[Virtio-fs] [PATCH] virtiofs: Enable multiple request queues

[Connor Kuehl]

Distribute requests across the multiqueue complex automatically based
on the IRQ affinity.

Suggested-by: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Connor Kuehl <cku...@redhat.com>
---
 fs/fuse/virtio_fs.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index bcb8a02e2d8b..dcdc8b7b1ad5 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -30,6 +30,10 @@
 static DEFINE_MUTEX(virtio_fs_mutex);
 static LIST_HEAD(virtio_fs_instances);
 
+struct virtio_fs_vq;
+
+DEFINE_PER_CPU(struct virtio_fs_vq *, this_cpu_fsvq);
+
 enum {
        VQ_HIPRIO,
        VQ_REQUEST
@@ -673,6 +677,7 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
        struct virtqueue **vqs;
        vq_callback_t **callbacks;
        const char **names;
+       struct irq_affinity desc = { .pre_vectors = 1, .nr_sets = 1, };
        unsigned int i;
        int ret = 0;
 
@@ -681,6 +686,9 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
        if (fs->num_request_queues == 0)
                return -EINVAL;
 
+       fs->num_request_queues = min_t(unsigned int, nr_cpu_ids,
+                                      fs->num_request_queues);
+
        fs->nvqs = VQ_REQUEST + fs->num_request_queues;
        fs->vqs = kcalloc(fs->nvqs, sizeof(fs->vqs[VQ_HIPRIO]), GFP_KERNEL);
        if (!fs->vqs)
@@ -710,12 +718,24 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
                names[i] = fs->vqs[i].name;
        }
 
-       ret = virtio_find_vqs(vdev, fs->nvqs, vqs, callbacks, names, NULL);
+       ret = virtio_find_vqs(vdev, fs->nvqs, vqs, callbacks, names, &desc);
        if (ret < 0)
                goto out;
 
-       for (i = 0; i < fs->nvqs; i++)
+       for (i = 0; i < fs->nvqs; i++) {
+               const struct cpumask *mask;
+               unsigned int cpu;
+
                fs->vqs[i].vq = vqs[i];
+               if (i == VQ_HIPRIO)
+                       continue;
+
+               mask = vdev->config->get_vq_affinity(vdev, i);
+               for_each_cpu(cpu, mask) {
+                       struct virtio_fs_vq **cpu_vq = 
per_cpu_ptr(&this_cpu_fsvq, cpu);
+                       *cpu_vq = &fs->vqs[i];
+               }
+       }
 
        virtio_fs_start_all_queues(fs);
 out:
@@ -877,8 +897,6 @@ static int virtio_fs_probe(struct virtio_device *vdev)
        if (ret < 0)
                goto out;
 
-       /* TODO vq affinity */
-
        ret = virtio_fs_setup_dax(vdev, fs);
        if (ret < 0)
                goto out_vqs;
@@ -1225,7 +1243,6 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq 
*fsvq,
 static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
 __releases(fiq->lock)
 {
-       unsigned int queue_id = VQ_REQUEST; /* TODO multiqueue */
        struct virtio_fs *fs;
        struct fuse_req *req;
        struct virtio_fs_vq *fsvq;
@@ -1245,7 +1262,8 @@ __releases(fiq->lock)
                 req->in.h.nodeid, req->in.h.len,
                 fuse_len_args(req->args->out_numargs, req->args->out_args));
 
-       fsvq = &fs->vqs[queue_id];
+       fsvq = this_cpu_read(this_cpu_fsvq);
+
        ret = virtio_fs_enqueue_req(fsvq, req, false);
        if (ret < 0) {
                if (ret == -ENOMEM || ret == -ENOSPC) {
-- 
2.30.2

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