i40e/i40evf: adjust interrupt throttle less frequently
The adaptive ITR (interrupt throttle rate) algorithm was adjusting
the hardware's interrupt rate too frequently. This caused a lot
of variation in the interrupt rate for fairly constant workloads.
Change the code to have a counter and adjust only once every N
number of interrupts.
Change-ID: I0460f1f86571037484eca5aca36ac4d889cb8389
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index b7818be..7c2b2e8 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -577,6 +577,8 @@
struct rcu_head rcu; /* to avoid race with update stats on free */
char name[I40E_INT_NAME_STR_LEN];
bool arm_wb_state;
+#define ITR_COUNTDOWN_START 100
+ u8 itr_countdown; /* when 0 should adjust ITR */
} ____cacheline_internodealigned_in_smp;
/* lan device */