| -- Copyright 2026 The Chromium Authors |
| -- Use of this source code is governed by a BSD-style license that can be |
| -- found in the LICENSE file. |
| |
| -- Finds the timestamps and durations of sub-slices of 'ScrollJankV4' main |
| -- slices with the given `sub_slice_names`. |
| -- |
| -- If available (in newer Chrome versions), we associate sub-slices with the |
| -- main slice based on the `scroll_jank_v4.result_id` argument. Otherwise (in |
| -- older Chrome versions), we associate sub-slices with the main slice based on |
| -- the `descendant_slice` operator instead. We prefer the former approach |
| -- because it's more robust. See below for more details. |
| -- |
| -- The returned table is guaranteed to contain at most one row for each |
| -- 'ScrollJankV4' slice ID in `scroll_jank_v4_slice`. |
| CREATE PERFETTO MACRO _chrome_scroll_jank_v4_sub_slice( |
| -- Table which contains slice `id`s and `result_id`s (NULL if not available) |
| -- of 'SliceJankV4' slices. |
| scroll_jank_v4_slice TableOrSubquery, |
| -- Table which indicates whether `scroll_jank_v4.result_id` arguments are |
| -- available in the trace. Non-empty if they're available. Empty if they're |
| -- not available. |
| has_result_id TableOrSubquery, |
| -- The possible names of the sub-slices to filter for. |
| sub_slice_names Expr |
| ) |
| RETURNS TableOrSubquery AS |
| ( |
| WITH |
| branches AS ( |
| -- Main logic (newer Chrome versions): Associate sub-slices with the main |
| -- slice based on the `scroll_jank_v4.result_id` argument. |
| SELECT |
| * |
| FROM ( |
| SELECT |
| main_slice.id, |
| sub_slice.ts, |
| sub_slice.dur |
| FROM $scroll_jank_v4_slice AS main_slice |
| JOIN args AS result_id_arg |
| ON result_id_arg.int_value = main_slice.result_id |
| AND result_id_arg.key = 'scroll_jank_v4.result_id' |
| JOIN slice AS sub_slice |
| ON sub_slice.arg_set_id = result_id_arg.arg_set_id |
| AND sub_slice.id != main_slice.id |
| AND sub_slice.name IN $sub_slice_names |
| ) |
| WHERE |
| EXISTS( |
| SELECT |
| 1 |
| FROM $has_result_id |
| ) |
| UNION ALL |
| -- Fallback logic (older Chrome versions): Associate sub-slices with the |
| -- main slice based on the `descendant_slice` operator. This usually |
| -- doesn't work for the final instant sub-slice ("Presentation", |
| -- "Extrapolated presentation" or "Begin frame") due to |
| -- https://github.com/google/perfetto/issues/4880. |
| SELECT |
| * |
| FROM ( |
| SELECT |
| main_slice.id, |
| sub_slice.ts, |
| sub_slice.dur |
| FROM $scroll_jank_v4_slice AS main_slice, descendant_slice(main_slice.id) AS sub_slice |
| WHERE |
| sub_slice.name IN $sub_slice_names |
| ) |
| WHERE |
| NOT EXISTS( |
| SELECT |
| 1 |
| FROM $has_result_id |
| ) |
| ) |
| -- Select the first sub-slice for each main slice to avoid double counting |
| -- 'ScrollJankV4' slices. |
| SELECT |
| id, |
| min(ts) AS ts, |
| -- Note: SQLite documentation guarantees to choose a `dur` from a row that |
| -- has `MIN(ts)`. See |
| -- https://sqlite.org/lang_select.html#bare_columns_in_an_aggregate_query. |
| dur |
| FROM branches |
| GROUP BY |
| id |
| ); |
| |
| -- Results of the Scroll Jank V4 metric for frames which contain one or more |
| -- scroll updates. |
| -- |
| -- See |
| -- https://docs.google.com/document/d/1AaBvTIf8i-c-WTKkjaL4vyhQMkSdynxo3XEiwpofdeA |
| -- and `EventLatency.ScrollJankV4Result` in |
