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Commit 2ca653d6 authored by Caleb Raitto's avatar Caleb Raitto Committed by David S. Miller
Browse files

virtio_net: Stripe queue affinities across cores. 



Always set the affinity hint, even if #cpu != #vq.

Handle the case where #cpu > #vq (including when #cpu % #vq != 0) and
when #vq > #cpu (including when #vq % #cpu != 0).

Signed-off-by: default avatarCaleb Raitto <caraitto@google.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Acked-by: default avatarJon Olson <jonolson@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 19e226e8

drivers/net/virtio_net.c

+27 −15
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/average.h>

#include <linux/filter.h>

#include <linux/netdevice.h>

#include <linux/kernel.h>

#include <linux/pci.h>

#include <net/route.h>

#include <net/xdp.h>
@@ -1888,30 +1889,41 @@ static void virtnet_clean_affinity(struct virtnet_info *vi, long hcpu) 


static void virtnet_set_affinity(struct virtnet_info *vi)

{

	int i;

	int cpu;

	cpumask_var_t mask;

	int stragglers;

	int group_size;

	int i, j, cpu;

	int num_cpu;

	int stride;



	/* In multiqueue mode, when the number of cpu is equal to the number of

	 * queue pairs, we let the queue pairs to be private to one cpu by

	 * setting the affinity hint to eliminate the contention.

	 */

	if (vi->curr_queue_pairs == 1 ||

	    vi->max_queue_pairs != num_online_cpus()) {

	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {

		virtnet_clean_affinity(vi, -1);

		return;

	}



	i = 0;

	for_each_online_cpu(cpu) {

		const unsigned long *mask = cpumask_bits(cpumask_of(cpu));

	num_cpu = num_online_cpus();

	stride = max_t(int, num_cpu / vi->curr_queue_pairs, 1);

	stragglers = num_cpu >= vi->curr_queue_pairs ?

			num_cpu % vi->curr_queue_pairs :

			0;

	cpu = cpumask_next(-1, cpu_online_mask);



		virtqueue_set_affinity(vi->rq[i].vq, cpumask_of(cpu));

		virtqueue_set_affinity(vi->sq[i].vq, cpumask_of(cpu));

		__netif_set_xps_queue(vi->dev, mask, i, false);

		i++;

	for (i = 0; i < vi->curr_queue_pairs; i++) {

		group_size = stride + (i < stragglers ? 1 : 0);



		for (j = 0; j < group_size; j++) {

			cpumask_set_cpu(cpu, mask);

			cpu = cpumask_next_wrap(cpu, cpu_online_mask,

						nr_cpu_ids, false);

		}

		virtqueue_set_affinity(vi->rq[i].vq, mask);

		virtqueue_set_affinity(vi->sq[i].vq, mask);

		__netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, false);

		cpumask_clear(mask);

	}



	vi->affinity_hint_set = true;

	free_cpumask_var(mask);

}



static int virtnet_cpu_online(unsigned int cpu, struct hlist_node *node)