@@ -359,15 +359,19 @@ 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);
}
@@ -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
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> --- drivers/net/ethernet/sfc/ef100_tx.c | 8 ++++++-- drivers/net/ethernet/sfc/net_driver.h | 14 ++++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-)