| -- https://source.chromium.org/chromium/chromium/src/+/main:base/tracing/protos/chrome_track_event.proto |
| -- for more information. |
| -- |
| -- Available since Chrome 145.0.7573.0 and cherry-picked into 144.0.7559.31. |
| CREATE PERFETTO TABLE chrome_scroll_jank_v4_results ( |
| -- Slice ID of the 'ScrollJankV4' slice. |
| id ID(slice.id), |
| -- Slice name ('ScrollJankV4'). |
| name STRING, |
| -- The timestamp at the start of the slice. |
| ts TIMESTAMP, |
| -- The duration of the slice. |
| dur DURATION, |
| -- ID of this frame's result. |
| result_id LONG, |
| -- Whether this frame is janky. True if and only if there's at least one row |
| -- with `id` in `chrome_scroll_jank_v4_reasons`. If true, then |
| -- `vsyncs_since_previous_frame` must be greater than one. |
| is_janky BOOL, |
| -- How many VSyncs were between (A) this frame and (B) the previous frame. |
| -- If this value is greater than one, then Chrome potentially missed one or |
| -- more VSyncs (i.e. might have been able to present this scroll update |
| -- earlier). NULL if this frame is the first frame in a scroll. |
| vsyncs_since_previous_frame LONG, |
| -- The running delivery cut-off based on frames preceding this frame. NULL |
| -- if ANY of the following holds: |
| -- |
| -- * This frame is the first frame in a scroll. |
| -- * All frames since the beginning of the scroll up to and including the |
| -- previous frame have been non-damaging. |
| -- * The most recent janky frame was non-damaging and all frames since |
| -- then up to and including the previous frame have been non-damaging. |
| running_delivery_cutoff DURATION, |
| -- The running delivery cut-off adjusted for this frame. NULL if ANY of the |
| -- following holds: |
| -- |
| -- * This frame is the first frame in a scroll. |
| -- * This frame is non-damaging. |
| -- * All frames since the beginning of the scroll up to and including the |
| -- previous frame have been non-damaging. |
| -- * The most recent janky frame was non-damaging and all frames since |
| -- then up to and including the previous frame have been non-damaging. |
| -- * `vsyncs_since_previous_frame` is equal to one. |
| adjusted_delivery_cutoff DURATION, |
| -- The delivery cut-off of this frame. NULL if this frame is non-damaging. |
| current_delivery_cutoff DURATION, |
| -- Trace ID of the first real scroll update included in this frame. Can be |
| -- joined with `chrome_event_latencies.scroll_update_id`. NULL if this frame |
| -- contains no real scroll updates. |
| real_first_event_latency_id LONG, |
| -- The actual generation timestamp of the first real scroll update included |
| -- (coalesced) in this frame. NULL if this frame contains no real scroll |
| -- updates. |
| real_first_input_generation_ts TIMESTAMP, |
| -- The actual generation timestamp of the last real scroll update included |
| -- (coalesced) in this frame. NULL if this frame contains no real scroll |
| -- updates. |
| real_last_input_generation_ts TIMESTAMP, |
| -- The absolute total raw (unpredicted) delta of all real scroll updates |
| -- included in this frame (in pixels). NULL if this frame contains no real |
| -- scroll updates. |
| real_abs_total_raw_delta_pixels DOUBLE, |
| -- The maximum absolute raw (unpredicted) delta out of all inertial (fling) |
| -- scroll updates included in this frame (in pixels). NULL if there were no |
| -- inertial scroll updates in this frame. |
