Developers of 3D applications understand the importance of convenient tools to analyze frames and rendering performance. Modern 3D applications are extremely complex, and their complexity only grows in time. To use features of various GPUs in the optimal way, programmers need utilities to help them find bugs and bottlenecks in their applications.

A GPU and a CPU perform many different graphics pipeline operations for each frame, and overall performance depends on the slowest segment. That's why convenient debuggers are so important -- it's very difficult to analyze hundreds of calls each millisecond without proper tools.

Utilities for 3D development existed before, of course. For example, Microsoft PIX for Windows from DirectX SDK. Or NVIDIA NVPerfKit or ATI/AMD GPU PerfStudio. Microsoft is interested in PIX not only because of DirectX, but also because of Xbox. And AMD with NVIDIA manufacture GPUs. But there are other manufacturers of graphics solutions, leading ones at that. So, today we are going to review Intel Graphics Performance Analyzer 2.0, which has been announced at GDC 2009.

Graphics Performance Analyzer 2.0

Intel Graphics Performance Analyzer (GPA) 2.0 is a bundle of utilities for 3D developers, which contains powerful tools to analyze performance of Direct3D applications, to detect bottlenecks, and to optimize them. These utilities have a traditional interface for such tools, it resembles Microsoft PIX for Windows or ATI/AMD utilities than tools from NVIDIA, which we already reviewed on our web site.

You can download GPA 2.0 on Intel web site after you register (free of charge) in Visual Adrenalin: http://www.intel.com/software/gpa

GPA 2.0 components:

• System Analyzer is a graphics utility to analyze performance of 3D applications.
• Frame Capture gets frame data.
• Frame Analyzer is an application for detailed frame analysis, debugging, and modification of shaders and DX states in real time.
• Remote Server is a server side of the package that gathers data from metrics and controls a D3D application (together with the video driver).
• SDK provides tools to access features of this package from user applications, including source code samples.

GPA system requirements are stipulated primarily by support (at the initial stage) only for integrated graphics from Intel. As it's still far from the long-expected rollout of discrete products from this company, these utilities currently support only the following chipsets: desktop Intel G45 Express and mobile Intel GM45 Express. That's the main requirement to a test system.

Intel GPA 2.0 system requirements:

• Graphics core made by Intel. There are presently only two integrated solutions: Intel G45 Express and mobile Intel GM45 Express with the latest video driver.
• Microsoft Windows XP (SP2 and higher) or Windows Vista (32-bit and 64-bit versions) with the latest Microsoft DirectX runtime update (in the bundle).
• Microsoft .NET Framework 3.5 (in the bundle).

Let's examine each utility. There is just no point in examining Remote Server -- it looks like a usual console program, even though it's an important part of the package. But its functionality is revealed in client GUI applications.

System Analyzer

This utility allows to analyze performance and find bottlenecks in code. It will also come in handy for other tasks, for example, to determine whether performance is limited by a CPU/GPU or certain GPU units.

Analyzing performance and tweaking 3D applications is always a complex and lengthy process. System Analyzer makes these tasks easier. The graphics interface of this application offers many metrics in a convenient way. You can also use special override modes that disable parts of the 3D render pipeline, so that you can pinpoint potential bottlenecks in an application and main characteristics of the system that affect overall performance (the speed of CPU, texture units, etc).

GPA System Analyzer gathers data from software and hardware metrics using a special instrument video driver. This utility reads the metrics and writes data into a local database, so that they can be displayed for on-the-fly interactive analysis. You can pause an application any time and perform various experiments (read below) without modifying the code. As for now, only Direct3D 9 applications are supported. Other APIs and D3D versions are not supported yet. However, Direct3D 10 and 11 will be added in future.

GPA users can choose several metrics, including D3D, CPU and GPU ones. Here is the list of metrics available in Graphics Performance Analyzer 2.0 (some of them can be disabled in public versions of this program).

CPU:

• Aggregated CPU Utilization -- total load on all CPU cores in a system.
• CPU Breakout Utilization -- bar diagram for all CPUs in a system.
• CPU Multi-line Utilization -- line diagram for all CPU cores.
• CPU Utilization -- usage of a single CPU core: CPU 0, CPU 1, etc.
• Target Application CPU Utilization -- how much a test application loads a CPU (unlike the metrics above that show total CPU usage).

