-- 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.
-- Find causes for CPUs powering up.
--
-- The scripts below analyse traces with the following tracing options
-- enabled:
--
-- - Linux kernel:
--- "power/*", "sched/*", "task/*",
-- - Chromium:
-- "toplevel", "toplevel.flow".
-- Noteworthy tables:
--
-- chrome_cpu_power_first_toplevel_slice_after_powerup :: The top-level
-- slices that ran after a CPU power-up.
-- The CPU power transitions in the trace.
-- Power states are encoded as non-negative integers, with zero representing
-- full-power operation and positive values representing increasingly deep
-- sleep states.
--
-- On ARM systems, power state 1 represents the WFI (Wait For Interrupt) sleep
-- state that the CPU enters while idle.
CREATE PERFETTO VIEW chrome_cpu_power_slice(
-- The timestamp at the start of the slice.
ts INT,
-- The duration of the slice.
dur INT,
-- The CPU on which the transition occurred
cpu INT,
-- The power state that the CPU was in at time 'ts' for duration 'dur'.
power_state INT,
-- The power state that the CPU was previously in.
previous_power_state INT,
-- A unique ID for the CPU power-up.
powerup_id INT
) AS
WITH cpu_power_states AS (
SELECT
c.id AS id,
cct.cpu AS cpu,
c.ts,
-- Encode the 'value' field as a power state.
CAST((CASE c.value WHEN 4294967295 THEN 0 ELSE c.value + 1 END)
AS INT) AS power_state
FROM counter AS c
JOIN cpu_counter_track AS cct
ON c.track_id = cct.id
WHERE cct.name = 'cpuidle'
)
SELECT *
FROM (
SELECT
ts,
LEAD(ts) OVER (PARTITION BY cpu ORDER BY ts ASC) - ts
AS dur,
cpu,
power_state,
LAG(power_state) OVER (PARTITION BY cpu ORDER BY ts ASC)
AS previous_power_state,
id AS powerup_id
FROM cpu_power_states
)
WHERE dur IS NOT NULL
AND previous_power_state IS NOT NULL
AND power_state = 0 -- Track full-power states.
AND power_state != previous_power_state -- Skip missing spans.
ORDER BY ts ASC;
-- We do not want scheduler slices with utid = 0 (the 'swapper' kernel thread).
CREATE PERFETTO VIEW _cpu_power_valid_sched_slice AS
SELECT *
FROM sched_slice
WHERE utid != 0;
-- Join scheduler slices with the spans with CPU power slices.
--
-- There multiple scheduler slices could fall into one CPU power slice.
--
--- CPU Power:
-- |----------------------------|....................|---------|
-- A <cpu active> B <cpu idling> C D
-- Scheduler slices on that CPU:
-- |-----T1-----| |....T2....| |---T3--|
-- E F G H I J
--
-- Here threads T1 and T2 executed in CPU power slice [A,B]. The
-- time between F and G represents time between threads in the kernel.
CREATE VIRTUAL TABLE _cpu_power_and_sched_slice
USING
SPAN_JOIN(chrome_cpu_power_slice PARTITIONED cpu,
_cpu_power_valid_sched_slice PARTITIONED cpu);
-- The Linux scheduler slices that executed immediately after a
-- CPU power up.
CREATE PERFETTO TABLE chrome_cpu_power_first_sched_slice_after_powerup(
-- The timestamp at the start of the slice.
ts INT,
-- The duration of the slice.
dur INT,
-- The cpu on which the slice executed.
cpu INT,
-- Id for the sched_slice table.
sched_id INT,
-- Unique id for the thread that ran within the slice.
utid INT,
-- The CPU's power state before this slice.
previous_power_state INT,
-- A unique ID for the CPU power-up.
powerup_id INT
) AS
SELECT
ts,
dur,
cpu,
id AS sched_id,
utid,
previous_power_state,
powerup_id
FROM _cpu_power_and_sched_slice
WHERE power_state = 0 -- Power-ups only.
GROUP BY cpu, powerup_id
HAVING ts = MIN(ts) -- There will only be one MIN sched slice
-- per CPU power up.
ORDER BY ts ASC;
-- A view joining thread tracks and top-level slices.
--
-- This view is intended to be intersected by time with the scheduler
-- slices scheduled after a CPU power up.
--
-- utid Thread unique id.
-- slice_id The slice_id for the top-level slice.
-- ts Starting timestamp for the slice.
-- dur The duration for the slice.
CREATE PERFETTO VIEW _cpu_power_thread_and_toplevel_slice AS
SELECT
t.utid AS utid,
s.id AS slice_id,
s.ts,
s.dur
FROM slice AS s
JOIN thread_track AS t
ON s.track_id = t.id
WHERE s.depth = 0 -- Top-level slices only.
ORDER BY ts ASC;
-- A table holding the slices that executed within the scheduler
-- slice that ran on a CPU immediately after power-up.
--
-- @column ts Timestamp of the resulting slice
-- @column dur Duration of the slice.
-- @column cpu The CPU the sched slice ran on.
-- @column utid Unique thread id for the slice.
-- @column sched_id 'id' field from the sched_slice table.
-- @column type From the sched_slice table, always 'sched_slice'.
-- @column end_state The ending state for the sched_slice
-- @column priority The kernel thread priority
-- @column slice_id Id of the top-level slice for this (sched) slice.
CREATE VIRTUAL TABLE chrome_cpu_power_post_powerup_slice
USING
SPAN_JOIN(chrome_cpu_power_first_sched_slice_after_powerup PARTITIONED utid,
_cpu_power_thread_and_toplevel_slice PARTITIONED utid);
-- The first top-level slice that ran after a CPU power-up.
CREATE PERFETTO VIEW chrome_cpu_power_first_toplevel_slice_after_powerup(
-- ID of the slice in the slice table.
slice_id INT,
-- The power state of the CPU prior to power-up.
previous_power_state INT
) AS
SELECT slice_id, previous_power_state
FROM chrome_cpu_power_post_powerup_slice
GROUP BY cpu, powerup_id
HAVING ts = MIN(ts)
ORDER BY ts ASC;
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