回复：[PATCH v3 1/1] drm/syncobj: add sideband payload
Zhou, David(ChunMing)
David1.Zhou at amd.com
Thu Aug 8 15:23:13 UTC 2019
Thank you, I got your mean.
when you have sideband payload, you will go into timeline path. Clever!
-David
-------- 原始邮件 --------
主题：Re: [PATCH v3 1/1] drm/syncobj: add sideband payload
发件人：Lionel Landwerlin
收件人："Zhou, David(ChunMing)" ,dri-devel at freedesktop.org
抄送："Koenig, Christian" ,Jason Ekstrand ,"Zhou, David(ChunMing)"
On 08/08/2019 17:48, Chunming Zhou wrote:
> 在 2019/8/8 22:34, Lionel Landwerlin 写道:
>> On 08/08/2019 17:16, Chunming Zhou wrote:
>>> 在 2019/8/8 22:01, Lionel Landwerlin 写道:
>>>> On 08/08/2019 16:42, Chunming Zhou wrote:
>>>>> No, I just see your comment "The next vkQueueSubmit()
>>>>> waiting on a the syncobj will read the sideband payload and wait for a
>>>>> fence chain element with a seqno superior or equal to the sideband
>>>>> payload value to be added into the fence chain and use that fence to
>>>>> trigger the submission on the kernel driver. ".
>>>> That was meant to say wait on the chain fence to reach the sideband
>>>> payload value.
>>>>
>>>> It a bit confusing but I can't see any other way to word it.
>>>>
>>>>
>>>>> In that, you mentioned wait for sideband.
>>>>> So I want to know we how to use that, maybe I miss something in
>>>>> previous
>>>>> discussing thread.
>>>> In QueueSubmit(), we start by reading the sideband payloads :
>>>> https://gitlab.freedesktop.org/llandwerlin/mesa/blob/review/anv-timeline_semaphore_prep/src/intel/vulkan/anv_queue.c#L655
>>>>
>>>>
>>>> Then build everything for the submission and hand it over to the
>>>> submission thread.
>>>>
>>>> Instead of the just waiting on the timeline semaphore values, we also
>>>> wait on the binary semaphore sideband payload values.
>>> Waiting on timeline values is when finding fence in kernel.
>>
>> Hmm aren't you waiting in a thread in userspace?
> Yes, For timeline case, we can use waitForSyncobj()..., At begin of
> QueueThread, I let it wait in cs_ioctl when drm_syncobj_find_fence.
>
> But I still didn't get how to wait on sideband for binary Syncobj.
>
> Ah, I see, you will compare it in your QueueThread, if sideband value is
> >= expected, then do submission, otherwise, loop QueueThread, right?
Just treat binary semaphores as timelines and waitForSyncobj on the
sideband payload value.
It should make the submission thread any busier than currently.
-Lionel
>
> That sounds the QueueThread will be always busy.
>
> -David
>
>
>>
>>> But I don't see how to wait/block in kernel when finding fence for
>>> binary sideband payload values.
>>
>> Essentially our driver now handles timelines & binary semaphore using
>> dma-fence-chain in both cases.
>
>
>> Only with timelines we take the values submitted by the vulkan
>> application.
>
>> The binary semaphore auto increment on vkQueueSubmit() and that is
>> managed by the userspace driver.
>>
>>
>> -Lionel
>>
>>
>>>
>>> -David
>>>
>>>> Finally before exiting the QueueSubmit() call, we bump the sideband
>>>> payloads of all the binary semaphores have have been signaled :
>>>> https://gitlab.freedesktop.org/llandwerlin/mesa/blob/review/anv-timeline_semaphore_prep/src/intel/vulkan/anv_queue.c#L806
>>>>
>>>>
>>>>
>>>> Whoever calls QueueSubmit() after that will pickup the new sideband
>>>> payload values to wait on.
>>>>
>>>>
>>>> -Lionel
>>>>
>>>>
>>>>
>>>>> -DAvid
>>>>>
>>>>>
>>>>> 在 2019/8/8 21:38, Lionel Landwerlin 写道:
>>>>>> Interesting question :)
>>>>>>
>>>>>> I didn't see any usecase for that.
>>>>>> This sideband payload value is used for a wait so waiting on the wait
>>>>>> value for another wait is bit meta :)
>>>>>>
>>>>>> Do you have a use case for that?
