From 51cc6d9fccde27310b7dfba2be268ff5b8dcf52d Mon Sep 17 00:00:00 2001 From: Jesse Brandeburg Date: Mon, 28 Sep 2015 14:16:52 -0400 Subject: [PATCH] i40e/i40evf: fix bug in throttle rate math 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 Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- 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 889d25d6fde2..c96e581cc2b7 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 597e0964c232..7d98042338e0 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) -- 2.30.2