Commit 44fbc1b6 authored by Nick Child's avatar Nick Child Committed by David S. Miller
Browse files

ibmvnic: Assign IRQ affinity hints to device queues 



Assign affinity hints to ibmvnic device queue interrupts.
Affinity hints are assigned and removed during sub-crq init and
teardown, respectively. This update should improve latency if
utilized as interrupt lines and processing are more equally
distributed among CPU's. This implementation is based on the
virtio_net driver.

Signed-off-by: default avatarThomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: default avatarDany Madden <drt@linux.ibm.com>
Signed-off-by: default avatarNick Child <nnac123@linux.ibm.com>
Reviewed-by: default avatarRick Lindsley <ricklind@linux.ibm.com>
Reviewed-by: default avatarHaren Myneni <haren@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e384cf35

drivers/net/ethernet/ibm/ibmvnic.c

+140 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ 
#include <linux/workqueue.h>

#include <linux/if_vlan.h>

#include <linux/utsname.h>

#include <linux/cpu.h>



#include "ibmvnic.h"
@@ -171,6 +172,132 @@ static int send_version_xchg(struct ibmvnic_adapter *adapter) 
	return ibmvnic_send_crq(adapter, &crq);

}



static void ibmvnic_clean_queue_affinity(struct ibmvnic_adapter *adapter,

					 struct ibmvnic_sub_crq_queue *queue)

{

	if (!(queue && queue->irq))

		return;



	cpumask_clear(queue->affinity_mask);



	if (irq_set_affinity_and_hint(queue->irq, NULL))

		netdev_warn(adapter->netdev,

			    "%s: Clear affinity failed, queue addr = %p, IRQ = %d\n",

			    __func__, queue, queue->irq);

}



static void ibmvnic_clean_affinity(struct ibmvnic_adapter *adapter)

{

	struct ibmvnic_sub_crq_queue **rxqs;

	struct ibmvnic_sub_crq_queue **txqs;

	int num_rxqs, num_txqs;

	int rc, i;



	rc = 0;

	rxqs = adapter->rx_scrq;

	txqs = adapter->tx_scrq;

	num_txqs = adapter->num_active_tx_scrqs;

	num_rxqs = adapter->num_active_rx_scrqs;



	netdev_dbg(adapter->netdev, "%s: Cleaning irq affinity hints", __func__);

	if (txqs) {

		for (i = 0; i < num_txqs; i++)

			ibmvnic_clean_queue_affinity(adapter, txqs[i]);

	}

	if (rxqs) {

		for (i = 0; i < num_rxqs; i++)

			ibmvnic_clean_queue_affinity(adapter, rxqs[i]);

	}

}



static int ibmvnic_set_queue_affinity(struct ibmvnic_sub_crq_queue *queue,

				      unsigned int *cpu, int *stragglers,

				      int stride)

{

	cpumask_var_t mask;

	int i;

	int rc = 0;



	if (!(queue && queue->irq))

		return rc;



	/* cpumask_var_t is either a pointer or array, allocation works here */

	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))

		return -ENOMEM;



	/* while we have extra cpu give one extra to this irq */

	if (*stragglers) {

		stride++;

		(*stragglers)--;

	}

	/* atomic write is safer than writing bit by bit directly */

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

		cpumask_set_cpu(*cpu, mask);

		*cpu = cpumask_next_wrap(*cpu, cpu_online_mask,

					 nr_cpu_ids, false);

	}

	/* set queue affinity mask */

	cpumask_copy(queue->affinity_mask, mask);

	rc = irq_set_affinity_and_hint(queue->irq, queue->affinity_mask);

	free_cpumask_var(mask);



	return rc;

}



/* assumes cpu read lock is held */

static void ibmvnic_set_affinity(struct ibmvnic_adapter *adapter)

{

	struct ibmvnic_sub_crq_queue **rxqs = adapter->rx_scrq;

	struct ibmvnic_sub_crq_queue **txqs = adapter->tx_scrq;

	struct ibmvnic_sub_crq_queue *queue;

	int num_rxqs = adapter->num_active_rx_scrqs;

	int num_txqs = adapter->num_active_tx_scrqs;

	int total_queues, stride, stragglers, i;

	unsigned int num_cpu, cpu;

	int rc = 0;



	netdev_dbg(adapter->netdev, "%s: Setting irq affinity hints", __func__);

	if (!(adapter->rx_scrq && adapter->tx_scrq)) {

		netdev_warn(adapter->netdev,

			    "%s: Set affinity failed, queues not allocated\n",

			    __func__);

		return;