| real_max_abs_inertial_raw_delta_pixels DOUBLE, |
| -- Trace ID of the first synthetic scroll update included in this frame. Can |
| -- be joined with `chrome_event_latencies.scroll_update_id`. NULL if this |
| -- frame contains no synthetic scroll updates. |
| synthetic_first_event_latency_id LONG, |
| -- The generation timestamp of the first synthetic scroll update included |
| -- (coalesced) in this frame extrapolated based on the input generation → |
| -- begin frame duration of the most recent real scroll update. NULL if ANY of |
| -- the following holds: |
| -- |
| -- * This frame contains no synthetic scroll updates. |
| -- * This frame is janky (i.e. `is_janky` is true). |
| -- * All frames since the beginning of the scroll up to and including the |
| -- previous frame have contained only synthetic scroll updates. |
| -- * The most recent janky frame contained only synthetic scroll updates and |
| -- all frames since then up to and including the previous frame have |
| -- contained only synthetic scroll updates. |
| synthetic_first_extrapolated_input_generation_ts TIMESTAMP, |
| -- The begin frame timestamp of the first synthetic scroll update included |
| -- (coalesced) in this frame. NULL if this frame contains no synthetic scroll |
| -- updates. If not NULL, it's less than or equal to `begin_frame_ts`. |
| synthetic_first_original_begin_frame_ts TIMESTAMP, |
| -- Type of the first scroll update in this frame. Possible values: |
| -- |
| -- * 'REAL' |
| -- * 'SYNTHETIC_WITH_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP' |
| -- * 'SYNTHETIC_WITHOUT_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP' |
| -- |
| -- The first scroll update is decided as follows: |
| -- |
| -- * For real scroll updates, we consider their actual input generation |
| -- timestamp. |
| -- * For synthetic scroll updates, we extrapolate their input generation |
| -- timestamp based on the input generation → begin frame duration of the |
| -- most recent real scroll update UNLESS ANY of the following holds (in |
| -- which case we DON'T extrapolate input generation timestamps for |
| -- synthetic scroll updates in this frame): |
| -- * This frame is janky. |
| -- * All frames since the beginning of the scroll up to and |
| -- including the previous frame have contained only synthetic |
| -- scroll updates. |
| -- * The most recent janky frame contained only synthetic scroll |
| -- updates and all frames since then up to and including the |
| -- previous frame have contained only synthetic scroll updates. |
| -- |
| -- If, based on the above rules, the scroll update with the earliest input |
| -- generation timestamp is a real scroll update, then this frame's type is |
| -- 'REAL'. If the scroll update with the earliest input generation timestamp |
| -- is a synthetic scroll update, then this frame's type is |
| -- 'SYNTHETIC_WITH_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP'. |
| -- |
| -- If this frame contains only synthetic scroll updates but it wasn't |
| -- possible to extrapolate their input generation timestamp (for any of |
| -- the reasons listed above), then this frame's type is |
| -- 'SYNTHETIC_WITHOUT_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP'. |
| first_scroll_update_type STRING, |
| -- Trace ID of the first scroll update included in this frame. |
| -- |
