On Fri, Mar 17, 2023 at 12:08 PM Faith Ekstrand <fa...@gfxstrand.net> wrote:
>
>
> On Wed, Mar 8, 2023 at 9:54 AM Rob Clark <robdcl...@gmail.com> wrote:
>>
>> From: Rob Clark <robdcl...@chromium.org>
>>
>> Add a new flag to let userspace provide a deadline as a hint for syncobj
>> and timeline waits. This gives a hint to the driver signaling the
>> backing fences about how soon userspace needs it to compete work, so it
>> can addjust GPU frequency accordingly. An immediate deadline can be
>> given to provide something equivalent to i915 "wait boost".
>>
>> v2: Use absolute u64 ns value for deadline hint, drop cap and driver
>> feature flag in favor of allowing count_handles==0 as a way for
>> userspace to probe kernel for support of new flag
>> v3: More verbose comments about UAPI
>>
>> Signed-off-by: Rob Clark <robdcl...@chromium.org>
>> ---
>> drivers/gpu/drm/drm_syncobj.c | 64 ++++++++++++++++++++++++++++-------
>> include/uapi/drm/drm.h | 17 ++++++++++
>> 2 files changed, 68 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
>> index 0c2be8360525..a85e9464f07b 100644
>> --- a/drivers/gpu/drm/drm_syncobj.c
>> +++ b/drivers/gpu/drm/drm_syncobj.c
>> @@ -126,6 +126,11 @@
>> * synchronize between the two.
>> * This requirement is inherited from the Vulkan fence API.
>> *
>> + * If &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE is set, the ioctl will also set
>> + * a fence deadline hint on the backing fences before waiting, to provide
>> the
>> + * fence signaler with an appropriate sense of urgency. The deadline is
>> + * specified as an absolute &CLOCK_MONOTONIC value in units of ns.
>> + *
>> * Similarly, &DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT takes an array of syncobj
>> * handles as well as an array of u64 points and does a host-side wait on
>> all
>> * of syncobj fences at the given points simultaneously.
>> @@ -973,7 +978,8 @@ static signed long drm_syncobj_array_wait_timeout(struct
>> drm_syncobj **syncobjs,
>> uint32_t count,
>> uint32_t flags,
>> signed long timeout,
>> - uint32_t *idx)
>> + uint32_t *idx,
>> + ktime_t *deadline)
>> {
>> struct syncobj_wait_entry *entries;
>> struct dma_fence *fence;
>> @@ -1053,6 +1059,15 @@ static signed long
>> drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
>> drm_syncobj_fence_add_wait(syncobjs[i], &entries[i]);
>> }
>>
>> + if (deadline) {
>> + for (i = 0; i < count; ++i) {
>> + fence = entries[i].fence;
>> + if (!fence)
>> + continue;
>> + dma_fence_set_deadline(fence, *deadline);
>> + }
>> + }
>> +
>> do {
>> set_current_state(TASK_INTERRUPTIBLE);
>>
>> @@ -1151,7 +1166,8 @@ static int drm_syncobj_array_wait(struct drm_device
>> *dev,
>> struct drm_file *file_private,
>> struct drm_syncobj_wait *wait,
>> struct drm_syncobj_timeline_wait
>> *timeline_wait,
>> - struct drm_syncobj **syncobjs, bool
>> timeline)
>> + struct drm_syncobj **syncobjs, bool
>> timeline,
>> + ktime_t *deadline)
>> {
>> signed long timeout = 0;
>> uint32_t first = ~0;
>> @@ -1162,7 +1178,8 @@ static int drm_syncobj_array_wait(struct drm_device
>> *dev,
>> NULL,
>> wait->count_handles,
>> wait->flags,
>> - timeout, &first);
>> + timeout, &first,
>> + deadline);
>> if (timeout < 0)
>> return timeout;
>> wait->first_signaled = first;
>> @@ -1172,7 +1189,8 @@ static int drm_syncobj_array_wait(struct drm_device
>> *dev,
>>
>> u64_to_user_ptr(timeline_wait->points),
>>
>> timeline_wait->count_handles,
>>
>> timeline_wait->flags,
>> - timeout, &first);
>> + timeout, &first,
>> + deadline);
>> if (timeout < 0)
>> return timeout;
>> timeline_wait->first_signaled = first;
>> @@ -1243,17 +1261,22 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void
>> *data,
>> {
>> struct drm_syncobj_wait *args = data;
>> struct drm_syncobj **syncobjs;
>> + unsigned possible_flags;
>> + ktime_t t, *tp = NULL;
>> int ret = 0;
>>
>> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
>> return -EOPNOTSUPP;
>>
>> - if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
>> - DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
>> + possible_flags = DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE;
>> +
>> + if (args->flags & ~possible_flags)
>> return -EINVAL;
>>
>> if (args->count_handles == 0)
>> - return -EINVAL;
>> + return 0;
>
>
> Did you intend this change? If so, why? What does waiting with no handles
> gain us? I mean, it's probably fine but it seems unrelated to this change.
