Intel® VTune™ Profiler User Guide

User Guide

Contents

io
 Command Line Analysis

Syntax

vtune
 -collect io [-knob <
knobName
=
knobValue
>] [--
target
] [
target_options
]

Knobs

Knob
Allowed Values
Default Value
Description
collect-pcie-bandwidth
true/false
true
Collect data for:
  • Inbound bandwidth (Intel® Data Direct I/O)
  • Outbound bandwidth (Memory-Mapped I/O)
  • L3 misses
  • Average latencies of inbound I/O requests
mmio
true/false
false
Collect the data required to locate code that induces outbound I/O traffic by accessing devices through MMIO space.
iommu
true/false
false
Collect the data required to calculate performance metrics for Intel® Virtualization Technology for Directed I/O (Intel VT-d).
collect-memory-bandwidth
true/false
true
Collect the data required to compute memory, persistent memory and cross-socket bandwidth.
dram-bandwidth-limits
true/false
true
Evaluate maximum achievable local DRAM bandwidth before the collection starts. This data is used to scale bandwidth metrics on the timeline and calculate thresholds.
OS- and API-level Metric Knobs:
Knob
Allowed Values
Default Value
Description
dpdk
true/false
false
Collect DPDK metrics. Make sure DPDK is built with
VTune
Profiler
 support.
spdk
true/false
false
Collect SPDK metrics. Make sure SPDK is built with
VTune
Profiler
 support.
kernel-stack
true/false
false

Prerequisites

Linux* OS:
See the Input and Output analysis User Guide for detailed prerequisites for each metric type.
FreeBSD* OS:
Install the FreeBSD target package and configure your system following the instructions.
Examples
Example 1: Input and Output Analysis — Launch a Target Application
Run the Input and Output analysis with Intel® VT-d metrics collection enabled for the target application
<app>
: 
vtune -collect io -knob iommu=true -- <app>
Example 2: Input and Output Analysis – Attach to Target Application
Run the Input and Output analysis with Intel VT-d and SPDK metrics collection and without MMIO access feature in the Attach to Process mode.
Attach by
process name
: 
vtune -collect io -knob iommu=true -knob mmio=false -knob spdk=true --target-process=<process_name>
Or attach by
PID
: 
vtune -collect io -knob iommu=true -knob mmio=false -knob spdk=true --target-pid=<pid>
Example 3: Input and Output Analysis - Profile System
Run a system-wide Input and Output analysis without specific target application for 30 seconds: 
vtune -collect io --duration 30

What's Next

When the data collection is complete, do one of the following to view the result:

Product and Performance Information

1

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