[PATCH] virtiofs: Enable multiple request queues

From: Connor Kuehl
Date: Fri May 07 2021 - 18:15:39 EST


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

Suggested-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Signed-off-by: Connor Kuehl <ckuehl@xxxxxxxxxx>
---
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