diff mbox series

[net] cxgb4: fix Txq restart check during backpressure

Message ID 1584639490-27208-2-git-send-email-rahul.lakkireddy@chelsio.com
State Accepted
Delegated to: David Miller
Headers show
Series [net] cxgb4: fix Txq restart check during backpressure | expand

Commit Message

Rahul Lakkireddy March 19, 2020, 5:38 p.m. UTC 
Driver reclaims descriptors in much smaller batches, even if hardware
indicates more to reclaim, during backpressure. So, fix the check to
restart the Txq during backpressure, by looking at how many
descriptors hardware had indicated to reclaim, and not on how many
descriptors that driver had actually reclaimed. Once the Txq is
restarted, driver will reclaim even more descriptors when Tx path
is entered again.

Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
---
 drivers/net/ethernet/chelsio/cxgb4/sge.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

David Miller March 20, 2020, 4:30 a.m. UTC | #1 
From: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Date: Thu, 19 Mar 2020 23:08:10 +0530

> Driver reclaims descriptors in much smaller batches, even if hardware
> indicates more to reclaim, during backpressure. So, fix the check to
> restart the Txq during backpressure, by looking at how many
> descriptors hardware had indicated to reclaim, and not on how many
> descriptors that driver had actually reclaimed. Once the Txq is
> restarted, driver will reclaim even more descriptors when Tx path
> is entered again.
> 
> Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer")
> Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>

Applied, thanks.
diff mbox series

Patch

diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c b/drivers/net/ethernet/chelsio/cxgb4/sge.c
index c816837fbd85..cab3d17e0e1a 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c
@@ -1307,8 +1307,9 @@  static inline void *write_tso_wr(struct adapter *adap, struct sk_buff *skb,
 int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq,
 				 int maxreclaim)
 {
+	unsigned int reclaimed, hw_cidx;
 	struct sge_txq *q = &eq->q;
-	unsigned int reclaimed;
+	int hw_in_use;
 
 	if (!q->in_use || !__netif_tx_trylock(eq->txq))
 		return 0;
@@ -1316,12 +1317,17 @@  int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq,
 	/* Reclaim pending completed TX Descriptors. */
 	reclaimed = reclaim_completed_tx(adap, &eq->q, maxreclaim, true);
 
+	hw_cidx = ntohs(READ_ONCE(q->stat->cidx));
+	hw_in_use = q->pidx - hw_cidx;
+	if (hw_in_use < 0)
+		hw_in_use += q->size;
+
 	/* If the TX Queue is currently stopped and there's now more than half
 	 * the queue available, restart it.  Otherwise bail out since the rest
 	 * of what we want do here is with the possibility of shipping any
 	 * currently buffered Coalesced TX Work Request.
 	 */
-	if (netif_tx_queue_stopped(eq->txq) && txq_avail(q) > (q->size / 2)) {
+	if (netif_tx_queue_stopped(eq->txq) && hw_in_use < (q->size / 2)) {
 		netif_tx_wake_queue(eq->txq);
 		eq->q.restarts++;
 	}