	}



	total_queues = num_rxqs + num_txqs;

	num_cpu = num_online_cpus();

	/* number of cpu's assigned per irq */

	stride = max_t(int, num_cpu / total_queues, 1);

	/* number of leftover cpu's */

	stragglers = num_cpu >= total_queues ? num_cpu % total_queues : 0;

	/* next available cpu to assign irq to */

	cpu = cpumask_next(-1, cpu_online_mask);



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

		queue = txqs[i];

		rc = ibmvnic_set_queue_affinity(queue, &cpu, &stragglers,

						stride);

		if (rc)

			goto out;

	}



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

		queue = rxqs[i];

		rc = ibmvnic_set_queue_affinity(queue, &cpu, &stragglers,

						stride);

		if (rc)

			goto out;

	}



out:

	if (rc) {

		netdev_warn(adapter->netdev,

			    "%s: Set affinity failed, queue addr = %p, IRQ = %d, rc = %d.\n",

			    __func__, queue, queue->irq, rc);

		ibmvnic_clean_affinity(adapter);

	}

}



static long h_reg_sub_crq(unsigned long unit_address, unsigned long token,

			  unsigned long length, unsigned long *number,

			  unsigned long *irq)
@@ -3626,6 +3753,8 @@ static int reset_sub_crq_queues(struct ibmvnic_adapter *adapter) 
	if (!adapter->tx_scrq || !adapter->rx_scrq)

		return -EINVAL;



	ibmvnic_clean_affinity(adapter);



	for (i = 0; i < adapter->req_tx_queues; i++) {

		netdev_dbg(adapter->netdev, "Re-setting tx_scrq[%d]\n", i);

		rc = reset_one_sub_crq_queue(adapter, adapter->tx_scrq[i]);
@@ -3675,6 +3804,7 @@ static void release_sub_crq_queue(struct ibmvnic_adapter *adapter, 
	dma_unmap_single(dev, scrq->msg_token, 4 * PAGE_SIZE,

			 DMA_BIDIRECTIONAL);

	free_pages((unsigned long)scrq->msgs, 2);

	free_cpumask_var(scrq->affinity_mask);

	kfree(scrq);

}
@@ -3695,6 +3825,8 @@ static struct ibmvnic_sub_crq_queue *init_sub_crq_queue(struct ibmvnic_adapter 
		dev_warn(dev, "Couldn't allocate crq queue messages page\n");

		goto zero_page_failed;

	}

	if (!zalloc_cpumask_var(&scrq->affinity_mask, GFP_KERNEL))

		goto cpumask_alloc_failed;



	scrq->msg_token = dma_map_single(dev, scrq->msgs, 4 * PAGE_SIZE,

					 DMA_BIDIRECTIONAL);
@@ -3747,6 +3879,8 @@ static struct ibmvnic_sub_crq_queue *init_sub_crq_queue(struct ibmvnic_adapter 
	dma_unmap_single(dev, scrq->msg_token, 4 * PAGE_SIZE,

			 DMA_BIDIRECTIONAL);

map_failed:

	free_cpumask_var(scrq->affinity_mask);

cpumask_alloc_failed:

	free_pages((unsigned long)scrq->msgs, 2);

zero_page_failed:

	kfree(scrq);
@@ -3758,6 +3892,7 @@ static void release_sub_crqs(struct ibmvnic_adapter *adapter, bool do_h_free) 
{

	int i;



	ibmvnic_clean_affinity(adapter);

	if (adapter->tx_scrq) {

		for (i = 0; i < adapter->num_active_tx_scrqs; i++) {

			if (!adapter->tx_scrq[i])
@@ -4035,6 +4170,11 @@ static int init_sub_crq_irqs(struct ibmvnic_adapter *adapter) 
			goto req_rx_irq_failed;

		}

	}



	cpus_read_lock();

	ibmvnic_set_affinity(adapter);

	cpus_read_unlock();



	return rc;



req_rx_irq_failed:

drivers/net/ethernet/ibm/ibmvnic.h

+1 −0
Original line number Diff line number Diff line
@@ -825,6 +825,7 @@ struct ibmvnic_sub_crq_queue { 
	atomic_t used;

	char name[32];

	u64 handle;

	cpumask_var_t affinity_mask;

} ____cacheline_aligned;



struct ibmvnic_long_term_buff {