DX (DirectX):

• DX Draw Calls per Frame -- the number of draw calls per frame
• DX VB Locks per Frame -- the number of locks of a vertex buffer
• DX VB Lock Time per Frame -- the amount of time (in microseconds) spent on all VB locks.
• DX VB Lock Percent of Frame Time -- the share of VB lock time in the total frame time (it can exceed 100% in multi-threaded applications).
• DX IB Locks per Frame -- the number of index buffer locks.
• DX IB Lock Time per Frame -- the time spent on IB locks (in milliseconds).
• DX IB Lock Percent of Frame Time -- the share of IB lock time in the total frame time (it can exceed 100% in multi-threaded applications).
• DX Locks per Frame -- the total number of VB and IB locks.
• DX Lock Time per Frame -- the total time spent on VB and IB locks.
• DX Lock Percent of Frame Time -- the share of VB and IB lock time in the total frame time.
• DX State Changes per Frame the number of DX state changes in the last frame.
• Frame Time -- the total frame time in milliseconds.
• Frames per Second -- instant FPS calculated for the current frame.
• Graphics Memory Used -- the amount of graphics memory used (works only in Windows XP).
• Texture Memory Used -- the amount of texture memory used for rendering the current frame (works only in Windows XP).

GPU:

• Clipper Invocation Count -- the number of pixel streams truncated by the clipper (not supported by Intel GS45 Express).
• Driver Time -- the amount of time spent in the video driver in milliseconds (only in Windows XP).
• Driver Time Stalled -- the amount of time the video driver was stalled (Windows XP only).
• Geometry Shader Invocation Count -- the number of geometry shader invocations.
• Pixel Shader Invocation Count -- the number of pixel shader invocations.
• Pixels Rendered -- the number of pixels written into a render target, counted prior to Z test and alpha test.
• Primitive Count -- the number of triangles before the geometry shader.
• System Memory Read Bandwidth -- bandwidth of system memory (MB/s) used for reading data.
• System Memory Write Bandwidth -- system memory bandwidth used for writing data into system memory.
• System Memory Overall Bandwidth -- total memory bandwidth for reading and writing.
• System Memory Multi-line Bandwidth -- line diagram of System Memory Read Bandwidth, System Memory Write Bandwidth, and System Memory Overall Bandwidth metrics.
• Vertex Count -- the number of vertices processed in a frame.
• Vertex Shader Invocation Count -- the number of vertex shader invocations.

System Analyzer activates the following metrics by default: Frames per Second, CPU Utilization, CPU Multi-line Utilization, System Memory Write Bandwidth, System Memory Read Bandwidth, System Memory Overall Bandwidth, System Memory Multi-line Bandwidth.

It's a good choice for most applications, but a user can create and save custom metric sets. You just select a metric in the list, open the context menu, and add the metric to a digram. System Analyzer allows to organize metrics into custom groups and name them to your convenience.

System Analyzer can gather metrics, analyze data, find bottlenecks in 3D applications, and capture frame data for thorough analysis in Frame Analyzer. This utility can be started in two modes: network and local (just like the network mode, but it uses the same system for tests and analysis).

The network mode is naturally the most convenient, that's the recommended mode. There are several reasons for it -- convenience (full-screen applications cannot be analyzed on a single system) and measurement precision. The latter is important, because System Analyzer also uses CPU resources, which may reduce measurement precision, if System Analyzer and a test application run on the same system.

For the network GPA mode, run GPA Remote Server on a test system and System Analyzer on the auxiliary system. The auxiliary system sends a request to the test system to start an application. Then it gathers data from metrics and sends them via network to the auxiliary PC that displays gathered data.

You should specify some parameters in System Analyzer for the network mode: IP address, path to the executable (on the test system), working directory (if a program uses several executable files), and a command line, if necessary. There is also the Force CPU Vertex Processing option. In this case the driver does all vertex processing using a CPU instead of a GPU.

In order to indicate that GPA is running in a given application, a small red rectangle appears in the upper left corner of the screen. If you cannot see it, your program is not a D3D9 application or GPA failed to 'intercept' its calls.

The graphics interface of this program is very convenient, you can configure diagrams to illustrate resource usage by a given 3D application. You can get data from metrics for a specified period of time and scale graphs up and down.

It's possible to export gathered data from diagrams for a more detailed analysis. There is a button in the upper right corner to export all data, you can also export data from one of the diagrams by calling a context menu. Data are exported in popular CSV format, which can be opened in Microsoft Excel, OpenOffice Calc, or other applications.

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