diff options
| author | Edward Cree <ecree@solarflare.com> | 2020-09-03 22:34:57 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-09-05 12:21:40 -0700 |
| commit | 5374d6024cd47e028f96a382104b2653f010b430 (patch) | |
| tree | 0ef043f9bf31093acc8660897bb0a258628c7e3d | |
| parent | 8cb2675634ab8ec7986aa9dfe1a7a934872ef51d (diff) | |
sfc: use tx_queue->old_read_count in EF100 TX path
As in the Siena/EF10 case, it minimises cacheline ping-pong between
the TX and completion paths.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/sfc/ef100_tx.c | 8 | ||||
| -rw-r--r-- | drivers/net/ethernet/sfc/net_driver.h | 14 |
2 files changed, 20 insertions, 2 deletions
diff --git a/drivers/net/ethernet/sfc/ef100_tx.c b/drivers/net/ethernet/sfc/ef100_tx.c index ce1b462efd17..078c7ec2a70e 100644 --- a/drivers/net/ethernet/sfc/ef100_tx.c +++ b/drivers/net/ethernet/sfc/ef100_tx.c @@ -360,15 +360,19 @@ int ef100_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb) goto err; ef100_tx_make_descriptors(tx_queue, skb, segments); - fill_level = efx_channel_tx_fill_level(tx_queue->channel); + fill_level = efx_channel_tx_old_fill_level(tx_queue->channel); if (fill_level > efx->txq_stop_thresh) { + struct efx_tx_queue *txq2; + netif_tx_stop_queue(tx_queue->core_txq); /* Re-read after a memory barrier in case we've raced with * the completion path. Otherwise there's a danger we'll never * restart the queue if all completions have just happened. */ smp_mb(); - fill_level = efx_channel_tx_fill_level(tx_queue->channel); + efx_for_each_channel_tx_queue(txq2, tx_queue->channel) + txq2->old_read_count = READ_ONCE(txq2->read_count); + fill_level = efx_channel_tx_old_fill_level(tx_queue->channel); if (fill_level < efx->txq_stop_thresh) netif_tx_start_queue(tx_queue->core_txq); } diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h index adc138f9d15f..366e649fa869 100644 --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -1692,6 +1692,20 @@ efx_channel_tx_fill_level(struct efx_channel *channel) return fill_level; } +/* Conservative approximation of efx_channel_tx_fill_level using cached value */ +static inline unsigned int +efx_channel_tx_old_fill_level(struct efx_channel *channel) +{ + struct efx_tx_queue *tx_queue; + unsigned int fill_level = 0; + + efx_for_each_channel_tx_queue(tx_queue, channel) + fill_level = max(fill_level, + tx_queue->insert_count - tx_queue->old_read_count); + + return fill_level; +} + /* Get all supported features. * If a feature is not fixed, it is present in hw_features. * If a feature is fixed, it does not present in hw_features, but |