In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),   
the vhost now uses vhost_task and operates as a child of the   
owner thread. This aligns with containerization principles.   
However, this change has caused confusion for some legacy   
userspace applications. Therefore, we are reintroducing   
support for the kthread API.  

In this series, a new UAPI is implemented to allow   
userspace applications to configure their thread mode. 

Changelog v2:
 1. Change the module_param's name to enforce_inherit_owner, and the default value is true.
 2. Change the UAPI's name to VHOST_SET_INHERIT_FROM_OWNER.
 
Changelog v3:
 1. Change the module_param's name to inherit_owner_default, and the default value is true.
 2. Add a structure for task function; the worker will select a different mode based on the value inherit_owner.
 3. device will have their own inherit_owner in struct vhost_dev
 4. Address other comments

Changelog v4: 
 1. remove the module_param, only keep the UAPI
 2. remove the structure for task function; change to use the function pointer in vhost_worker
 3. fix the issue in vhost_worker_create and vhost_dev_ioctl
 4. Address other comments

Changelog v5: 
 1. Change wakeup and stop function pointers in struct vhost_worker to void.
 2. merging patches 4, 5, 6 in a single patch
 3. Fix spelling issues and address other comments.
 
Tested with QEMU with kthread mode/task mode/kthread+task mode

Cindy Lu (6):
  vhost: Add a new parameter in vhost_dev to allow user select kthread
  vhost: Add the vhost_worker to support kthread
  vhost: Add the cgroup related function
  vhost: Add worker related functions to support kthread
  vhost: Add new UAPI to support change to task mode
  vhost_scsi: Add check for inherit_owner status

 drivers/vhost/scsi.c       |   8 ++
 drivers/vhost/vhost.c      | 178 +++++++++++++++++++++++++++++++++----
 drivers/vhost/vhost.h      |   4 +
 include/uapi/linux/vhost.h |  19 ++++
 4 files changed, 192 insertions(+), 17 deletions(-)

-- 
2.45.0

On 12/30/24 6:43 AM, Cindy Lu wrote:
> In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),   
> the vhost now uses vhost_task and operates as a child of the   
> owner thread. This aligns with containerization principles.   
> However, this change has caused confusion for some legacy   
> userspace applications. Therefore, we are reintroducing   
> support for the kthread API.  
> 
> In this series, a new UAPI is implemented to allow   
> userspace applications to configure their thread mode. 
> 
Tested the patches with a hacked up QEMU that can toggle the
inherit owner bit so I could test both modes.

Tested-by: Mike Christie <michael.christie@oracle.com>

On Mon, Dec 30, 2024 at 08:43:47PM +0800, Cindy Lu wrote:
> In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),   
> the vhost now uses vhost_task and operates as a child of the   
> owner thread. This aligns with containerization principles.   
> However, this change has caused confusion for some legacy   
> userspace applications. Therefore, we are reintroducing   
> support for the kthread API.  


I briefly applied this, but there seem to be a bit too
many nits. So I will wait for v6 with everything addressed.

Thanks!

> In this series, a new UAPI is implemented to allow   
> userspace applications to configure their thread mode. 
> 
> Changelog v2:
>  1. Change the module_param's name to enforce_inherit_owner, and the default value is true.
>  2. Change the UAPI's name to VHOST_SET_INHERIT_FROM_OWNER.
>  
> Changelog v3:
>  1. Change the module_param's name to inherit_owner_default, and the default value is true.
>  2. Add a structure for task function; the worker will select a different mode based on the value inherit_owner.
>  3. device will have their own inherit_owner in struct vhost_dev
>  4. Address other comments
> 
> Changelog v4: 
>  1. remove the module_param, only keep the UAPI
>  2. remove the structure for task function; change to use the function pointer in vhost_worker
>  3. fix the issue in vhost_worker_create and vhost_dev_ioctl
>  4. Address other comments
> 
> Changelog v5: 
>  1. Change wakeup and stop function pointers in struct vhost_worker to void.
>  2. merging patches 4, 5, 6 in a single patch
>  3. Fix spelling issues and address other comments.
>  
> Tested with QEMU with kthread mode/task mode/kthread+task mode
> 
> Cindy Lu (6):
>   vhost: Add a new parameter in vhost_dev to allow user select kthread
>   vhost: Add the vhost_worker to support kthread
>   vhost: Add the cgroup related function
>   vhost: Add worker related functions to support kthread
>   vhost: Add new UAPI to support change to task mode
>   vhost_scsi: Add check for inherit_owner status
> 
>  drivers/vhost/scsi.c       |   8 ++
>  drivers/vhost/vhost.c      | 178 +++++++++++++++++++++++++++++++++----
>  drivers/vhost/vhost.h      |   4 +
>  include/uapi/linux/vhost.h |  19 ++++
>  4 files changed, 192 insertions(+), 17 deletions(-)
> 
> -- 
> 2.45.0

