From 05785adf6e570a068adf0502b61fe2b521d7f0ca Mon Sep 17 00:00:00 2001 From: Arthur Kiyanovski Date: Thu, 19 Dec 2019 17:40:55 +0200 Subject: net: ena: fix default tx interrupt moderation interval Current default non-adaptive tx interrupt moderation interval is 196 us. This value is too high and might cause the tx queue to fill up. In this commit we set the default non-adaptive tx interrupt moderation interval to 64 us in order to: 1. Reduce the probability of the queue filling-up (when compared to the current default value of 196 us). 2. Reduce unnecessary tx interrupt overhead (which happens if we set the default tx interval to 0). We determined experimentally that 64 us is an optimal value that reduces interrupt rate by more than 20% without affecting performance. Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)") Signed-off-by: Arthur Kiyanovski Signed-off-by: David S. Miller --- drivers/net/ethernet/amazon/ena/ena_com.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h index 7c941eba0bc9..0ce37d54ed10 100644 --- a/drivers/net/ethernet/amazon/ena/ena_com.h +++ b/drivers/net/ethernet/amazon/ena/ena_com.h @@ -72,7 +72,7 @@ /*****************************************************************************/ /* ENA adaptive interrupt moderation settings */ -#define ENA_INTR_INITIAL_TX_INTERVAL_USECS 196 +#define ENA_INTR_INITIAL_TX_INTERVAL_USECS 64 #define ENA_INTR_INITIAL_RX_INTERVAL_USECS 0 #define ENA_DEFAULT_INTR_DELAY_RESOLUTION 1 -- cgit v1.2.3 From 41c53caa5a61ebc9221b71cc37f4a90549f1121d Mon Sep 17 00:00:00 2001 From: Arthur Kiyanovski Date: Thu, 19 Dec 2019 17:40:56 +0200 Subject: net: ena: fix issues in setting interrupt moderation params in ethtool Issue 1: -------- Reproduction steps: 1. sudo ethtool -C eth0 rx-usecs 128 2. sudo ethtool -C eth0 adaptive-rx on 3. sudo ethtool -C eth0 adaptive-rx off 4. ethtool -c eth0 expected output: rx-usecs 128 actual output: rx-usecs 0 Reason for issue: In stage 3, ethtool userspace calls first the ena_get_coalesce() handler to get the current value of all properties, and then the ena_set_coalesce() handler. When ena_get_coalesce() is called the adaptive interrupt moderation is still on. There is an if in the code that returns the rx_coalesce_usecs only if the adaptive interrupt moderation is off. And since it is still on, rx_coalesce_usecs is not set, meaning it stays 0. Solution to issue: Remove this if static interrupt moderation intervals have nothing to do with dynamic ones. Issue 2: -------- Reproduction steps: 1. sudo ethtool -C eth0 adaptive-rx on 2. sudo ethtool -C eth0 rx-usecs 128 3. ethtool -c eth0 expected output: rx-usecs 128 actual output: rx-usecs 0 Reason for issue: In stage 2, when ena_set_coalesce() is called, the handler tests if rx adaptive interrupt moderation is on, and if it is, it returns before getting to the part in the function that sets the rx non-adaptive interrupt moderation interval. Solution to issue: Remove the return from the function when rx adaptive interrupt moderation is on. Also cleaned up the fixed code in ena_set_coalesce by grouping together adaptive interrupt moderation toggling, and using && instead of nested ifs. Fixes: b3db86dc4b82 ("net: ena: reimplement set/get_coalesce()") Fixes: 0eda847953d8 ("net: ena: fix retrieval of nonadaptive interrupt moderation intervals") Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)") Signed-off-by: Arthur Kiyanovski Signed-off-by: David S. Miller --- drivers/net/ethernet/amazon/ena/ena_ethtool.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) (limited to 'drivers') diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c index a3250dcf7d53..fc96c66b44cb 100644 --- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c +++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c @@ -315,10 +315,9 @@ static int ena_get_coalesce(struct net_device *net_dev, ena_com_get_nonadaptive_moderation_interval_tx(ena_dev) * ena_dev->intr_delay_resolution; - if (!ena_com_get_adaptive_moderation_enabled(ena_dev)) - coalesce->rx_coalesce_usecs = - ena_com_get_nonadaptive_moderation_interval_rx(ena_dev) - * ena_dev->intr_delay_resolution; + coalesce->rx_coalesce_usecs = + ena_com_get_nonadaptive_moderation_interval_rx(ena_dev) + * ena_dev->intr_delay_resolution; coalesce->use_adaptive_rx_coalesce = ena_com_get_adaptive_moderation_enabled(ena_dev); @@ -367,12 +366,6 @@ static int ena_set_coalesce(struct net_device *net_dev, ena_update_tx_rings_intr_moderation(adapter); - if (coalesce->use_adaptive_rx_coalesce) { - if (!ena_com_get_adaptive_moderation_enabled(ena_dev)) - ena_com_enable_adaptive_moderation(ena_dev); - return 0; - } - rc = ena_com_update_nonadaptive_moderation_interval_rx(ena_dev, coalesce->rx_coalesce_usecs); if (rc) @@ -380,10 +373,13 @@ static int ena_set_coalesce(struct net_device *net_dev, ena_update_rx_rings_intr_moderation(adapter); - if (!coalesce->use_adaptive_rx_coalesce) { - if (ena_com_get_adaptive_moderation_enabled(ena_dev)) - ena_com_disable_adaptive_moderation(ena_dev); - } + if (coalesce->use_adaptive_rx_coalesce && + !ena_com_get_adaptive_moderation_enabled(ena_dev)) + ena_com_enable_adaptive_moderation(ena_dev); + + if (!coalesce->use_adaptive_rx_coalesce && + ena_com_get_adaptive_moderation_enabled(ena_dev)) + ena_com_disable_adaptive_moderation(ena_dev); return 0; } -- cgit v1.2.3