[v3] vhost: Add support of kthread API

[PATCH v3 1/9] vhost: Add a new parameter to allow user select kthread

Posted by Cindy Lu 2 weeks, 5 days ago

The vhost now uses vhost_task and workers as a child of the owner thread.
While this aligns with containerization principles,it confuses some legacy
userspace app, Therefore, we are reintroducing kthread API support.

Introduce a new parameter to enable users to choose between
kthread and task mode. This will be exposed by module_param() later.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 drivers/vhost/vhost.c | 2 ++
 drivers/vhost/vhost.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9ac25d08f473..eff6acbbb63b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -41,6 +41,7 @@ static int max_iotlb_entries = 2048;
 module_param(max_iotlb_entries, int, 0444);
 MODULE_PARM_DESC(max_iotlb_entries,
 	"Maximum number of iotlb entries. (default: 2048)");
+static bool inherit_owner_default = true;
 
 enum {
 	VHOST_MEMORY_F_LOG = 0x1,
@@ -552,6 +553,7 @@ void vhost_dev_init(struct vhost_dev *dev,
 	dev->byte_weight = byte_weight;
 	dev->use_worker = use_worker;
 	dev->msg_handler = msg_handler;
+	dev->inherit_owner = inherit_owner_default;
 	init_waitqueue_head(&dev->wait);
 	INIT_LIST_HEAD(&dev->read_list);
 	INIT_LIST_HEAD(&dev->pending_list);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bb75a292d50c..c650c4506c70 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -176,6 +176,7 @@ struct vhost_dev {
 	int byte_weight;
 	struct xarray worker_xa;
 	bool use_worker;
+	bool inherit_owner;
 	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 			   struct vhost_iotlb_msg *msg);
 };
-- 
2.45.0

Re: [PATCH v3 1/9] vhost: Add a new parameter to allow user select kthread

Posted by Jason Wang 2 weeks, 5 days ago

On Tue, Nov 5, 2024 at 3:27 PM Cindy Lu <lulu@redhat.com> wrote:
>
> The vhost now uses vhost_task and workers as a child of the owner thread.
> While this aligns with containerization principles,it confuses some legacy
> userspace app, Therefore, we are reintroducing kthread API support.
>
> Introduce a new parameter to enable users to choose between
> kthread and task mode. This will be exposed by module_param() later.
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  drivers/vhost/vhost.c | 2 ++
>  drivers/vhost/vhost.h | 1 +
>  2 files changed, 3 insertions(+)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 9ac25d08f473..eff6acbbb63b 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -41,6 +41,7 @@ static int max_iotlb_entries = 2048;
>  module_param(max_iotlb_entries, int, 0444);
>  MODULE_PARM_DESC(max_iotlb_entries,
>         "Maximum number of iotlb entries. (default: 2048)");
> +static bool inherit_owner_default = true;

I wonder how management can make a decision for this value.

Thanks