>>>>>>
>>>>>> -Lionel
>>>>>>
>>>>>> On 08/08/2019 16:23, Chunming Zhou wrote:
>>>>>>> The propursal is fine with me.
>>>>>>>
>>>>>>> one question:
>>>>>>>
>>>>>>> how to wait sideband payload? Following patch will show that?
>>>>>>>
>>>>>>> -David
>>>>>>>
>>>>>>> 在 2019/8/8 21:14, Lionel Landwerlin 写道:
>>>>>>>> The Vulkan timeline semaphores allow signaling to happen on the
>>>>>>>> point
>>>>>>>> of the timeline without all of the its dependencies to be created.
>>>>>>>>
>>>>>>>> The current 2 implementations (AMD/Intel) of the Vulkan spec on
>>>>>>>> top of
>>>>>>>> the Linux kernel are using a thread to wait on the dependencies
>>>>>>>> of a
>>>>>>>> given point to materialize and delay actual submission to the
>>>>>>>> kernel
>>>>>>>> driver until the wait completes.
>>>>>>>>
>>>>>>>> If a binary semaphore is submitted for signaling along the side
>>>>>>>> of a
>>>>>>>> timeline semaphore waiting for completion that means that the drm
>>>>>>>> syncobj associated with that binary semaphore will not have a DMA
>>>>>>>> fence associated with it by the time vkQueueSubmit() returns. This
>>>>>>>> and
>>>>>>>> the fact that a binary semaphore can be signaled and unsignaled as
>>>>>>>> before its DMA fences materialize mean that we cannot just rely on
>>>>>>>> the
>>>>>>>> fence within the syncobj but we also need a sideband payload
>>>>>>>> verifying
>>>>>>>> that the fence in the syncobj matches the last submission from the
>>>>>>>> Vulkan API point of view.
>>>>>>>>
>>>>>>>> This change adds a sideband payload that is incremented with
>>>>>>>> signaled
>>>>>>>> syncobj when vkQueueSubmit() is called. The next vkQueueSubmit()
>>>>>>>> waiting on a the syncobj will read the sideband payload and wait
>>>>>>>> for a
>>>>>>>> fence chain element with a seqno superior or equal to the sideband
>>>>>>>> payload value to be added into the fence chain and use that
>>>>>>>> fence to
>>>>>>>> trigger the submission on the kernel driver.
>>>>>>>>
>>>>>>>> v2: Use a separate ioctl to get/set the sideband value (Christian)
>>>>>>>>
>>>>>>>> v3: Use 2 ioctls for get/set (Christian)
>>>>>>>>
>>>>>>>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>>>>>>> Cc: Christian Koenig <Christian.Koenig at amd.com>
>>>>>>>> Cc: Jason Ekstrand <jason at jlekstrand.net>
>>>>>>>> Cc: David(ChunMing) Zhou <David1.Zhou at amd.com>
>>>>>>>> ---
>>>>>>>> drivers/gpu/drm/drm_internal.h | 4 ++
>>>>>>>> drivers/gpu/drm/drm_ioctl.c | 5 +++
>>>>>>>> drivers/gpu/drm/drm_syncobj.c | 79
>>>>>>>> +++++++++++++++++++++++++++++++++-
>>>>>>>> include/drm/drm_syncobj.h | 9 ++++
>>>>>>>> include/uapi/drm/drm.h | 2 +
>>>>>>>> 5 files changed, 98 insertions(+), 1 deletion(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/drm_internal.h
>>>>>>>> b/drivers/gpu/drm/drm_internal.h
>>>>>>>> index 51a2055c8f18..0c9736199df0 100644
>>>>>>>> --- a/drivers/gpu/drm/drm_internal.h
>>>>>>>> +++ b/drivers/gpu/drm/drm_internal.h
>>>>>>>> @@ -208,6 +208,10 @@ int drm_syncobj_timeline_signal_ioctl(struct
>>>>>>>> drm_device *dev, void *data,
>>>>>>>> struct drm_file *file_private);
>>>>>>>> int drm_syncobj_query_ioctl(struct drm_device *dev, void
>>>>>>>> *data,
>>>>>>>> struct drm_file *file_private);
>>>>>>>> +int drm_syncobj_get_sideband_ioctl(struct drm_device *dev, void
>>>>>>>> *data,
