Commit 9a87c3fc authored by Dwip N. Banerjee's avatar Dwip N. Banerjee Committed by Jakub Kicinski
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ibmvnic: Ensure that device queue memory is cache-line aligned 



PCI bus slowdowns were observed on IBM VNIC devices as a result
of partial cache line writes and non-cache aligned full cache line writes.
Ensure that packet data buffers are cache-line aligned to avoid these
slowdowns.

Signed-off-by: default avatarDwip N. Banerjee <dnbanerg@us.ibm.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8ed589f3

drivers/net/ethernet/ibm/ibmvnic.c

+6 −3
Original line number Diff line number Diff line
@@ -498,7 +498,7 @@ static int reset_rx_pools(struct ibmvnic_adapter *adapter) 


		if (rx_pool->buff_size != buff_size) {

			free_long_term_buff(adapter, &rx_pool->long_term_buff);

			rx_pool->buff_size = buff_size;

			rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

			rc = alloc_long_term_buff(adapter,

						  &rx_pool->long_term_buff,

						  rx_pool->size *
@@ -592,7 +592,7 @@ static int init_rx_pools(struct net_device *netdev) 


		rx_pool->size = adapter->req_rx_add_entries_per_subcrq;

		rx_pool->index = i;

		rx_pool->buff_size = buff_size;

		rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

		rx_pool->active = 1;



		rx_pool->free_map = kcalloc(rx_pool->size, sizeof(int),
@@ -745,6 +745,7 @@ static int init_tx_pools(struct net_device *netdev) 
{

	struct ibmvnic_adapter *adapter = netdev_priv(netdev);

	int tx_subcrqs;

	u64 buff_size;

	int i, rc;



	tx_subcrqs = adapter->num_active_tx_scrqs;
@@ -761,9 +762,11 @@ static int init_tx_pools(struct net_device *netdev) 
	adapter->num_active_tx_pools = tx_subcrqs;



	for (i = 0; i < tx_subcrqs; i++) {

		buff_size = adapter->req_mtu + VLAN_HLEN;

		buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

		rc = init_one_tx_pool(netdev, &adapter->tx_pool[i],

				      adapter->req_tx_entries_per_subcrq,

				      adapter->req_mtu + VLAN_HLEN);

				      buff_size);

		if (rc) {

			release_tx_pools(adapter);

			return rc;

drivers/net/ethernet/ibm/ibmvnic.h

+5 −5
Original line number Diff line number Diff line
@@ -883,7 +883,7 @@ struct ibmvnic_sub_crq_queue { 
	atomic_t used;

	char name[32];

	u64 handle;

};

} ____cacheline_aligned;



struct ibmvnic_long_term_buff {

	unsigned char *buff;
@@ -907,7 +907,7 @@ struct ibmvnic_tx_pool { 
	struct ibmvnic_long_term_buff long_term_buff;

	int num_buffers;

	int buf_size;

};

} ____cacheline_aligned;



struct ibmvnic_rx_buff {

	struct sk_buff *skb;
@@ -928,7 +928,7 @@ struct ibmvnic_rx_pool { 
	int next_alloc;

	int active;

	struct ibmvnic_long_term_buff long_term_buff;

};

} ____cacheline_aligned;



struct ibmvnic_vpd {

	unsigned char *buff;
@@ -1015,8 +1015,8 @@ struct ibmvnic_adapter { 
	atomic_t running_cap_crqs;

	bool wait_capability;



	struct ibmvnic_sub_crq_queue **tx_scrq;

	struct ibmvnic_sub_crq_queue **rx_scrq;

	struct ibmvnic_sub_crq_queue **tx_scrq ____cacheline_aligned;

	struct ibmvnic_sub_crq_queue **rx_scrq ____cacheline_aligned;



	/* rx structs */

	struct napi_struct *napi;

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