Visible to Intel only — GUID: GUID-26D364BB-BEB2-4988-80AC-4E5FFA924068
Visible to Intel only — GUID: GUID-26D364BB-BEB2-4988-80AC-4E5FFA924068
io Command Line Analysis
Syntax
vtune -collect io [-knob <knobName=knobValue>] [-- target] [target_options]
Knobs
Platform-Level Metric Knobs:
Knob | Allowed Values | Default Value | Description |
---|---|---|---|
collect-pcie-bandwidth | true/false | true | Collect data for:
|
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 | Profile Linux kernel I/O stack. |
Prerequisites
Linux* OS:
Load the sampling driver or use driverless hardware event collection (Linux).
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:
Use the -report action to view the data from command line.
Use the -report-output action to write report to a .txt or .csv file
Open the data collection result (*.vtune) in the VTune Profiler graphical interface.