[PATCH 9/9] virtio_scsi: use virtio IRQ affinity

Christoph Hellwig
2017-02-05T17:16:03Z

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>
---
drivers/scsi/virtio_scsi.c | 126 +++++----------------------------------------
include/linux/cpuhotplug.h | 1 -
2 files changed, 12 insertions(+), 115 deletions(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 32a16293436b..5582c8baeabb 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -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>
@@ -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
@@ -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;
@@ -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;

@@ -757,6 +757,13 @@ 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",
@@ -792,6 +799,7 @@ 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,
};

@@ -808,80 +816,6 @@ 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)
{
@@ -891,14 +825,8 @@ 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);
}

@@ -911,6 +839,7 @@ 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);
@@ -933,7 +862,7 @@ 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;

@@ -999,10 +928,6 @@ 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;
@@ -1057,9 +982,6 @@ 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);
}
@@ -1067,10 +989,6 @@ static void virtscsi_remove(struct virtio_device *vdev)
#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;
}
@@ -1085,11 +1003,6 @@ 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))
@@ -1144,16 +1057,6 @@ 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;
@@ -1169,17 +1072,12 @@ 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);
}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 921acaaa1601..01aea80a503e 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -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,
--
2.11.0