On Wed, Jan 8, 2025 at 8:23 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Dec 30, 2024 at 08:43:47PM +0800, Cindy Lu wrote:
> > In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),
> > the vhost now uses vhost_task and operates as a child of the
> > owner thread. This aligns with containerization principles.
> > However, this change has caused confusion for some legacy
> > userspace applications. Therefore, we are reintroducing
> > support for the kthread API.
>
>
> I briefly applied this, but there seem to be a bit too
> many nits. So I will wait for v6 with everything addressed.
>
> Thanks!
>
sure, I will rebase this to the latest kernel, Thanks
Thanks
Cindy
> > In this series, a new UAPI is implemented to allow
> > userspace applications to configure their thread mode.
> >
> > Changelog v2:
> >  1. Change the module_param's name to enforce_inherit_owner, and the default value is true.
> >  2. Change the UAPI's name to VHOST_SET_INHERIT_FROM_OWNER.
> >
> > Changelog v3:
> >  1. Change the module_param's name to inherit_owner_default, and the default value is true.
> >  2. Add a structure for task function; the worker will select a different mode based on the value inherit_owner.
> >  3. device will have their own inherit_owner in struct vhost_dev
> >  4. Address other comments
> >
> > Changelog v4:
> >  1. remove the module_param, only keep the UAPI
> >  2. remove the structure for task function; change to use the function pointer in vhost_worker
> >  3. fix the issue in vhost_worker_create and vhost_dev_ioctl
> >  4. Address other comments
> >
> > Changelog v5:
> >  1. Change wakeup and stop function pointers in struct vhost_worker to void.
> >  2. merging patches 4, 5, 6 in a single patch
> >  3. Fix spelling issues and address other comments.
> >
> > Tested with QEMU with kthread mode/task mode/kthread+task mode
> >
> > Cindy Lu (6):
> >   vhost: Add a new parameter in vhost_dev to allow user select kthread
> >   vhost: Add the vhost_worker to support kthread
> >   vhost: Add the cgroup related function
> >   vhost: Add worker related functions to support kthread
> >   vhost: Add new UAPI to support change to task mode
> >   vhost_scsi: Add check for inherit_owner status
> >
> >  drivers/vhost/scsi.c       |   8 ++
> >  drivers/vhost/vhost.c      | 178 +++++++++++++++++++++++++++++++++----
> >  drivers/vhost/vhost.h      |   4 +
> >  include/uapi/linux/vhost.h |  19 ++++
> >  4 files changed, 192 insertions(+), 17 deletions(-)
> >
> > --
> > 2.45.0
>

I tested this series v5 with virtio-net regression tests, everything works fine.

Tested-by: Lei Yang <leiyang@redhat.com>


On Mon, Dec 30, 2024 at 8:46 PM Cindy Lu <lulu@redhat.com> wrote:
>
> In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),
> the vhost now uses vhost_task and operates as a child of the
> owner thread. This aligns with containerization principles.
> However, this change has caused confusion for some legacy
> userspace applications. Therefore, we are reintroducing
> support for the kthread API.
>
> In this series, a new UAPI is implemented to allow
> userspace applications to configure their thread mode.
>
> Changelog v2:
>  1. Change the module_param's name to enforce_inherit_owner, and the default value is true.
>  2. Change the UAPI's name to VHOST_SET_INHERIT_FROM_OWNER.
>
> Changelog v3:
>  1. Change the module_param's name to inherit_owner_default, and the default value is true.
>  2. Add a structure for task function; the worker will select a different mode based on the value inherit_owner.
>  3. device will have their own inherit_owner in struct vhost_dev
>  4. Address other comments
>
> Changelog v4:
>  1. remove the module_param, only keep the UAPI
>  2. remove the structure for task function; change to use the function pointer in vhost_worker
>  3. fix the issue in vhost_worker_create and vhost_dev_ioctl
>  4. Address other comments
>
> Changelog v5:
>  1. Change wakeup and stop function pointers in struct vhost_worker to void.
>  2. merging patches 4, 5, 6 in a single patch
>  3. Fix spelling issues and address other comments.
>
> Tested with QEMU with kthread mode/task mode/kthread+task mode
>
> Cindy Lu (6):
>   vhost: Add a new parameter in vhost_dev to allow user select kthread
>   vhost: Add the vhost_worker to support kthread
>   vhost: Add the cgroup related function
>   vhost: Add worker related functions to support kthread
>   vhost: Add new UAPI to support change to task mode
>   vhost_scsi: Add check for inherit_owner status
>
>  drivers/vhost/scsi.c       |   8 ++
>  drivers/vhost/vhost.c      | 178 +++++++++++++++++++++++++++++++++----
>  drivers/vhost/vhost.h      |   4 +
>  include/uapi/linux/vhost.h |  19 ++++
>  4 files changed, 192 insertions(+), 17 deletions(-)
>
> --
> 2.45.0
>
>