| -- * If `first_scroll_update_type` is 'REAL', then `first_event_latency_id` |
| -- is equal to `real_first_event_latency_id`. |
| -- * If `first_scroll_update_type` is |
| -- 'SYNTHETIC_WITH_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP' or |
| -- 'SYNTHETIC_WITHOUT_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP', then |
| -- `first_event_latency_id` equal to `synthetic_first_event_latency_id`. |
| -- |
| -- Can be joined with `chrome_event_latencies.scroll_update_id`. |
| first_event_latency_id LONG, |
| -- Type of scroll damage in this frame. Possible values: |
| -- |
| -- * 'DAMAGING' |
| -- * 'NON_DAMAGING_WITH_EXTRAPOLATED_PRESENTATION_TIMESTAMP' |
| -- * 'NON_DAMAGING_WITHOUT_EXTRAPOLATED_PRESENTATION_TIMESTAMP' |
| -- |
| -- A frame F is non-damaging if the following conditions are BOTH true: |
| -- |
| -- 1. All scroll updates in F are non-damaging. A scroll update is |
| -- non-damaging if it didn't cause a frame update and/or didn't change |
| -- the scroll offset. |
| -- |
| -- 2. All frames between (both ends exclusive): |
| -- a. the last frame presented by Chrome before F and |
| -- b. F |
| -- are non-damaging. |
| -- |
| -- If this frame is damaging, its type is 'DAMAGING'. If this frame is |
| -- non-damaging and its presentation timestamp could be extrapolated based on |
| -- the begin frame → presentation duration of the most recent damaging frame, |
| -- its type is 'NON_DAMAGING_WITH_EXTRAPOLATED_PRESENTATION_TIMESTAMP'. |
| -- |
| -- If this frame is non-damaging and its presentation timestamp couldn't be |
| -- extrapolated for ANY of the reasons below, its type is |
| -- 'NON_DAMAGING_WITHOUT_EXTRAPOLATED_PRESENTATION_TIMESTAMP': |
| -- |
| -- * This frame is janky and non-damaging. |
| -- * All frames since the beginning of the scroll up to and including this |
| -- frame have been non-damaging. |
| -- * The most recent janky frame was non-damaging and all frames since |
| -- then up to and including the this frame have been non-damaging. |
| -- |
| -- Note: The `first_scroll_update_type` and `damage_type` columns are |
| -- orthogonal. The former depends on whether the frame is synthetic (only |
| -- contains synthetic scroll updates). The latter depends on whether the |
| -- frame is damaging. For example: |
| -- |
| -- * If a frame is synthetic and damaging, it will[1] have an extrapolated |
| -- input generation timestamp. |
| -- * If a frame is real and non-damaging, it will[1] have an extrapolated |
| -- presentation timestamp. |
| -- * If a frame is both synthetic and damaging, it will[1] have both |
| -- timestamps extrapolated. |
| -- |
| -- [1] As long as there's Chrome past performance to extrapolate based on. |
| damage_type STRING, |
| -- The VSync interval that this frame was produced for according to the |
| -- BeginFrameArgs. |
| vsync_interval DURATION, |
| -- The begin frame timestamp, at which this frame started, according to the |
| -- BeginFrameArgs. |
| -- |
| -- In older Chrome versions, this column is incorrectly NULL for frames whose |
| -- `damage_type` is |
| -- 'NON_DAMAGING_WITHOUT_EXTRAPOLATED_PRESENTATION_TIMESTAMP'. |
| begin_frame_ts TIMESTAMP, |
| -- The presentation timestamp of the frame. |
| -- |
| -- * If `damage_type` is 'DAMAGING', then `presentation_ts` is the actual |
| -- presentation timestamp. |
| -- * If `damage_type` is |
| -- 'NON_DAMAGING_WITH_EXTRAPOLATED_PRESENTATION_TIMESTAMP', then |
