Currently, when a new MR is set up, the old MR is deleted. MR deletion
is about 30-40% the time of MR creation. As deleting the old MR is not
important for the process of setting up the new MR, this operation
can be postponed.
This series adds a workqueue that does MR garbage collection at a later
point. If the MR lock is taken, the handler will back off and
reschedule. The exception during shutdown: then the handler must
not postpone the work.
Note that this is only a speculative optimization: if there is some
mapping operation that is triggered while the garbage collector handler
has the lock taken, this operation it will have to wait for the handler
to finish.
Signed-off-by: Dragos Tatulea <dtatu...@nvidia.com>
Reviewed-by: Cosmin Ratiu <cra...@nvidia.com>
---
drivers/vdpa/mlx5/core/mlx5_vdpa.h | 10 ++++++
drivers/vdpa/mlx5/core/mr.c | 55 ++++++++++++++++++++++++++++--
drivers/vdpa/mlx5/net/mlx5_vnet.c | 4 +--
3 files changed, 64 insertions(+), 5 deletions(-)
diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
index c3e17bc888e8..2cedf7e2dbc4 100644
--- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
+++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
@@ -86,8 +86,18 @@ enum {
struct mlx5_vdpa_mr_resources {
struct mlx5_vdpa_mr *mr[MLX5_VDPA_NUM_AS];
unsigned int group2asid[MLX5_VDPA_NUMVQ_GROUPS];
+
+ /* Pre-deletion mr list */
struct list_head mr_list_head;
+
+ /* Deferred mr list */
+ struct list_head mr_gc_list_head;
+ struct workqueue_struct *wq_gc;
+ struct delayed_work gc_dwork_ent;
+
struct mutex lock;
+
+ atomic_t shutdown;
};
struct mlx5_vdpa_dev {
diff --git a/drivers/vdpa/mlx5/core/mr.c b/drivers/vdpa/mlx5/core/mr.c
index 0bc99f159046..55755e97a946 100644
--- a/drivers/vdpa/mlx5/core/mr.c
+++ b/drivers/vdpa/mlx5/core/mr.c
@@ -653,14 +653,50 @@ static void _mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev
*mvdev, struct mlx5_vdpa_
kfree(mr);
}
+/* There can be multiple .set_map() operations in quick succession.
+ * This large delay is a simple way to prevent the MR cleanup from blocking
+ * .set_map() MR creation in this scenario.
+ */
+#define MLX5_VDPA_MR_GC_TRIGGER_MS 2000
+
+static void mlx5_vdpa_mr_gc_handler(struct work_struct *work)
+{
+ struct mlx5_vdpa_mr_resources *mres;
+ struct mlx5_vdpa_mr *mr, *tmp;
+ struct mlx5_vdpa_dev *mvdev;
+
+ mres = container_of(work, struct mlx5_vdpa_mr_resources,
gc_dwork_ent.work);
+
+ if (atomic_read(&mres->shutdown)) {
+ mutex_lock(&mres->lock);
+ } else if (!mutex_trylock(&mres->lock)) {
+ queue_delayed_work(mres->wq_gc, &mres->gc_dwork_ent,
+
msecs_to_jiffies(MLX5_VDPA_MR_GC_TRIGGER_MS));
+ return;
+ }
+
+ mvdev = container_of(mres, struct mlx5_vdpa_dev, mres);
+
+ list_for_each_entry_safe(mr, tmp, &mres->mr_gc_list_head, mr_list) {
+ _mlx5_vdpa_destroy_mr(mvdev, mr);
+ }
+
+ mutex_unlock(&mres->lock);
+}
+
static void _mlx5_vdpa_put_mr(struct mlx5_vdpa_dev *mvdev,
struct mlx5_vdpa_mr *mr)
{
+ struct mlx5_vdpa_mr_resources *mres = &mvdev->mres;
+
if (!mr)
return;
- if (refcount_dec_and_test(&mr->refcount))
- _mlx5_vdpa_destroy_mr(mvdev, mr);
+ if (refcount_dec_and_test(&mr->refcount)) {
+ list_move_tail(&mr->mr_list, &mres->mr_gc_list_head);
+ queue_delayed_work(mres->wq_gc, &mres->gc_dwork_ent,
+
msecs_to_jiffies(MLX5_VDPA_MR_GC_TRIGGER_MS));
+ }
}
void mlx5_vdpa_put_mr(struct mlx5_vdpa_dev *mvdev,
@@ -848,9 +884,17 @@ int mlx5_vdpa_init_mr_resources(struct mlx5_vdpa_dev
*mvdev)
{
struct mlx5_vdpa_mr_resources *mres = &mvdev->mres;
- INIT_LIST_HEAD(&mres->mr_list_head);
+ mres->wq_gc = create_singlethread_workqueue("mlx5_vdpa_mr_gc");
+ if (!mres->wq_gc)
+ return -ENOMEM;
+
+ INIT_DELAYED_WORK(&mres->gc_dwork_ent, mlx5_vdpa_mr_gc_handler);
+
mutex_init(&mres->lock);
+ INIT_LIST_HEAD(&mres->mr_list_head);
+ INIT_LIST_HEAD(&mres->mr_gc_list_head);
+
return 0;
}
@@ -858,5 +902,10 @@ void mlx5_vdpa_destroy_mr_resources(struct mlx5_vdpa_dev
*mvdev)
{
struct mlx5_vdpa_mr_resources *mres = &mvdev->mres;
+ atomic_set(&mres->shutdown, 1);
+
+ flush_delayed_work(&mres->gc_dwork_ent);
+ destroy_workqueue(mres->wq_gc);
+ mres->wq_gc = NULL;
mutex_destroy(&mres->lock);
}
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index fc86e33e620a..9ccbe1c1ec15 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -3435,6 +3435,8 @@ static void mlx5_vdpa_free(struct vdpa_device *vdev)
free_fixed_resources(ndev);
mlx5_vdpa_clean_mrs(mvdev);
mlx5_vdpa_destroy_mr_resources(&ndev->mvdev);
+ mlx5_cmd_cleanup_async_ctx(&mvdev->async_ctx);
+
if (!is_zero_ether_addr(ndev->config.mac)) {
pfmdev = pci_get_drvdata(pci_physfn(mvdev->mdev->pdev));
mlx5_mpfs_del_mac(pfmdev, ndev->config.mac);
@@ -4042,8 +4044,6 @@ static void mlx5_vdpa_dev_del(struct vdpa_mgmt_dev
*v_mdev, struct vdpa_device *
mvdev->wq = NULL;
destroy_workqueue(wq);
mgtdev->ndev = NULL;
-
- mlx5_cmd_cleanup_async_ctx(&mvdev->async_ctx);
}
static const struct vdpa_mgmtdev_ops mdev_ops = {
--
2.45.1