>>>>>>>> + struct drm_file *file_private);
>>>>>>>> +int drm_syncobj_set_sideband_ioctl(struct drm_device *dev, void
>>>>>>>> *data,
>>>>>>>> + struct drm_file *file_private);
>>>>>>>> /* drm_framebuffer.c */
>>>>>>>> void drm_framebuffer_print_info(struct drm_printer *p,
>>>>>>>> unsigned
>>>>>>>> int indent,
>>>>>>>> diff --git a/drivers/gpu/drm/drm_ioctl.c
>>>>>>>> b/drivers/gpu/drm/drm_ioctl.c
>>>>>>>> index f675a3bb2c88..48500bf62801 100644
>>>>>>>> --- a/drivers/gpu/drm/drm_ioctl.c
>>>>>>>> +++ b/drivers/gpu/drm/drm_ioctl.c
>>>>>>>> @@ -703,6 +703,11 @@ static const struct drm_ioctl_desc
>>>>>>>> drm_ioctls[]
>>>>>>>> = {
>>>>>>>> DRM_RENDER_ALLOW),
>>>>>>>> DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_QUERY,
>>>>>>>> drm_syncobj_query_ioctl,
>>>>>>>> DRM_RENDER_ALLOW),
>>>>>>>> + DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_GET_SIDEBAND,
>>>>>>>> drm_syncobj_get_sideband_ioctl,
>>>>>>>> + DRM_RENDER_ALLOW),
>>>>>>>> + DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_SET_SIDEBAND,
>>>>>>>> drm_syncobj_set_sideband_ioctl,
>>>>>>>> + DRM_RENDER_ALLOW),
>>>>>>>> +
>>>>>>>> DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE,
>>>>>>>> drm_crtc_get_sequence_ioctl, 0),
>>>>>>>> DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE,
>>>>>>>> drm_crtc_queue_sequence_ioctl, 0),
>>>>>>>> DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE,
>>>>>>>> drm_mode_create_lease_ioctl, DRM_MASTER),
>>>>>>>> diff --git a/drivers/gpu/drm/drm_syncobj.c
>>>>>>>> b/drivers/gpu/drm/drm_syncobj.c
>>>>>>>> index b927e482e554..c90ef20b9242 100644
>>>>>>>> --- a/drivers/gpu/drm/drm_syncobj.c
>>>>>>>> +++ b/drivers/gpu/drm/drm_syncobj.c
>>>>>>>> @@ -1150,8 +1150,10 @@ drm_syncobj_reset_ioctl(struct drm_device
>>>>>>>> *dev, void *data,
>>>>>>>> if (ret < 0)
>>>>>>>> return ret;
>>>>>>>> - for (i = 0; i < args->count_handles; i++)
>>>>>>>> + for (i = 0; i < args->count_handles; i++) {
>>>>>>>> drm_syncobj_replace_fence(syncobjs[i], NULL);
>>>>>>>> + syncobjs[i]->sideband_payload = 0;
>>>>>>>> + }
>>>>>>>> drm_syncobj_array_free(syncobjs, args->count_handles);
>>>>>>>> @@ -1321,6 +1323,81 @@ int drm_syncobj_query_ioctl(struct
>>>>>>>> drm_device *dev, void *data,
>>>>>>>> if (ret)
>>>>>>>> break;
>>>>>>>> }
>>>>>>>> +
>>>>>>>> + drm_syncobj_array_free(syncobjs, args->count_handles);
>>>>>>>> +
>>>>>>>> + return ret;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +int drm_syncobj_get_sideband_ioctl(struct drm_device *dev, void
>>>>>>>> *data,
>>>>>>>> + struct drm_file *file_private)
>>>>>>>> +{
>>>>>>>> + struct drm_syncobj_timeline_array *args = data;
>>>>>>>> + struct drm_syncobj **syncobjs;
>>>>>>>> + uint64_t __user *points = u64_to_user_ptr(args->points);
>>>>>>>> + uint32_t i;
>>>>>>>> + int ret;
>>>>>>>> +
>>>>>>>> + if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>>>>>>>> + return -EOPNOTSUPP;
>>>>>>>> +
>>>>>>>> + if (args->pad != 0)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + if (args->count_handles == 0)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + ret = drm_syncobj_array_find(file_private,
>>>>>>>> + u64_to_user_ptr(args->handles),
>>>>>>>> + args->count_handles,
>>>>>>>> + &syncobjs);
>>>>>>>> + if (ret < 0)
>>>>>>>> + return ret;
>>>>>>>> +
>>>>>>>> + for (i = 0; i < args->count_handles; i++) {