| -- `presentation_ts` is an extrapolated timestamp based on the begin frame |
| -- → presentation duration of the most recent damaging frame. |
| -- * If `damage_type` is |
| -- 'NON_DAMAGING_WITHOUT_EXTRAPOLATED_PRESENTATION_TIMESTAMP', then |
| -- `presentation_ts` is NULL. |
| -- |
| -- In older Chrome versions, this column is incorrectly always NULL. |
| presentation_ts TIMESTAMP |
| ) AS |
| WITH |
| scroll_jank_v4_slice AS ( |
| SELECT |
| id, |
| name, |
| ts, |
| dur, |
| extract_arg(arg_set_id, 'scroll_jank_v4.result_id') AS result_id, |
| extract_arg(arg_set_id, 'scroll_jank_v4.is_janky') AS is_janky, |
| extract_arg(arg_set_id, 'scroll_jank_v4.vsyncs_since_previous_frame') AS vsyncs_since_previous_frame, |
| extract_arg(arg_set_id, 'scroll_jank_v4.running_delivery_cutoff_us') AS running_delivery_cutoff, |
| extract_arg(arg_set_id, 'scroll_jank_v4.adjusted_delivery_cutoff_us') AS adjusted_delivery_cutoff, |
| extract_arg(arg_set_id, 'scroll_jank_v4.current_delivery_cutoff_us') AS current_delivery_cutoff, |
| extract_arg(arg_set_id, 'scroll_jank_v4.updates.real.first_event_latency_id') AS real_first_event_latency_id, |
| extract_arg(arg_set_id, 'scroll_jank_v4.updates.real.abs_total_raw_delta_pixels') AS real_abs_total_raw_delta_pixels, |
| extract_arg(arg_set_id, 'scroll_jank_v4.updates.real.max_abs_inertial_raw_delta_pixels') AS real_max_abs_inertial_raw_delta_pixels, |
| extract_arg(arg_set_id, 'scroll_jank_v4.updates.synthetic.first_event_latency_id') AS synthetic_first_event_latency_id, |
| extract_arg(arg_set_id, 'scroll_jank_v4.updates.first_scroll_update_type') AS first_scroll_update_type, |
| extract_arg(arg_set_id, 'scroll_jank_v4.damage_type') AS damage_type, |
| extract_arg(arg_set_id, 'scroll_jank_v4.vsync_interval_us') AS vsync_interval |
| FROM slice |
| WHERE |
| name = 'ScrollJankV4' |
| ), |
| has_result_id AS ( |
| SELECT |
| 1 |
| FROM scroll_jank_v4_slice |
| WHERE |
| result_id IS NOT NULL |
| LIMIT 1 |
| ) |
| SELECT |
| scroll_jank_v4_slice.id, |
| scroll_jank_v4_slice.name, |
| scroll_jank_v4_slice.ts, |
| scroll_jank_v4_slice.dur, |
| scroll_jank_v4_slice.result_id, |
| scroll_jank_v4_slice.is_janky, |
| scroll_jank_v4_slice.vsyncs_since_previous_frame, |
| scroll_jank_v4_slice.running_delivery_cutoff, |
| scroll_jank_v4_slice.adjusted_delivery_cutoff, |
| scroll_jank_v4_slice.current_delivery_cutoff, |
| scroll_jank_v4_slice.real_first_event_latency_id, |
| real_input_generation_slice.ts AS real_first_input_generation_ts, |
| real_input_generation_slice.ts + real_input_generation_slice.dur AS real_last_input_generation_ts, |
| scroll_jank_v4_slice.real_abs_total_raw_delta_pixels, |
| scroll_jank_v4_slice.real_max_abs_inertial_raw_delta_pixels, |
| scroll_jank_v4_slice.synthetic_first_event_latency_id, |
| synthetic_first_extrapolated_input_generation_slice.ts AS synthetic_first_extrapolated_input_generation_ts, |
| synthetic_first_original_begin_frame_slice.ts AS synthetic_first_original_begin_frame_ts, |
| scroll_jank_v4_slice.first_scroll_update_type, |
| CASE scroll_jank_v4_slice.first_scroll_update_type |
| WHEN 'REAL' |
| THEN real_first_event_latency_id |
| WHEN 'SYNTHETIC_WITH_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP' |
| THEN synthetic_first_event_latency_id |
| WHEN 'SYNTHETIC_WITHOUT_EXTRAPOLATED_INPUT_GENERATION_TIMESTAMP' |
