netdev - [PATCH net 4/7] net: aquantia: Add aq_tx_clean_budget and valid budget handling logic

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Message-Id: <33a3d54c44403ea0f56d4881341cb94cd22e08fc.1521192913.git.igor.russkikh@aquantia.com>
Date:   Fri, 16 Mar 2018 13:53:47 +0300
From:   Igor Russkikh <igor.russkikh@...antia.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, David Arcari <darcari@...hat.com>,
        Pavel Belous <pavel.belous@...antia.com>,
        Igor Russkikh <igor.russkikh@...antia.com>
Subject: [PATCH net 4/7] net: aquantia: Add aq_tx_clean_budget and valid budget handling logic

We should report to napi full budget only when we have more job to do.
Before this fix, on any tx queue cleanup we forced napi to do poll again.
Thats a waste of cpu resources and caused storming with napi polls when
there was at least one tx on each interrupt.

With this fix we report full budget only when there is more job on TX
to do. Or, as before, when rx budget was fully consumed.

Signed-off-by: Igor Russkikh <igor.russkikh@...antia.com>
---
 drivers/net/ethernet/aquantia/atlantic/aq_nic.c  | 4 ++++
 drivers/net/ethernet/aquantia/atlantic/aq_nic.h  | 2 ++
 drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 7 +++++--
 drivers/net/ethernet/aquantia/atlantic/aq_ring.h | 2 +-
 drivers/net/ethernet/aquantia/atlantic/aq_vec.c  | 7 +++----
 5 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
index ebbaf63..5723f2c 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
@@ -36,6 +36,10 @@ static unsigned int aq_itr_rx;
 module_param_named(aq_itr_rx, aq_itr_rx, uint, 0644);
 MODULE_PARM_DESC(aq_itr_rx, "RX interrupt throttle rate");
 
+unsigned aq_tx_clean_budget = 256;
+module_param_named(aq_tx_clean_budget, aq_tx_clean_budget, uint, 0644);
+MODULE_PARM_DESC(aq_tx_clean_budget, "Maximum descriptors to cleanup on TX at once");
+
 static void aq_nic_update_ndev_stats(struct aq_nic_s *self);
 
 static void aq_nic_rss_init(struct aq_nic_s *self, unsigned int num_rss_queues)
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_nic.h b/drivers/net/ethernet/aquantia/atlantic/aq_nic.h
index d16b0f1..2b689b7 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.h
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.h
@@ -87,6 +87,8 @@ static inline struct device *aq_nic_get_dev(struct aq_nic_s *self)
 	return self->ndev->dev.parent;
 }
 
+extern unsigned aq_tx_clean_budget;
+
 void aq_nic_ndev_init(struct aq_nic_s *self);
 struct aq_nic_s *aq_nic_alloc_hot(struct net_device *ndev);
 void aq_nic_set_tx_ring(struct aq_nic_s *self, unsigned int idx,
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 0be6a11..64a6de6 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -136,11 +136,12 @@ void aq_ring_queue_stop(struct aq_ring_s *ring)
 		netif_stop_subqueue(ndev, ring->idx);
 }
 
-void aq_ring_tx_clean(struct aq_ring_s *self)
+bool aq_ring_tx_clean(struct aq_ring_s *self)
 {
 	struct device *dev = aq_nic_get_dev(self->aq_nic);
+	unsigned int budget = aq_tx_clean_budget;
 
-	for (; self->sw_head != self->hw_head;
+	for (; self->sw_head != self->hw_head && budget--;
 		self->sw_head = aq_ring_next_dx(self, self->sw_head)) {
 		struct aq_ring_buff_s *buff = &self->buff_ring[self->sw_head];
 
@@ -167,6 +168,8 @@ void aq_ring_tx_clean(struct aq_ring_s *self)
 		buff->pa = 0U;
 		buff->eop_index = 0xffffU;
 	}
+
+	return !!budget;
 }
 
 #define AQ_SKB_ALIGN SKB_DATA_ALIGN(sizeof(struct skb_shared_info))
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.h b/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
index 965fae0..ac1329f 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
@@ -153,7 +153,7 @@ void aq_ring_free(struct aq_ring_s *self);
 void aq_ring_update_queue_state(struct aq_ring_s *ring);
 void aq_ring_queue_wake(struct aq_ring_s *ring);
 void aq_ring_queue_stop(struct aq_ring_s *ring);
-void aq_ring_tx_clean(struct aq_ring_s *self);
+bool aq_ring_tx_clean(struct aq_ring_s *self);
 int aq_ring_rx_clean(struct aq_ring_s *self,
 		     struct napi_struct *napi,
 		     int *work_done,
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_vec.c b/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
index f890b8a..9528507 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_vec.c
@@ -40,7 +40,7 @@ static int aq_vec_poll(struct napi_struct *napi, int budget)
 	int err = 0;
 	unsigned int i = 0U;
 	unsigned int sw_tail_old = 0U;
-	bool was_tx_cleaned = false;
+	bool was_tx_cleaned = true;
 
 	if (!self) {
 		err = -EINVAL;
@@ -57,9 +57,8 @@ static int aq_vec_poll(struct napi_struct *napi, int budget)
 
 			if (ring[AQ_VEC_TX_ID].sw_head !=
 			    ring[AQ_VEC_TX_ID].hw_head) {
-				aq_ring_tx_clean(&ring[AQ_VEC_TX_ID]);
+				was_tx_cleaned = aq_ring_tx_clean(&ring[AQ_VEC_TX_ID]);
 				aq_ring_update_queue_state(&ring[AQ_VEC_TX_ID]);
-				was_tx_cleaned = true;
 			}
 
 			err = self->aq_hw_ops->hw_ring_rx_receive(self->aq_hw,
@@ -90,7 +89,7 @@ static int aq_vec_poll(struct napi_struct *napi, int budget)
 			}
 		}
 
-		if (was_tx_cleaned)
+		if (!was_tx_cleaned)
 			work_done = budget;
 
 		if (work_done < budget) {
-- 
2.7.4