In Android GPU Inspector (AGI), you can view and analyze a system profile in the System Profiler UI. After you profile a system and open the trace file in AGI, System Profiler displays the profiling data in a timeline with expandable items that display additional details.
The main elements of the System Profiler UI includes the following:
Timeline: indicates the timespan of trace events.
Track pane: displays profiling data in relation to the timeline.
Details pane: an expandable pane that displays details about a selected item.
In a trace file, the profiling data is stored in timestamped events called trace events. Trace events consist of various types of slices and counters. For example, CPU trace events include scheduling slices, while GPU trace events include GPU performance counters and thread slices.
In the System Profiler UI, the track pane contains trace events that are displayed in rows called tracks, which are based on the timeline. Tracks of the same type are displayed in track groups.
The GPU tracks display GPU profiling information. These are the main GPU track types:
GPU Queue Tracks: GPU activity of the application.
GPU Counter Tracks: GPU's hardware counters sampled at periodic intervals.
Vulkan Events Track: Vulkan API related events.
SurfaceFlinger Tracks: SurfaceFlinger events, which indicate how graphics buffers move through the system.
GPU queue tracks
A GPU can have one or more GPU Queue tracks based on the number of hardware queues that ran during the trace. GPU Queue tracks contain activity slices that represent the period and type of GPU work that was used by your app.
An activity slice contains metadata that you can view, such as the Vulkan command buffer, render pass, and frame buffer that initiated the work. The Vulkan handles to these objects are displayed in the details pane as follows:
You can give user-friendly names to these objects, so you can easily identify
them in a trace alongside their handles, by using the
function from the
VK_EXT_debug_utils extension, or the
function from the
VK_EXT_debug_marker extension. Both extensions are
implemented by AGI and available to your application while tracing.
GPU counter tracks
GPU counter tracks graph the value of GPU performance counters sampled at a periodic interval. The graphs display variations in the performance of your GPUs underlying hardware components between samples. You can use this info to identify bottlenecks in your GPU usage.
The available counters are hardware specific. You can view brief descriptions of each counter by hovering over the track name. For details, see GPU performance counters.
Vulkan event track
The Vulkan event track shows Vulkan API events recorded during the trace. The
track event types are mainly queue submit events (
vkQueueSubmit calls). If you
click a queue submit event, AGI highlights the GPU activity slices that are
associated with the call. You can use this data to inspect the asynchrous work
queued by Vulkan API calls and the latency between the CPU and GPU.
SurfaceFlinger tracks display the lifecycle of graphics buffers (an app's swapchain render targets) as they pogress through the system until they are displayed. The events are aggregated by buffer to make it easier to track the overhead and latency needed for aquiring and posting buffers.
Interact with profiling data
This section describes how to interact with profiling data in the System Profiler UI.
You can pin tracks and track groups by using their pin button.
Collapse and expand
Some tracks and all track groups are are collapsable. Some track groups display a summary when collapsed. For example, when collapsed, the CPU track group shows the overall CPU usage in a graph.
AGI aggregates profiling data based on zoom level. When you first open a trace file, the System Profiler UI displays the entire profile at the maximum zoomed-out level. You can inspect the profile by finding areas of interest and then viewing the details.
As you zoom in and out on different track types, they display different types of profiling data. For example, CPU tracks initially display time slices of each thread, and then eventually swtich to displaying CPU core utilization data when zooming in.
You can display detailed metadata in the details pane by selecting items in the track pane. If an item is selectable, hovering over it will change the cursor to a pointer and then you can choose the item.
Select a time range
You can select a time range, which allows you to compare trace events from different tracks. To do so, enable Timing mode and then drag to select a range. Everything outside of the is dimmed and duration of the range is displayed.
You can also select the time range of a selected slice by pressing
M. You can
then scroll through additional tracks to identify events from the same time
You can navigate items in the track pane with the
WASD keys or by scrolling
and panning. System Profiler uses the same keyboard and mouse
shortcuts as Systrace.
The available shortcuts include the following:
rightarrows pan the view left and right.
downarrows scroll the tracks.
shiftincreases the movement speed of navigation.
Ctrl+scroll zooms on the selected item.
Fzooms on a selected item.
0resets and completely zooms out.
Vtoggles highlighting VSync if it is available in the trace.
Mmarks the current selection by selecting its time range.
?shows the keyboard and mouse shortcut cheatsheet.
The toolbar contains buttons that switch between navigation modes, which
select the action that is performed when you drag items in the track pane. You
can also select the following navigation modes by pressing the
- Selection: Drag to box-select items.
- Pan: Drag to pan and scroll the tracks. This is the default mode.
- Zoom: Drag vertically to zoom on items.
- Timing: Drag to select a time range.
You can also use navigation modes with these modifier keys:
Shift+drag to box select items.
Space+drag to pan and scroll.
Ctrl+scroll to zoom.
Ctrl+drag to select a time range.