[PATCH 0/2] drm/syncobj: add syncobj sideband payload for threaded submission

[Koenig, Christian]

Well first of all I strongly suggest to make the sideband information a 
separate IOCTL and not use the existing signal/query IOCTLs for it.

Then as far as I see this basically sets a sequence number to use for 
binary semaphores, is that correct? If yes then that would be a rather 
elegant idea.

Christian.

Am 07.08.19 um 15:37 schrieb Lionel Landwerlin:
> Hi,
>
> The goal of this feature is to solve an issue that was seen in our
> testing. After discussing on [1] I thought we could solve this problem
> with stalling the application thread after each vkQueueSubmit() call
> where a binary semaphore is signaled but I don't think it's a good
> option because of performance impacts on the application.
>
> Unfortunately there isn't a good way to reproduce this problem 100%
> because it essentially exposes a race between the application thread
> and the submission thread.
>
> I've uploaded tests in the Khronos repository to try to expose the
> issue.
>
> Thanks,
>
> [1] : https://lists.freedesktop.org/archives/dri-devel/2019-August/229188.html
>
> Lionel Landwerlin (2):
>    drm/syncobj: add sideband payload
>    drm/syncobj: add submit point query capability
>
>   drivers/gpu/drm/drm_syncobj.c | 132 ++++++++++++++++++++++------------
>   include/drm/drm_syncobj.h     |   9 +++
>   include/uapi/drm/drm.h        |   5 +-
>   3 files changed, 100 insertions(+), 46 deletions(-)
>
> --
> 2.23.0.rc1