool.c
@@ -1907,7 +1907,7 @@ static int e1000_get_coalesce(struct net_device *netdev,
 	if (adapter->hw.mac_type < e1000_82545)
 		return -EOPNOTSUPP;
 
-	if (adapter->itr_setting <= 3)
+	if (adapter->itr_setting <= 4)
 		ec->rx_coalesce_usecs = adapter->itr_setting;
 	else
 		ec->rx_coalesce_usecs = 1000000 / adapter->itr_setting;
@@ -1925,12 +1925,14 @@ static int e1000_set_coalesce(struct net_device *netdev,
 		return -EOPNOTSUPP;
 
 	if ((ec->rx_coalesce_usecs > E1000_MAX_ITR_USECS) ||
-	    ((ec->rx_coalesce_usecs > 3) &&
+	    ((ec->rx_coalesce_usecs > 4) &&
 	     (ec->rx_coalesce_usecs < E1000_MIN_ITR_USECS)) ||
 	    (ec->rx_coalesce_usecs == 2))
 		return -EINVAL;
 
-	if (ec->rx_coalesce_usecs <= 3) {
+	if (ec->rx_coalesce_usecs == 4) {
+		adapter->itr = adapter->itr_setting = 4;
+	} else if (ec->rx_coalesce_usecs <= 3) {
 		adapter->itr = 20000;
 		adapter->itr_setting = ec->rx_coalesce_usecs;
 	} else {
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 578494d..804eeda 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -37,7 +37,7 @@ static char e1000_driver_string[] = "Intel(R) PRO/1000 Network Driver";
 #else
 #define DRIVERNAPI "-NAPI"
 #endif
-#define DRV_VERSION "7.3.21-k4"DRIVERNAPI
+#define DRV_VERSION "7.3.21-k4.1"DRIVERNAPI
 const char e1000_driver_version[] = DRV_VERSION;
 static const char e1000_copyright[] = "Copyright (c) 1999-2006 Intel Corporation.";
 
@@ -2865,6 +2865,22 @@ link_up:
 		}
 	}
 
+	/* Simple mode for Interrupt Throttle Rate (ITR) */
+	if (hw->mac_type >= e1000_82540 && adapter->itr_setting == 4) {
+		/*
+		 * Symmetric Tx/Rx gets a reduced ITR=2000;
+		 * Total asymmetrical Tx or Rx gets ITR=8000;
+		 * everyone else is between 2000-8000.
+		 */
+		u32 goc = (adapter->gotcl + adapter->gorcl) / 10000;
+		u32 dif = (adapter->gotcl > adapter->gorcl ?
+			    adapter->gotcl - adapter->gorcl :
+			    adapter->gorcl - adapter->gotcl) / 10000;
+		u32 itr = goc > 0 ? (dif * 6000 / goc + 2000) : 8000;
+
+		ew32(ITR, 1000000000 / (itr * 256));
+	}
+
 	/* Cause software interrupt to ensure rx ring is cleaned */
 	ew32(ICS, E1000_ICS_RXDMT0);
 
diff --git a/drivers/net/e1000/e1000_param.c b/drivers/net/e1000/e1000_param.c
index 67f815d..54643ce 100644
--- a/drivers/net/e1000/e1000_param.c
+++ b/drivers/net/e1000/e1000_param.c
@@ -523,11 +523,18 @@ void __devinit e1000_check_options(struct e1000_adapter *adapter)
 				adapter->itr_setting = adapter->itr;
 				adapter->itr = 20000;
 				break;
+			case 4:
+				DPRINTK(PROBE, INFO,
+					"%s set to simplified "
+				        "(2000-8000) ints mode\n", opt.name);
+				adapter->itr_setting = adapter->itr;
+				break;
 			default:
 				e1000_validate_option(&adapter->itr, &opt,
 				        adapter);
-				/* save the setting, because the dynamic bits change itr */
-				/* clear the lower two bits because they are
+				/* save the setting, because the dynamic bits
+				 * change itr.
+				 * clear the lower two bits because they are
 				 * used as control */
 				adapter->itr_setting = adapter->itr & ~3;
 				break;
diff --git a/drivers/net/e1000e/ethtool.c b/drivers/net/e1000e/ethtool.c
index 147d681..5b097db 100644
--- a/drivers/net/e1000e/ethtool.c
+++ b/drivers/net/e1000e/ethtool.c
@@ -1844,7 +1844,7 @@ static int e1000_get_coalesce(struct net_device *netdev,
 {
 	struct e1000_adapter *adapter = netdev_priv(netdev);
 
-	if (adapter->itr_setting <= 3)
+	if (adapter->itr_setting <= 4)
 		ec->rx_coalesce_usecs = adapter->itr_setting;
 	else
 		ec->rx_coalesce_usecs = 1000000 / adapter->itr_setting;
@@ -1859,12 +1859,14 @@ static int e1000_set_coalesce(struct net_device *netdev,
 	struct e1000_hw *hw = &adapter->hw;
 
 	if ((ec->rx_coalesce_usecs > E1000_MAX_ITR_USECS) ||
-	    ((ec->rx_coalesce_usecs > 3) &&
+	    ((ec->rx_coalesce_usecs > 4) &&
 	     (ec->rx_coalesce_usecs < E1000_MIN_ITR_USECS)) ||
 	    (ec->rx_coalesce_usecs == 2))
 		return -EINVAL;
 
-	if (ec->rx_coalesce_usecs <= 3) {
+	if (ec->rx_coalesce_usecs == 4) {
+		adapter->itr = adapter->itr_setting = 4;
+	} else if (ec->rx_coalesce_usecs <= 3) {
 		adapter->itr = 20000;
 		adapter->itr_setting = ec->rx_coalesce_usecs;
 	} else {
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index cbc17ec..5c858f3 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -48,7 +48,7 @@
 
 #include "e1000.h"
 
-#define DRV_VERSION "1.0.2-k3"
+#define DRV_VERSION "1.0.2-k3.1"
 char e1000e_driver_name[] = "e1000e";
 const char e1000e_driver_version[] = DRV_VERSION;
 
@@ -3774,6 +3774,22 @@ link_up:
 		}
 	}
 
+	/* Simple mode for Interrupt Throttle Rate (ITR) */
+	if (adapter->itr_setting == 4) {
+		/*
+		 * Symmetric Tx/Rx gets a reduced ITR=2000;
+		 * Total asymmetrical Tx or Rx gets ITR=8000;
+		 * everyone else is between 2000-8000.
+		 */
+		u32 goc = (adapter->gotc + adapter->gorc) / 10000;
+		u32 dif = (adapter->gotc > adapter->gorc ?
+			    adapter->gotc - adapter->gorc :
+			    adapter->gorc - adapter->gotc) / 10000;
+		u32 itr = goc > 0 ? (dif * 6000 / goc + 2000) : 8000;
+
+		ew32(ITR, 1000000000 / (itr * 256));
+	}
+
 	/* Cause software interrupt to ensure Rx ring is cleaned */
 	if (adapter->msix_entries)
 		ew32(ICS, adapter->rx_ring->ims_val);
diff --git a/drivers/net/e1000e/param.c b/drivers/net/e1000e/param.c
index 1342e0b..e3bdcb1 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