[Intel-wired-lan] [next PATCH S17 03/11] i40e/i40evf: fix bug in throttle rate math
Catherine Sullivan
catherine.sullivan at intel.com
Mon Sep 28 18:16:52 UTC 2015
From: Jesse Brandeburg <jesse.brandeburg at intel.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.
Signed-off-by: Jesse Brandeburg <jesse.brandeburg at intel.com>
Change-ID: I5c20493103c295d6f201947bb908add7040b7c41
---
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 c023b12..24e8f6b 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -829,6 +829,7 @@ 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;
@@ -837,8 +838,14 @@ 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 3d2646b..3f4a595 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)
--
1.9.3
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