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-- Copyright 2023 The Chromium Authors
-- Use of this source code is governed by a BSD-style license that can be
-- found in the LICENSE file.
INCLUDE PERFETTO MODULE chrome.event_latency_description;
-- Source of truth of the descriptions of EventLatency-based scroll jank causes.
CREATE PERFETTO TABLE chrome_scroll_jank_cause_descriptions (
-- The name of the EventLatency stage.
event_latency_stage STRING,
-- The process where the cause of scroll jank occurred.
cause_process STRING,
-- The thread where the cause of scroll jank occurred.
cause_thread STRING,
-- A description of the cause of scroll jank.
cause_description STRING
) AS
WITH
cause_descriptions(event_latency_stage, cause_process, cause_thread, cause_description) AS (
SELECT
*
FROM (VALUES
(
'GenerationToBrowserMain',
'Browser',
'CrBrowserMain',
'This also corresponds to a matching InputLatency::TouchMove. Key ' || 'things to look for: Browser Main thread (CrBrowserMain) is busy, often ' || 'running tasks. The true cause can be confirmed by checking which tasks ' || 'are being run on CrBrowserMain, or checking any ScopedBlockingCall ' || 'slices during this stage from a ThreadPoolForegroundWorker, or ' || 'checking if the NetworkService is busy. Common causes may include page' || 'navigations (same document and new pages), slow BeginMainFrames, and ' || 'Java Choreographer slowdowns.'
),
(
'RendererCompositorQueueingDelay',
'Renderer',
'Compositor',
'The renderer needs to decide to produce a frame in response to a ' || 'BeginFrame signal. Sometimes it can not because it is waiting on the ' || 'RendererMain thread to do touch targeting or javascript handling or ' || 'other such things causing a long queuing delay after it has already ' || 'started the scroll (so the TouchStart has been processed).'
),
(
'RendererCompositorQueueingDelay',
'GPU',
'VizCompositorThread',
'Waiting for a BeginFrame to be sent. Key things to look for: check if ' || 'a fling occurred before or during the scroll; flings produce a single ' || 'input and result in multiple inputs coalescing into a single frame.'
),
(
'ReceiveCompositorFrameToStartDraw',
'GPU',
'VizCompositorThread',
'A delay when the VizCompositor is waiting for the frame, but may be ' || 'connected to other processes and threads. Key things to look for: ' || 'check the BeginFrame task that finished during this EventLatency. The ' || 'VizCompositor holds onto the frame/does not send it on. Alternately ' || 'the system may be holding on to the buffer.'
),
(
'ReceiveCompositorFrameToStartDraw',
'GPU',
'CrGpuMain',
'Key things to look for: if the GPU Main thread is busy, and does not ' || 'release the buffer; specific causes will be on the GPU Main thread. If ' || 'this thread is not busy, the buffer may be held by the system instead.'
),
(
'ReceiveCompositorFrameToStartDraw',
'Browser',
'CrBrowserMain',
'Key things to look for: the toolbar on the Browser may be blocked by ' || 'other tasks.'
),
(
'BufferReadyToLatch',
'GPU',
'VizCompositorThread',
'Often a scheduling issue. The frame was submitted, but missed the ' || 'latch in the system that was received from the previous frame. The ' || 'system only latches a buffer once per frame; when the latch deadline ' || 'is missed, the system is forced to wait for another vsync interval to ' || 'latch again. Key things to look for: whether the event duration before ' || 'BufferReadyToLatch stage of the previous EventLatency is longer or ' || 'shorter than the event duration before BufferReadyToLatch in the ' || 'current EventLatency. If this duration is longer, then this is a ' || 'System problem. If this duration is shorter, then it is a Chrome ' || 'problem. The previous frame may have been drawn too quickly, or the ' || 'GPU may be delayed.'
),
(
'SwapEndToPresentationCompositorFrame',
'GPU',
'VizCompositorThread',
'May be attributed to a scheduling issue as with BufferReadyToLatch. ' || 'The frame was submitted, but missed the latch in the system that was ' || 'received from the previous frame. The system only latches a buffer ' || 'once per frame; when the latch deadline is missed, the system is ' || 'forced to wait for another vsync interval to latch again. Key things ' || 'to look for: whether the event duration before BufferReadyToLatch ' || 'stage of the previous EventLatency is longer or shorter than the event ' || 'duration before BufferReadyToLatch in the current EventLatency. If ' || 'this duration is longer, then this is a System problem. If this ' || 'duration is shorter, then it is a Chrome problem. The previous frame ' || 'may have been drawn too quickly, or the GPU may be delayed.'
),
(
'SwapEndToPresentationCompositorFrame',
'GPU',
'CrGpuMain',
'Key things to look for: whether StartDrawToBufferAvailable is also ' || 'present during this EventLatency. If so, then the GPU main thread may ' || 'be descheduled or busy. If surfaceflinger is available, check there as ' || 'well.'
),
(
'SwapEndToPresentationCompositorFrame',
'GPU',
'surfaceflinger',
'Key things to look for: whether StartDrawToBufferAvailable is also ' || 'present during this EventLatency. If so, then the VizCompositor has ' || 'not received a signal from surfaceflinger to start writing into the ' || 'buffer.'
)) AS _values
)
SELECT
event_latency_stage,
cause_process,
cause_thread,
cause_description
FROM cause_descriptions;
-- Combined description of scroll jank cause and associated event latency stage.
CREATE PERFETTO VIEW chrome_scroll_jank_causes_with_event_latencies (
-- The name of the EventLatency stage.
name STRING,
-- Description of the EventLatency stage.
description STRING,
-- The process name that may cause scroll jank.
cause_process STRING,
-- The thread name that may cause scroll jank. The thread will be on the
-- cause_process.
cause_thread STRING,
-- Description of the cause of scroll jank on this process and thread.
cause_description STRING
) AS
SELECT
stages.name,
stages.description,
causes.cause_process,
causes.cause_thread,
causes.cause_description
FROM chrome_event_latency_stage_descriptions AS stages
LEFT JOIN chrome_scroll_jank_cause_descriptions AS causes
ON causes.event_latency_stage = stages.name;
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