The open source OpenXR runtime
a/util: Frame pacing docs and some error handling
authored by
Ryan Pavlik
and committed by
Jakob Bornecrantz
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src/xrt/auxiliary/util/u_pacing_compositor.c
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src/xrt/auxiliary/util/u_pacing_compositor.c
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// Copyright 2020-2021, Collabora, Ltd.
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// Copyright 2020-2022, Collabora, Ltd.
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// SPDX-License-Identifier: BSL-1.0
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/*!
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* @file
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return is_within_of_each_other(l, r, U_TIME_HALF_MS_IN_NS);
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}
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/*!
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* Gets a frame data structure based on the @p frame_id.
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*
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* Note that this is done modulo the number of frame data structs we hold: the data in the frame you receive may not
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* match the @p frame_id you passed!
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*
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* @see create_frame to create a frame id and (partially) initialize the frame data structure, @ref do_clean_slate_frame
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* for a more complete initialization
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*/
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static struct frame *
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get_frame(struct display_timing *dt, int64_t frame_id)
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{
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return &dt->frames[index];
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}
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/*!
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* Assign the next available frame ID, initialize the corresponding frame data with the ID and @p state, and return a
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* pointer to that frame data.
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*
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* Fields other than frame::frame_id and frame::state are not modified, so may have old data in them. This may be a
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* feature rather than a bug.
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*/
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static struct frame *
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create_frame(struct display_timing *dt, enum frame_state state)
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{
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return f;
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}
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/*!
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* Gets the most recent frame data whose state is greater than or equal to @p state, if any
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*
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* @return a frame pointer, or null if no frames have at least @p state
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*/
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static struct frame *
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get_latest_frame_with_state_at_least(struct display_timing *dt, enum frame_state state)
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{
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return NULL;
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}
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/*!
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* "Create" a frame ID in state @ref STATE_PREDICTED (by calling @ref create_frame), and additionally initialize
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* frame::desired_present_time_ns (with a crude estimate) and frame::when_predict_ns.
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*/
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static struct frame *
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do_clean_slate_frame(struct display_timing *dt)
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{
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return f;
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}
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/*!
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* Find the next possible present time for rendering that has not yet occurred, and create a frame/frame id with that
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* prediction in it.
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*/
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static struct frame *
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walk_forward_through_frames(struct display_timing *dt, uint64_t last_present_time_ns)
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{
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uint64_t now_ns = os_monotonic_get_ns();
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// This is the earliest possible time we could present, assuming rendering still must take place.
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uint64_t from_time_ns = now_ns + calc_total_app_time(dt);
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uint64_t desired_present_time_ns = last_present_time_ns + dt->frame_period_ns;
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···
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struct frame *last = get_latest_frame_with_state_at_least(dt, STATE_INFO);
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struct frame *f = get_frame(dt, frame_id);
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if (f->frame_id != frame_id) {
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FT_LOG_W("Discarded info for unsubmitted or expired frame_id %" PRIx64, frame_id);
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if (last != NULL) {
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FT_LOG_W("The latest frame_id we have info for is %" PRIx64, last->frame_id);
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}
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return;
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}
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assert(f->state == STATE_SUBMITTED);
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assert(f->desired_present_time_ns == desired_present_time_ns);
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f->when_infoed_ns = os_monotonic_get_ns();
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f->actual_present_time_ns = actual_present_time_ns;