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Date: Mon, 19 Oct 2015 15:49:21 -0700
From: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To: davem@...emloft.net
Cc: Jesse Brandeburg <jesse.brandeburg@...el.com>,
netdev@...r.kernel.org, nhorman@...hat.com, sassmann@...hat.com,
jogreene@...hat.com, Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next v2 07/17] i40e/i40evf: fix bug in throttle rate math
From: Jesse Brandeburg <jesse.brandeburg@...el.com>
The driver was using a value expressed in 2us increments
for the divisor to figure out our bytes/usec values.
Fix the usecs variable to contain a value in microseconds.
Change-ID: I5c20493103c295d6f201947bb908add7040b7c41
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 9 ++++++++-
drivers/net/ethernet/intel/i40evf/i40e_txrx.c | 9 ++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 889d25d..c96e581 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -830,6 +830,7 @@ static bool i40e_set_new_dynamic_itr(struct i40e_ring_container *rc)
enum i40e_latency_range new_latency_range = rc->latency_range;
u32 new_itr = rc->itr;
int bytes_per_int;
+ int usecs;
if (rc->total_packets == 0 || !rc->itr)
return false;
@@ -838,8 +839,14 @@ static bool i40e_set_new_dynamic_itr(struct i40e_ring_container *rc)
* 0-10MB/s lowest (100000 ints/s)
* 10-20MB/s low (20000 ints/s)
* 20-1249MB/s bulk (8000 ints/s)
+ *
+ * The math works out because the divisor is in 10^(-6) which
+ * turns the bytes/us input value into MB/s values, but
+ * make sure to use usecs, as the register values written
+ * are in 2 usec increments in the ITR registers.
*/
- bytes_per_int = rc->total_bytes / rc->itr;
+ usecs = (rc->itr << 1);
+ bytes_per_int = rc->total_bytes / usecs;
switch (new_latency_range) {
case I40E_LOWEST_LATENCY:
if (bytes_per_int > 10)
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index 597e096..7d98042 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -333,6 +333,7 @@ static bool i40e_set_new_dynamic_itr(struct i40e_ring_container *rc)
enum i40e_latency_range new_latency_range = rc->latency_range;
u32 new_itr = rc->itr;
int bytes_per_int;
+ int usecs;
if (rc->total_packets == 0 || !rc->itr)
return false;
@@ -341,8 +342,14 @@ static bool i40e_set_new_dynamic_itr(struct i40e_ring_container *rc)
* 0-10MB/s lowest (100000 ints/s)
* 10-20MB/s low (20000 ints/s)
* 20-1249MB/s bulk (8000 ints/s)
+ *
+ * The math works out because the divisor is in 10^(-6) which
+ * turns the bytes/us input value into MB/s values, but
+ * make sure to use usecs, as the register values written
+ * are in 2 usec increments in the ITR registers.
*/
- bytes_per_int = rc->total_bytes / rc->itr;
+ usecs = (rc->itr << 1);
+ bytes_per_int = rc->total_bytes / usecs;
switch (new_latency_range) {
case I40E_LOWEST_LATENCY:
if (bytes_per_int > 10)
--
2.4.3
--
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