Intel® Advisor User Guide

User Guide

Contents

CPU Roofline Report Overview

Review the controls available in the main report of the
CPU / Memory Roofline Insights
 perspective of the
Intel® Advisor
.

Basic Roofline Chart (Low Accuracy)

There are several controls to help you focus on the
Roofline
 chart data most important to you, including the following.
Intel Advisor Cache-Aware Roofline Chart
1
  • Select Loops by Mouse Rect
    : Select one or more loops/functions by tracing a rectangle with your mouse.
  • Zoom by Mouse Rect
    : Zoom in and out by tracing a rectangle with your mouse. You can also zoom in and out using your mouse wheel.
  • Move View By Mouse
    : Move the chart left, right, up, and down.
  • Undo
     or
    Redo
    : Undo or redo the previous zoom action.
  • Cancel Zoom
    : Reset to the default zoom level.
  • Export as x
    : Export the chart as a dynamic and interactive HTML or SVG file that does not require the
    Intel Advisor
     viewer for display. Use the arrow to toggle between the options.
2
Use the
Cores
 drop-down toolbar to:
  • Adjust rooflines to see practical performance limits for your code on the host system.
  • Build roofs for single-threaded applications (or for multi-threaded applications configured to run single threaded, such as one thread-per-rank for MPI applications. (You can use Intel Advisor filters to control the loops displayed in the
    Roofline
     chart; however, the
    Roofline
     chart does not support the
    Threads
     filter.)
Choose the appropriate number of CPU cores to scale roof values up or down:
  • 1 – if your code is single-threaded
  • Number of cores equal or close to the number of threads – if your code has fewer threads than available CPU cores
  • Maximum number of cores – if your code has more threads than available CPU cores
By default, the number of cores is set to the number of threads used by the application (even values only).
You’ll see the following options if your code is running on a multisocket PC:
  • Choose
    Bind cores to 1 socket
     (default) if your application binds memory to one socket. For example, choose this option for MPI applications structured as one rank per socket.
    This option may be disabled if you choose a number of CPU cores exceeding the maximum number of cores available on one socket.
  • Choose
    Spread cores between all n sockets
     if your application binds memory to all sockets. For example, choose this option for non-MPI applications.
3
  • Toggle the display between floating-point (FLOP), integer (INT) operations, and mixed operations (floating-point and integer).
  • If you collected Roofline with Calltacks:
     Enable the display of Roofline with Callstacks additions to the
    Roofline
     chart.
4
Display
Roofline
 chart data from other
Intel Advisor
 results or non-archived snapshots for comparison purposes.
Use the drop-down toolbar to:
  • Load a result/snapshot and display the corresponding filename in the
    Compared Results
     region.
  • Clear a selected result/snapshot and move the corresponding filename to the
    Ready for comparison
     region.
    Note
    : Click a filename in the
    Ready for comparison
     region to reload the result/snapshot.
  • Save the comparison itself to a file.
    The arrowed lines showing the relationship among loops/functions do not reappear if you upload the comparison file.
Click a loop/function dot in the current result to show the relationship (arrowed lines) between it and the corresponding loop/function dots in loaded results/snapshots.
Intel Advisor: Roofline Comparison
5
Add visual indicators to the Roofline chart to make the interpretation of data easier, including performance limits and whether loops/functions are memory bound, compute bound, or both.
Use the drop-down toolbar to:
  • Show a vertical line from a loop/function to the nearest and topmost performance ceilings by enabling the
    Display roof rulers
     checkbox. To view the ruler, hover the cursor over a loop/function. Where the line intersects with each roof, labels display hardware performance limits for the loop/function.
  • If you collected Roofline for All Memory Levels
    : Visually emphasize the relationships among displayed memory levels and roofs and for a selected loop/function dot by enabling the
    Show memory level relationships
     checkbox.
  • Color the roofline zones to make it easier to see if enclosed loops/functions are fundamentally memory bound, compute bound, or bound by compute and memory roofs by enabling the
    Show Roofline boundaries
     checkbox.
The preview picture is updated as you select guidance options, allowing you to see how changes will affect the Roofline chart’s appearance. Click
Apply
 to apply your changes, or
Default
 to return the Roofline chart to its original appearance.
Once you have a loop/function's dots highlighted, you can zoom and fit the Roofline chart to the dots for the selected loop/function by once again double-clicking the loop/function or pressing
SPACE
 or
ENTER
 with the loop/function selected. Repeat this action to return to the original Roofline chart view.
To hide the labeled dots, select another loop/function, or double-click an empty space in the Roofline chart.
6
  • Roofline View Settings:
    Adjust the default scale setting to show:
    • The optimal scale for each
      Roofline
       chart view
    • A scale that accommodates all
      Roofline
       chart views
  • Roofs Settings:
    Change the visibility and appearance of roofline representations (lines):
    • Enable calculating roof values based on single-threaded benchmark results instead of multi-threaded.
    • Click a
      Visible
       checkbox to show/hide a roofline.
    • Click a
      Selected
       checkbox to change roofline appearance: display a roofline as a solid or a dashed line.
    • Manually fine-tune roof values in the
      Value
       column to set hardware limits specific to your code.
  • Loop Weight Representation
    : Change the appearance of loop/function weight representations (dots):
    • Point Weight Calculation
      : Change the
      Base Value
       for a loop/function weight calculation.
    • Point Weight Ranges
      : Change the
      Size
      ,
      Color
      , and weight
      Range (R)
       of a loop/function dot. Click the
      +
       button to split a loop weight range in two. Click the
      -
       button to merge a loop weight range with the range below.
    • Point Colorization
      : color loop/function dots by weight ranges or by type (vectorized or scalar). You can also change the color of loop with no self time.
You can save your Roofs Settings or Point Weight Representation configuration to a JSON file or load a custom configuration.
7
Zoom in and out using numerical values.
8
Click a loop/function dot to:
  • Outline it in black.
  • Display metrics for it.
  • Display corresponding data in other window tabs.
Right-click a loop/function dot or a blank area in the
Roofline
 chart to perform more functions, such as:
  • Further simplify the
    Roofline
     chart by filtering out (temporarily hiding a dot), filtering in (temporarily hiding all other dots), and clearing filters (showing all originally displayed dots).
  • Copy data to the clipboard.
9
Show/hide the metrics pane:
  • Review the basic performance metrics in the
    Point Info
     pane.
  • If you collected the Roofline for All Memory Levels
    : Review how efficiently the loop/function uses cache and what memory level bounds the loop/function in the
    Memory Metrics
     pane.
10
Display the number and percentage of loops in each loop weight representation category.

