[PATCH v8 1/8] vhost: Add a new parameter in vhost_dev to allow user select kthread

Cindy Lu posted 8 patches 8 months, 3 weeks ago
There is a newer version of this series
[PATCH v8 1/8] vhost: Add a new parameter in vhost_dev to allow user select kthread
Posted by Cindy Lu 8 months, 3 weeks 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.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 drivers/vhost/vhost.c | 1 +
 drivers/vhost/vhost.h | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 63612faeab72..250dc43f1786 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -552,6 +552,7 @@ 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 = true;
 	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..19bb94922a0e 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -176,6 +176,15 @@ struct vhost_dev {
 	int byte_weight;
 	struct xarray worker_xa;
 	bool use_worker;
+	/*
+	 * If inherit_owner is true we use vhost_tasks to create
+	 * the worker so all settings/limits like cgroups, NPROC,
+	 * scheduler, etc are inherited from the owner. If false,
+	 * we use kthreads and only attach to the same cgroups
+	 * as the owner for compat with older kernels.
+	 * here we use true as default value
+	 */
+	bool inherit_owner;
 	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 			   struct vhost_iotlb_msg *msg);
 };
-- 
2.45.0
Re: [PATCH v8 1/8] vhost: Add a new parameter in vhost_dev to allow user select kthread
Posted by Stefano Garzarella 8 months, 3 weeks ago
On Fri, Mar 28, 2025 at 06:02:45PM +0800, Cindy Lu 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

nit: missing space "principles,it"

>userspace app, Therefore, we are reintroducing kthread API support.

nit: "userspace app, Therefore" -> "userspace app. Therefore"

>
>Introduce a new parameter to enable users to choose between
>kthread and task mode.

I would explain that by default this is true, and so we are not changing 
the behavior with this patch.

>
>Signed-off-by: Cindy Lu <lulu@redhat.com>
>---
> drivers/vhost/vhost.c | 1 +
> drivers/vhost/vhost.h | 9 +++++++++
> 2 files changed, 10 insertions(+)

Anyway, the patch LGTM with or without the commit tweaks:

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>index 63612faeab72..250dc43f1786 100644
>--- a/drivers/vhost/vhost.c
>+++ b/drivers/vhost/vhost.c
>@@ -552,6 +552,7 @@ 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 = true;
> 	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..19bb94922a0e 100644
>--- a/drivers/vhost/vhost.h
>+++ b/drivers/vhost/vhost.h
>@@ -176,6 +176,15 @@ struct vhost_dev {
> 	int byte_weight;
> 	struct xarray worker_xa;
> 	bool use_worker;
>+	/*
>+	 * If inherit_owner is true we use vhost_tasks to create
>+	 * the worker so all settings/limits like cgroups, NPROC,
>+	 * scheduler, etc are inherited from the owner. If false,
>+	 * we use kthreads and only attach to the same cgroups
>+	 * as the owner for compat with older kernels.
>+	 * here we use true as default value
>+	 */
>+	bool inherit_owner;
> 	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
> 			   struct vhost_iotlb_msg *msg);
> };
>-- 
>2.45.0
>
Re: [PATCH v8 1/8] vhost: Add a new parameter in vhost_dev to allow user select kthread
Posted by Cindy Lu 8 months, 2 weeks ago
On Tue, Apr 1, 2025 at 9:30 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> On Fri, Mar 28, 2025 at 06:02:45PM +0800, Cindy Lu 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
>
> nit: missing space "principles,it"
>
> >userspace app, Therefore, we are reintroducing kthread API support.
>
> nit: "userspace app, Therefore" -> "userspace app. Therefore"
>
> >
> >Introduce a new parameter to enable users to choose between
> >kthread and task mode.
>
> I would explain that by default this is true, and so we are not changing
> the behavior with this patch.
>
Sure,I will change these
Thanks
Cindy
> >
> >Signed-off-by: Cindy Lu <lulu@redhat.com>
> >---
> > drivers/vhost/vhost.c | 1 +
> > drivers/vhost/vhost.h | 9 +++++++++
> > 2 files changed, 10 insertions(+)
>
> Anyway, the patch LGTM with or without the commit tweaks:
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
>
> >
> >diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> >index 63612faeab72..250dc43f1786 100644
> >--- a/drivers/vhost/vhost.c
> >+++ b/drivers/vhost/vhost.c
> >@@ -552,6 +552,7 @@ 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 = true;
> >       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..19bb94922a0e 100644
> >--- a/drivers/vhost/vhost.h
> >+++ b/drivers/vhost/vhost.h
> >@@ -176,6 +176,15 @@ struct vhost_dev {
> >       int byte_weight;
> >       struct xarray worker_xa;
> >       bool use_worker;
> >+      /*
> >+       * If inherit_owner is true we use vhost_tasks to create
> >+       * the worker so all settings/limits like cgroups, NPROC,
> >+       * scheduler, etc are inherited from the owner. If false,
> >+       * we use kthreads and only attach to the same cgroups
> >+       * as the owner for compat with older kernels.
> >+       * here we use true as default value
> >+       */
> >+      bool inherit_owner;
> >       int (*msg_handler)(struct vhost_dev *dev, u32 asid,
> >                          struct vhost_iotlb_msg *msg);
> > };
> >--
> >2.45.0
> >
>