From 95bc2fb4c6c7d23db6dc54a3d49bdbadb13c392b Mon Sep 17 00:00:00 2001 From: Jacob Keller Date: Thu, 7 Sep 2017 08:05:52 -0400 Subject: [PATCH] i40e/i40evf: bundle more descriptors when allocating buffers Double the number of descriptors we'll bundle into one tail bump when receiving. Empirical testing has shown that we reduce CPU utilization and don't appear to reduce throughput or packet rate. 32 seems to be the sweet spot, as it's half the default polling budget, so we'd essentially reduce from 4 tail writes when polling down to 2. Increasing this up to 64 appears to have negative impacts as it may become possible that we don't bump the tail each time we get polled, which could cause a long delay between returning descriptors to the hardware. Signed-off-by: Jacob Keller Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/i40e/i40e_txrx.h | 2 +- drivers/net/ethernet/intel/i40evf/i40e_txrx.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h index c3156aa..ff57ae4 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h @@ -208,7 +208,7 @@ static inline bool i40e_test_staterr(union i40e_rx_desc *rx_desc, } /* How many Rx Buffers do we bundle into one write to the hardware ? */ -#define I40E_RX_BUFFER_WRITE 16 /* Must be power of 2 */ +#define I40E_RX_BUFFER_WRITE 32 /* Must be power of 2 */ #define I40E_RX_INCREMENT(r, i) \ do { \ (i)++; \ diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h index 8f9830d..8d26c85 100644 --- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h +++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h @@ -191,7 +191,7 @@ static inline bool i40e_test_staterr(union i40e_rx_desc *rx_desc, } /* How many Rx Buffers do we bundle into one write to the hardware ? */ -#define I40E_RX_BUFFER_WRITE 16 /* Must be power of 2 */ +#define I40E_RX_BUFFER_WRITE 32 /* Must be power of 2 */ #define I40E_RX_INCREMENT(r, i) \ do { \ (i)++; \ -- 2.7.4