Yes, it was intentional.. it gives userspace a way to probe whether
the kernel supports the new flag..
BR,
-R
>> ret = drm_syncobj_array_find(file_private,
>> u64_to_user_ptr(args->handles),
>> @@ -1262,8 +1285,13 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void
>> *data,
>> if (ret < 0)
>> return ret;
>>
>> + if (args->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE) {
>> + t = ns_to_ktime(args->deadline_ns);
>> + tp = &t;
>> + }
>> +
>> ret = drm_syncobj_array_wait(dev, file_private,
>> - args, NULL, syncobjs, false);
>> + args, NULL, syncobjs, false, tp);
>>
>> drm_syncobj_array_free(syncobjs, args->count_handles);
>>
>> @@ -1276,18 +1304,23 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device
>> *dev, void *data,
>> {
>> struct drm_syncobj_timeline_wait *args = data;
>> struct drm_syncobj **syncobjs;
>> + unsigned possible_flags;
>> + ktime_t t, *tp = NULL;
>> int ret = 0;
>>
>> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>> return -EOPNOTSUPP;
>>
>> - if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
>> - DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
>> - DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE))
>> + possible_flags = DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE |
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE;
>> +
>> + if (args->flags & ~possible_flags)
>> return -EINVAL;
>>
>> if (args->count_handles == 0)
>> - return -EINVAL;
>> + return -0;
>
>
> Did you intend this change? -0 is a pretty weird integer.
>
>>
>> ret = drm_syncobj_array_find(file_private,
>> u64_to_user_ptr(args->handles),
>> @@ -1296,8 +1329,13 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device
>> *dev, void *data,
>> if (ret < 0)
>> return ret;
>>
>> + if (args->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE) {
>> + t = ns_to_ktime(args->deadline_ns);
>> + tp = &t;
>> + }
>> +
>> ret = drm_syncobj_array_wait(dev, file_private,
>> - NULL, args, syncobjs, true);
>> + NULL, args, syncobjs, true, tp);
>>
>> drm_syncobj_array_free(syncobjs, args->count_handles);
>>
>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>> index 642808520d92..bff0509ac8b6 100644
>> --- a/include/uapi/drm/drm.h
>> +++ b/include/uapi/drm/drm.h
>> @@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
>> #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
>> #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
>> #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time
>> point to become available */
>> +#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline
>> based to deadline_ns */
>> struct drm_syncobj_wait {
>> __u64 handles;
>> /* absolute timeout */
>> @@ -895,6 +896,14 @@ struct drm_syncobj_wait {
>> __u32 flags;
>> __u32 first_signaled; /* only valid when not waiting all */
>> __u32 pad;
>> + /**
>> + * @deadline_ns - fence deadline hint
>> + *
>> + * Deadline hint, in absolute CLOCK_MONOTONIC, to set on backing
>> + * fence(s) if the DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE flag is
>> + * set.
>> + */
>> + __u64 deadline_ns;
>> };
>>
>> struct drm_syncobj_timeline_wait {
>> @@ -907,6 +916,14 @@ struct drm_syncobj_timeline_wait {
>> __u32 flags;
>> __u32 first_signaled; /* only valid when not waiting all */
>> __u32 pad;
>> + /**
>> + * @deadline_ns - fence deadline hint
>> + *
>> + * Deadline hint, in absolute CLOCK_MONOTONIC, to set on backing
>> + * fence(s) if the DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE flag is
>> + * set.
>> + */
>> + __u64 deadline_ns;
>> };
>>
>>
>> --
>> 2.39.2
>>
