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Subject[PATCH FIX net v2] net-e1000(e): Fix default interrupt throttle rate not set in NIC HW
Date
From: Ying Cai <ycai@google.com>

This change ensures that the itr/itr_setting adjustment logic is used,
even for the default/compiled-in value.

Context:
When we changed the default InterruptThrottleRate value from default
(3 = dynamic mode) to 8000 for example, only adapter->itr_setting
(which controls interrupt coalescing mode) was set to 8000, but
adapter->itr (which controls the value set in NIC register) was not
updated accordingly. So from ethtool, it seemed the interrupt
throttling is enabled at 8000 intr/s, but the NIC actually was
running in dynamic mode which has lower CPU efficiency especially
when throughput is not high.



Signed-off-by: David Decotigny <david.decotigny@google.com>
---
drivers/net/ethernet/intel/e1000/e1000_param.c | 81 +++++++++++--------
drivers/net/ethernet/intel/e1000e/param.c | 98 +++++++++++++-----------
2 files changed, 99 insertions(+), 80 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_param.c b/drivers/net/ethernet/intel/e1000/e1000_param.c
index 1301eba..595e462 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_param.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_param.c
@@ -173,7 +173,7 @@ E1000_PARAM(RxAbsIntDelay, "Receive Absolute Interrupt Delay");

/* Interrupt Throttle Rate (interrupts/sec)
*
- * Valid Range: 100-100000 (0=off, 1=dynamic, 3=dynamic conservative)
+ * Valid Range: 100-100000 or one of: 0=off, 1=dynamic, 3=dynamic conservative
*/
E1000_PARAM(InterruptThrottleRate, "Interrupt Throttling Rate");
#define DEFAULT_ITR 3
@@ -460,41 +460,54 @@ void __devinit e1000_check_options(struct e1000_adapter *adapter)
};

if (num_InterruptThrottleRate > bd) {
- adapter->itr = InterruptThrottleRate[bd];
- switch (adapter->itr) {
- case 0:
- e_dev_info("%s turned off\n", opt.name);
- break;
- case 1:
- e_dev_info("%s set to dynamic mode\n",
- opt.name);
- adapter->itr_setting = adapter->itr;
- adapter->itr = 20000;
- break;
- case 3:
- e_dev_info("%s set to dynamic conservative "
- "mode\n", opt.name);
- adapter->itr_setting = adapter->itr;
- adapter->itr = 20000;
- break;
- case 4:
- e_dev_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
- * used as control */
- adapter->itr_setting = adapter->itr & ~3;
- break;
- }
+ /* Make sure a message is printed for
+ * non-special values. And in case of an
+ * invalid option, display warning, use
+ * default and go through itr/itr_setting
+ * adjustment logic below */
+ if ((adapter->itr < 0 || adapter->itr > 4)
+ && e1000_validate_option(&adapter->itr, &opt,
+ adapter))
+ adapter->itr = opt.def;
} else {
- adapter->itr_setting = opt.def;
+ /* if no option specified, use default value
+ and go through the logic below to adjust
+ itr/itr_setting */
+ adapter->itr = opt.def;
+
+ /* Make sure a message is printed for
+ * non-special default values */
+ if (adapter->itr < 0 || adapter->itr > 4)
+ e_dev_info("%s set to default %d\n",
+ opt.name, adapter->itr);
+ }
+
+ adapter->itr_setting = adapter->itr;
+ switch (adapter->itr) {
+ case 0:
+ e_dev_info("%s turned off\n", opt.name);
+ break;
+ case 1:
+ e_dev_info("%s set to dynamic mode\n",
+ opt.name);
+ adapter->itr = 20000;
+ break;
+ case 3:
+ e_dev_info("%s set to dynamic conservative "
+ "mode\n", opt.name);
adapter->itr = 20000;
+ break;
+ case 4:
+ e_dev_info("%s set to simplified "
+ "(2000-8000) ints mode\n", opt.name);
+ break;
+ default:
+ /* save the setting, because the dynamic bits
+ * change itr.
+ * clear the lower two bits because they are
+ * used as control */
+ adapter->itr_setting &= ~3;
+ break;
}
}
{ /* Smart Power Down */
diff --git a/drivers/net/ethernet/intel/e1000e/param.c b/drivers/net/ethernet/intel/e1000e/param.c
index 20e93b0..41937e5 100644
--- a/drivers/net/ethernet/intel/e1000e/param.c
+++ b/drivers/net/ethernet/intel/e1000e/param.c
@@ -106,7 +106,7 @@ E1000_PARAM(RxAbsIntDelay, "Receive Absolute Interrupt Delay");
/*
* Interrupt Throttle Rate (interrupts/sec)
*
- * Valid Range: 100-100000 (0=off, 1=dynamic, 3=dynamic conservative)
+ * Valid Range: 100-100000 or one of: 0=off, 1=dynamic, 3=dynamic conservative
*/
E1000_PARAM(InterruptThrottleRate, "Interrupt Throttling Rate");
#define DEFAULT_ITR 3
@@ -335,53 +335,59 @@ void __devinit e1000e_check_options(struct e1000_adapter *adapter)

