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virtio_scsi: use virtio IRQ affinity
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Use automatic IRQ affinity assignment in the virtio layer if available,
and build the blk-mq queues based on it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@mstsirkin
Christoph Hellwig authored and mstsirkin committed Feb 27, 2017
1 parent ad71473 commit 0d9f0a5
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Showing 2 changed files with 12 additions and 115 deletions.
126 changes: 12 additions & 114 deletions drivers/scsi/virtio_scsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mempool.h>
#include <linux/interrupt.h>
#include <linux/virtio.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
Expand All @@ -29,6 +30,7 @@
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_tcq.h>
#include <linux/seqlock.h>
#include <linux/blk-mq-virtio.h>

#define VIRTIO_SCSI_MEMPOOL_SZ 64
#define VIRTIO_SCSI_EVENT_LEN 8
Expand Down Expand Up @@ -108,7 +110,6 @@ struct virtio_scsi {
bool affinity_hint_set;

struct hlist_node node;
struct hlist_node node_dead;

/* Protected by event_vq lock */
bool stop_events;
Expand All @@ -118,7 +119,6 @@ struct virtio_scsi {
struct virtio_scsi_vq req_vqs[];
};

static enum cpuhp_state virtioscsi_online;
static struct kmem_cache *virtscsi_cmd_cache;
static mempool_t *virtscsi_cmd_pool;

Expand Down Expand Up @@ -766,6 +766,13 @@ static void virtscsi_target_destroy(struct scsi_target *starget)
kfree(tgt);
}

static int virtscsi_map_queues(struct Scsi_Host *shost)
{
struct virtio_scsi *vscsi = shost_priv(shost);

return blk_mq_virtio_map_queues(&shost->tag_set, vscsi->vdev, 2);
}

static struct scsi_host_template virtscsi_host_template_single = {
.module = THIS_MODULE,
.name = "Virtio SCSI HBA",
Expand Down Expand Up @@ -801,6 +808,7 @@ static struct scsi_host_template virtscsi_host_template_multi = {
.use_clustering = ENABLE_CLUSTERING,
.target_alloc = virtscsi_target_alloc,
.target_destroy = virtscsi_target_destroy,
.map_queues = virtscsi_map_queues,
.track_queue_depth = 1,
};

Expand All @@ -817,80 +825,6 @@ static struct scsi_host_template virtscsi_host_template_multi = {
virtio_cwrite(vdev, struct virtio_scsi_config, fld, &__val); \
} while(0)

static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
{
int i;
int cpu;

/* In multiqueue mode, when the number of cpu is equal
* to the number of request queues, we let the qeueues
* to be private to one cpu by setting the affinity hint
* to eliminate the contention.
*/
if ((vscsi->num_queues == 1 ||
vscsi->num_queues != num_online_cpus()) && affinity) {
if (vscsi->affinity_hint_set)
affinity = false;
else
return;
}

if (affinity) {
i = 0;
for_each_online_cpu(cpu) {
virtqueue_set_affinity(vscsi->req_vqs[i].vq, cpu);
i++;
}

vscsi->affinity_hint_set = true;
} else {
for (i = 0; i < vscsi->num_queues; i++) {
if (!vscsi->req_vqs[i].vq)
continue;

virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
}

vscsi->affinity_hint_set = false;
}
}

static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
{
get_online_cpus();
__virtscsi_set_affinity(vscsi, affinity);
put_online_cpus();
}

static int virtscsi_cpu_online(unsigned int cpu, struct hlist_node *node)
{
struct virtio_scsi *vscsi = hlist_entry_safe(node, struct virtio_scsi,
node);
__virtscsi_set_affinity(vscsi, true);
return 0;
}

static int virtscsi_cpu_notif_add(struct virtio_scsi *vi)
{
int ret;

ret = cpuhp_state_add_instance(virtioscsi_online, &vi->node);
if (ret)
return ret;

ret = cpuhp_state_add_instance(CPUHP_VIRT_SCSI_DEAD, &vi->node_dead);
if (ret)
cpuhp_state_remove_instance(virtioscsi_online, &vi->node);
return ret;
}

static void virtscsi_cpu_notif_remove(struct virtio_scsi *vi)
{
cpuhp_state_remove_instance_nocalls(virtioscsi_online, &vi->node);
cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_SCSI_DEAD,
&vi->node_dead);
}

static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
struct virtqueue *vq)
{
Expand All @@ -900,14 +834,8 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,

static void virtscsi_remove_vqs(struct virtio_device *vdev)
{
struct Scsi_Host *sh = virtio_scsi_host(vdev);
struct virtio_scsi *vscsi = shost_priv(sh);

virtscsi_set_affinity(vscsi, false);

