Commit 62111654 authored by Dragos Tatulea's avatar Dragos Tatulea Committed by Michael S. Tsirkin
Browse files

vdpa/mlx5: Postpone MR deletion 



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: default avatarDragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: default avatarCosmin Ratiu <cratiu@nvidia.com>
Message-Id: <20240830105838.2666587-9-dtatulea@nvidia.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent f30a1232

drivers/vdpa/mlx5/core/mlx5_vdpa.h

+10 −0
Original line number Diff line number Diff line
@@ -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 {

drivers/vdpa/mlx5/core/mr.c

+52 −3
Original line number Diff line number Diff line
@@ -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,
@@ -851,9 +887,17 @@ 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;

}
@@ -861,5 +905,10 @@ 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);

}

drivers/vdpa/mlx5/net/mlx5_vnet.c

+2 −2
Original line number Diff line number Diff line
@@ -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 int mlx5_vdpa_set_attr(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *dev,