| THEN synthetic_first_event_latency_id |
| ELSE coalesce(real_first_event_latency_id, synthetic_first_event_latency_id) |
| END AS first_event_latency_id, |
| scroll_jank_v4_slice.damage_type, |
| scroll_jank_v4_slice.vsync_interval, |
| begin_frame_slice.ts AS begin_frame_ts, |
| presentation_slice.ts AS presentation_ts |
| FROM scroll_jank_v4_slice |
| LEFT JOIN _chrome_scroll_jank_v4_sub_slice!(scroll_jank_v4_slice, has_result_id, ('Real scroll update input generation')) AS real_input_generation_slice |
| USING (id) |
| LEFT JOIN _chrome_scroll_jank_v4_sub_slice!(scroll_jank_v4_slice, has_result_id, ('Extrapolated first synthetic scroll update input generation')) AS synthetic_first_extrapolated_input_generation_slice |
| USING (id) |
| LEFT JOIN _chrome_scroll_jank_v4_sub_slice!(scroll_jank_v4_slice, has_result_id, ('First synthetic scroll update original begin frame')) AS synthetic_first_original_begin_frame_slice |
| USING (id) |
| LEFT JOIN _chrome_scroll_jank_v4_sub_slice!(scroll_jank_v4_slice, has_result_id, ('Begin frame')) AS begin_frame_slice |
| USING (id) |
| LEFT JOIN _chrome_scroll_jank_v4_sub_slice!(scroll_jank_v4_slice, has_result_id, ('Presentation', 'Extrapolated presentation')) AS presentation_slice |
| USING (id) |
| ORDER BY |
| scroll_jank_v4_slice.ts ASC; |
| |
| -- Reasons why the Scroll Jank V4 metric marked frames as janky. |
| -- |
| -- A frame might be janky for multiple reasons, so this table might contain |
| -- multiple rows with the same `id` and distinct `jank_reason`s. |
| -- |
| -- Available since Chrome 145.0.7573.0 and cherry-picked into 144.0.7559.31. |
| CREATE PERFETTO TABLE chrome_scroll_jank_v4_reasons ( |
| -- Slice ID of the 'ScrollJankV4' slice. Can be joined with |
| -- `chrome_scroll_jank_v4_results.id`. |
| id JOINID(slice.id), |
| -- A reason why the frame is janky. Possible values: |
| -- |
| -- * 'MISSED_VSYNC_DUE_TO_DECELERATING_INPUT_FRAME_DELIVERY': Chrome's |
| -- input→frame delivery slowed down to the point that it missed one or |
| -- more VSyncs. |
| -- * 'MISSED_VSYNC_DURING_FAST_SCROLL': Chrome missed one or more VSyncs in |
| -- the middle of a fast regular scroll. |
| -- * 'MISSED_VSYNC_AT_START_OF_FLING': Chrome missed one or more VSyncs |
| -- during the transition from a fast regular scroll to a fling. |
| -- * 'MISSED_VSYNC_DURING_FLING': Chrome missed one or more VSyncs in the |
| -- middle of a fling. |
| jank_reason STRING, |
| -- Number of VSyncs that that Chrome missed (for `jank_reason`) before |
| -- presenting the first scroll update in the frame. Greater than zero. |
| missed_vsyncs LONG |
| ) AS |
| WITH |
| -- Find all 'scroll_jank_v4.missed_vsyncs_per_jank_reason[N]' argument key |
| -- prefixes. |
| key_prefixes_with_indices AS ( |
| SELECT DISTINCT |
| slice.id, |
| arg_set_id, |
| substr(args.key, 1, instr(args.key, ']')) AS key_prefix_with_index |
| FROM slice |
| JOIN args |
| USING (arg_set_id) |
| WHERE |
| slice.name = 'ScrollJankV4' |
| -- "[...]" represents a range in a glob pattern, so we must escape "[" as |
| -- "[[]" and "]" as "[]]". |
| AND args.key GLOB 'scroll_jank_v4.missed_vsyncs_per_jank_reason[[]*[]].*' |
| ) |
| SELECT |
| id, |
| extract_arg(arg_set_id, key_prefix_with_index || '.jank_reason') AS jank_reason, |
| extract_arg(arg_set_id, key_prefix_with_index || '.missed_vsyncs') AS missed_vsyncs |
| FROM key_prefixes_with_indices; |
