Sample After Value

For a custom event-based sampling data collection, set up the Sample After Value (SAV) that is a frequency with which the Intel® VTune™ Amplifier interrupts the processor to collect a sample during hardware event-based data collection. SAV is measured as the number of events it takes to trigger a sample collection.

A Sample After Value that is too small causes the sampling interrupts to occur too frequently, which can lead to performance degradation and system instability. VTune Amplifier enforces a floor value to prevent such a behavior. The recommended value is 1000 samples per second per processor.

VTune Amplifier sets the Sample After value for hardware events automatically. For predefined hardware-level analysis types, the Sample After value is displayed in the Configure Analysis window > HOW pane. You cannot edit the Sample After value provided in the table for each event. But during the data collection the VTune Amplifier may adjust it by a multiplier. The multiplier depends on the sampling interval value specified in the HOW pane.

To edit the default Sample After value, you need to create a custom hardware event-based analysis type (based on an existing type), add events, if required, and edit a Sample After value in the events table by selecting it as follows:

Sample After Value Configuration
For more complete information about compiler optimizations, see our Optimization Notice.
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