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

Cindy Lu
2025-04-03T05:53:09Z

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
> >
>