/* Stop all the virtqueues. */
vdev->config->reset(vdev);

vdev->config->del_vqs(vdev);
}

Expand All @@ -920,6 +848,7 @@ static int virtscsi_init(struct virtio_device *vdev,
vq_callback_t **callbacks;
const char **names;
struct virtqueue **vqs;
struct irq_affinity desc = { .pre_vectors = 2 };

num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE;
vqs = kmalloc(num_vqs * sizeof(struct virtqueue *), GFP_KERNEL);
Expand All @@ -942,7 +871,7 @@ static int virtscsi_init(struct virtio_device *vdev,

/* Discover virtqueues and write information to configuration. */
err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names,
NULL);
&desc);
if (err)
goto out;

Expand Down Expand Up @@ -1008,10 +937,6 @@ static int virtscsi_probe(struct virtio_device *vdev)
if (err)
goto virtscsi_init_failed;

err = virtscsi_cpu_notif_add(vscsi);
if (err)
goto scsi_add_host_failed;

cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
Expand Down Expand Up @@ -1066,20 +991,13 @@ static void virtscsi_remove(struct virtio_device *vdev)
virtscsi_cancel_event_work(vscsi);

scsi_remove_host(shost);

virtscsi_cpu_notif_remove(vscsi);

virtscsi_remove_vqs(vdev);
scsi_host_put(shost);
}

#ifdef CONFIG_PM_SLEEP
static int virtscsi_freeze(struct virtio_device *vdev)
{
struct Scsi_Host *sh = virtio_scsi_host(vdev);
struct virtio_scsi *vscsi = shost_priv(sh);

virtscsi_cpu_notif_remove(vscsi);
virtscsi_remove_vqs(vdev);
return 0;
}
Expand All @@ -1094,11 +1012,6 @@ static int virtscsi_restore(struct virtio_device *vdev)
if (err)
return err;

err = virtscsi_cpu_notif_add(vscsi);
if (err) {
vdev->config->del_vqs(vdev);
return err;
}
virtio_device_ready(vdev);

if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
Expand Down Expand Up @@ -1153,16 +1066,6 @@ static int __init init(void)
pr_err("mempool_create() for virtscsi_cmd_pool failed\n");
goto error;
}
ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
"scsi/virtio:online",
virtscsi_cpu_online, NULL);
if (ret < 0)
goto error;
virtioscsi_online = ret;
ret = cpuhp_setup_state_multi(CPUHP_VIRT_SCSI_DEAD, "scsi/virtio:dead",
NULL, virtscsi_cpu_online);
if (ret)
goto error;
ret = register_virtio_driver(&virtio_scsi_driver);
if (ret < 0)
goto error;
Expand All @@ -1178,17 +1081,12 @@ static int __init init(void)
kmem_cache_destroy(virtscsi_cmd_cache);
virtscsi_cmd_cache = NULL;
}
if (virtioscsi_online)
cpuhp_remove_multi_state(virtioscsi_online);
cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
return ret;
}

static void __exit fini(void)
{
unregister_virtio_driver(&virtio_scsi_driver);
cpuhp_remove_multi_state(virtioscsi_online);
cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
mempool_destroy(virtscsi_cmd_pool);
kmem_cache_destroy(virtscsi_cmd_cache);
}
Expand Down
1 change: 0 additions & 1 deletion include/linux/cpuhotplug.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@ enum cpuhp_state {
CPUHP_ARM_OMAP_WAKE_DEAD,
CPUHP_IRQ_POLL_DEAD,
CPUHP_BLOCK_SOFTIRQ_DEAD,
CPUHP_VIRT_SCSI_DEAD,
CPUHP_ACPI_CPUDRV_DEAD,
CPUHP_S390_PFAULT_DEAD,
CPUHP_BLK_MQ_DEAD,
Expand Down

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