if (num_InterruptThrottleRate > bd) {
adapter->itr = InterruptThrottleRate[bd];
- switch (adapter->itr) {
- case 0:
- e_info("%s turned off\n", opt.name);
- break;
- case 1:
- e_info("%s set to dynamic mode\n", opt.name);
- adapter->itr_setting = adapter->itr;
- adapter->itr = 20000;
- break;
- case 3:
- e_info("%s set to dynamic conservative mode\n",
- opt.name);
- 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
- * change itr.
- */
- if (e1000_validate_option(&adapter->itr, &opt,
- adapter) &&
- (adapter->itr == 3)) {
- /*
- * In case of invalid user value,
- * default to conservative mode.
- */
- adapter->itr_setting = adapter->itr;
- adapter->itr = 20000;
- } else {
- /*
- * Clear the lower two bits because
- * they are used as control.
- */
- adapter->itr_setting =
- adapter->itr & ~3;
- }
- break;
- }
+
+ /* Make sure a message is printed for
+ * non-special values. And in case of an
+ * invalid option, display warning, use
+ * default and go through itr/itr_setting
+ * adjustment logic below */
+ if ((adapter->itr < 0 || adapter->itr > 4)
+ && e1000_validate_option(&adapter->itr, &opt,
+ adapter))
+ adapter->itr = opt.def;
} else {
- adapter->itr_setting = opt.def;
+ /* if no option specified, use default value
+ and go through the logic below to adjust
+ itr/itr_setting */
+ adapter->itr = opt.def;
+
+ /* Make sure a message is printed for
+ * non-special default values */
+ if (adapter->itr < 0 || adapter->itr > 4)
+ e_info("%s set to default %d\n",
+ opt.name, adapter->itr);
+ }
+
+
+
+ adapter->itr_setting = adapter->itr;
+ switch (adapter->itr) {
+ case 0:
+ e_info("%s turned off\n", opt.name);
+ break;
+ case 1:
+ e_info("%s set to dynamic mode\n", opt.name);
+ adapter->itr = 20000;
+ break;
+ case 3:
+ e_info("%s set to dynamic conservative mode\n",
+ opt.name);
adapter->itr = 20000;
+ break;
+ case 4:
+ e_info("%s set to simplified (2000-8000 ints) "
+ "mode\n", opt.name);
+ break;
+ default:
+ /*
+ * Save the setting, because the dynamic bits
+ * change itr.
+ *
+ * Clear the lower two bits because
+ * they are used as control.
+ */
+ adapter->itr_setting &= ~3;
+ break;
}
}
{ /* Interrupt Mode */
--
1.7.3.1


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