Roofline with Callstacks Chart (Medium Accuracy)

Intel Advisor Roofline with Callstacks
1
Enable the display of Roofline with Callstacks additions to the Roofline chart.
2
Show/hide loop/function descendants:
  • Click a loop/function dot Intel Advisor: Collapse control control to collapse descendant dots into the parent dot.
  • Click a loop/function dot Intel Advisor: Expand control control to show descendant dots and their relationship via visual indicators to the parent dot.
You can also right-click a loop/function dot to open the context menu and expand/collapse the loop/function subtree.
3
Show/hide the
Callstack
 and other panes.
4
  • Click an item in the
    Callstack
     pane to flash the corresponding loop/function dot in the Roofline chart.
  • Right-click an item in the
    Callstack
     pane to open the context menu and expand/collapse the item subtree.
You can also click an item in the
Callstack
 pane to flash the corresponding loop/function dot in the
Roofline
 chart.

Memory-Level Roofline Chart (Medium Accuracy)

Intel Advisor Memory-Level Roofline Chart
1
Visually emphasize the relationships among displayed memory levels and roofs for a selected loop/function dot by enabling the
Show memory level relationships
 checkbox.
This checkbox is enabled by default.
2
Use the drop-down toolbar to:
  • Select the
    Memory Level
    (s) to show for each loop/function in the chart (L1, L2, L3, DRAM).
  • Select which
    Memory Operation Types
    (s) to display data for in the Roofline chart:
    Loads
    ,
    Stores
    , or
    Loads and Stores
    .
3
Double-click a dot or select a dot and press
SPACE
 or
ENTER
 to examine how the relationships between displayed memory levels and roofs:
  • Labeled dots are displayed, representing memory levels for the selected loop/function. Lines connect the dots to indicate that they correspond to the selected loop/function.
    If you have chosen to display only some memory levels in the chart using the
    Memory Level
     option, unselected memory levels are displayed with X marks.
  • An arrowed line is displayed, pointing to the memory level roofline that bounds the selected loop. If the arrowed line cannot be displayed, a message will pop up with instructions on how to fix it.
4
Show/hide the
Memory Metrics
 and other panes.
In the
Memory Metrics
 pane:
  • Review the time spent processing requests for each memory level reported in the
    Impacts
     histogram. A big value indicates a memory level that bounds the selected loop.
  • Review an amount of data that passes through each memory level reported in the
    Shares
     histogram.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.