System Overview Analysis
Hardware Event-Based Sampling Mode
- Atrace* events: input, view, webview, audio, video, camera, hal, res, dalvik
- Ftrace events: sched, freq, idle, workq, filesystem, irq, softirq, sync, disk
Hardware Tracing Mode (Linux and Android Targets)
- To enable system-level analysis for this mode, consider setting the/proc/sys/kernel/perf_event_paranoidvalue to 0 or less.
- To see the kernel module and its symbols, set/proc/sys/kernel/kptr_restrictto 0.
- Make sure there is a disk space on both target and host systems. Depending on the number of CPU cores, the amount of collected data may reach 1GB per second.
- Make sure your kernel version is 4.3 or higher.
- Analyze user/kernel mode transitions and interrupts
- Explore execution of unexpected processes or system services
- Measure particular stages of workload execution without static instrumentation
- Analyze CPU core activities at the microsecond level
- Analyze a kernel/driver or application module by measuring exact CPU time with a nanosecond precision
- Triage latency issues resulted from:
- changes in the execution code flow
- preemption by another process
- resource sharing issues
- page faults
- power consumption issues caused by unexpected wake-ups
- This analysis requires a direct access to the hardware. It does not work inside a Guest VM.
- In most cases, the collection overhead in this mode is less than 10%. It can be higher if your application is IO or DRAM bound.
- The Hardware Tracing mode does not require sampling drivers.
Configure and Run Analysis
- Click theConfigure Analysisbutton onIntel® VTune™toolbar.ProfilerTheConfigure Analysiswindow opens.
- FromHOWpane, click the Browse button and selectSystem Overview.
- SelectHardware TracingorHardware Event-Based Samplingmode.For theHardware Tracingmode, you can also enable theAnalyze interruptsoption.With the defaultHardware Tracingconfiguration,Intel® VTune™stops the data collection when a 1GB data limit is reached. You can change this limit in theProfilerAdvancedsection of theWHATpane:
- Click the Start button to run the analysis.