>>>>>>>> + copy_to_user(&points[i], &syncobjs[i]->sideband_payload,
>>>>>>>> sizeof(uint64_t));
>>>>>>>> + ret = ret ? -EFAULT : 0;
>>>>>>>> + if (ret)
>>>>>>>> + break;
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> + drm_syncobj_array_free(syncobjs, args->count_handles);
>>>>>>>> +
>>>>>>>> + return ret;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +int drm_syncobj_set_sideband_ioctl(struct drm_device *dev, void
>>>>>>>> *data,
>>>>>>>> + struct drm_file *file_private)
>>>>>>>> +{
>>>>>>>> + struct drm_syncobj_timeline_array *args = data;
>>>>>>>> + struct drm_syncobj **syncobjs;
>>>>>>>> + uint64_t __user *points = u64_to_user_ptr(args->points);
>>>>>>>> + uint32_t i;
>>>>>>>> + int ret;
>>>>>>>> +
>>>>>>>> + if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>>>>>>>> + return -EOPNOTSUPP;
>>>>>>>> +
>>>>>>>> + if (args->pad != 0)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + if (args->count_handles == 0)
>>>>>>>> + return -EINVAL;
>>>>>>>> +
>>>>>>>> + ret = drm_syncobj_array_find(file_private,
>>>>>>>> + u64_to_user_ptr(args->handles),
>>>>>>>> + args->count_handles,
>>>>>>>> + &syncobjs);
>>>>>>>> + if (ret < 0)
>>>>>>>> + return ret;
>>>>>>>> +
>>>>>>>> + for (i = 0; i < args->count_handles; i++) {
>>>>>>>> + copy_from_user(&syncobjs[i]->sideband_payload, &points[i],
>>>>>>>> sizeof(uint64_t));
>>>>>>>> + ret = ret ? -EFAULT : 0;
>>>>>>>> + if (ret)
>>>>>>>> + break;
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> drm_syncobj_array_free(syncobjs, args->count_handles);
>>>>>>>> return ret;
>>>>>>>> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
>>>>>>>> index 6cf7243a1dc5..b587b8e07547 100644
>>>>>>>> --- a/include/drm/drm_syncobj.h
>>>>>>>> +++ b/include/drm/drm_syncobj.h
>>>>>>>> @@ -61,6 +61,15 @@ struct drm_syncobj {
>>>>>>>> * @file: A file backing for this syncobj.
>>>>>>>> */
>>>>>>>> struct file *file;
>>>>>>>> + /**
>>>>>>>> + * @sideband_payload: A 64bit side band payload.
>>>>>>>> + *
>>>>>>>> + * We use the sideband payload value to wait on binary syncobj
>>>>>>>> fences
>>>>>>>> + * to materialize. It is a reservation mechanism for the
>>>>>>>> signaler to
>>>>>>>> + * express that at some point in the future a dma fence with
>>>>>>>> the same
>>>>>>>> + * seqno will be put into the syncobj.
>>>>>>>> + */
>>>>>>>> + u64 sideband_payload;
>>>>>>>> };
>>>>>>>> void drm_syncobj_free(struct kref *kref);
>>>>>>>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>>>>>>>> index 8a5b2f8f8eb9..cffdc6c9772c 100644
>>>>>>>> --- a/include/uapi/drm/drm.h
>>>>>>>> +++ b/include/uapi/drm/drm.h
>>>>>>>> @@ -946,6 +946,8 @@ extern "C" {
>>>>>>>> #define DRM_IOCTL_SYNCOBJ_QUERY DRM_IOWR(0xCB, struct
>>>>>>>> drm_syncobj_timeline_array)
>>>>>>>> #define DRM_IOCTL_SYNCOBJ_TRANSFER DRM_IOWR(0xCC, struct
>>>>>>>> drm_syncobj_transfer)
>>>>>>>> #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD,
>>>>>>>> struct drm_syncobj_timeline_array)
>>>>>>>> +#define DRM_IOCTL_SYNCOBJ_GET_SIDEBAND DRM_IOR(0xCE, struct
>>>>>>>> drm_syncobj_timeline_array)
>>>>>>>> +#define DRM_IOCTL_SYNCOBJ_SET_SIDEBAND DRM_IOWR(0xCF, struct
>>>>>>>> drm_syncobj_timeline_array)
>>>>>>>> /**
>>>>>>>> * Device specific ioctls should only be in their respective
>>>>>>>> headers
>>
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