How It Works

Loads
and
Stores
metrics that show the total number of loads and stores
LLC Miss Count
metric that shows the total number of last-level cache misses
Local DRAM Access Count
metric that shows the total number of LLC misses serviced by the local memory
Remote DRAM Access Count
metric that shows the number of accesses to the remote socket memory
Remote Cache Access Count
metric that shows the number of accesses to the remote socket cache
Memory Bound
metric that shows a fraction of cycles spent waiting due to demand load or store instructions
L1 Bound
metric that shows how often the machine was stalled without missing the L1 data cache
L2 Bound
metric that shows how often the machine was stalled on L2 cache
L3 Bound
metric that shows how often the CPU was stalled on L3 cache, or contended with a sibling core
L3 Latency
metric that shows a fraction of cycles with demand load accesses that hit the L3 cache under unloaded scenarios (possibly L3 latency limited)
NUMA: % of Remote Accesses
metric shows percentage of memory requests to remote DRAM. The lower its value is, the better.
DRAM Bound
metric that shows how often the CPU was stalled on the main memory (DRAM). This metric enables you to identify
DRAM Bandwidth Bound
,
UPI Utilization Bound
issues, as well as
Memory Latency
issues with the following metrics:
Remote / Local DRAM Ratio
metric that is defined by the ratio of remote DRAM loads to local DRAM loads
Local DRAM
metric that shows how often the CPU was stalled on loads from the local memory
Remote DRAM
metric that shows how often the CPU was stalled on loads from the remote memory
Remote Cache
metric that shows how often the CPU was stalled on loads from the remote cache in other sockets
Average Latency
metric that shows an average load latency in cycles

Configure and Run Analysis

Click the (standalone GUI)/ (Visual Studio IDE)
Configure Analysis
button on the
Intel® VTune™
Profiler
toolbar.
The
Configure Analysis
window opens.
From
HOW
pane, click the Browse button and select
Memory Access
.
Configure the following options:
CPU sampling interval, ms field	Specify an interval (in milliseconds) between CPU samples. Possible values - 0.01-1000 . The default value is 1 ms .
Analyze dynamic memory objects check box (Linux only)	Enable the instrumentation of dynamic memory allocation/de-allocation and map hardware events to such memory objects. This option may cause additional runtime overhead due to the instrumentation of all system memory allocation/de-allocation API. The option is disabled by default.
Minimal dynamic memory object size to track, in bytes spin box (Linux only)	Specify a minimal size of dynamic memory allocations to analyze. This option helps reduce runtime overhead of the instrumentation. The default value is 1024 .
Evaluate max DRAM bandwidth check box	Evaluate maximum achievable local DRAM bandwidth before the collection starts. This data is used to scale bandwidth metrics on the timeline and calculate thresholds. The option is enabled by default.
Analyze OpenMP regions check box	Instrument and analyze OpenMP regions to detect inefficiencies such as imbalance, lock contention, or overhead on performing scheduling, reduction and atomic operations. The option is disabled by default.
Details button	Expand/collapse a section listing the default non-editable settings used for this analysis type. If you want to modify or enable additional settings for the analysis, you need to create a custom configuration by copying an existing predefined configuration. VTune Profiler creates an editable copy of this analysis type configuration.
Click the Start button to run the analysis.

Memory objects analysis can be configured for Linux* targets only and only for processors based on Intel microarchitecture code name Sandy Bridge or later.

View Data

Summary
window displays statistics on the overall application execution, including the application-level bandwidth utilization histogram.
Bottom-up
window displays performance data per metric for each hotspot object. If you enable the
Analyze memory objects
option for data collection, the
Bottom-up
window also displays memory allocation call stacks in the grid and Call Stack pane. Use the
Memory Object
grouping level, preceded with the
Function
level, to view memory objects as the source location of an allocation call.
Platform
window provides details on tasks specified in your code with the Task API, Ftrace*/Systrace* event tasks, OpenCL™ API tasks, and so on. If corresponding platform metrics are collected, the Platform window displays over-time data as GPU usage on a software queue, CPU time usage, OpenCL™ kernels data, and GPU performance per the Overview group of GPU hardware metrics, Memory Bandwidth, and CPU Frequency.

Support Limitations

2nd Generation Intel® Core™ processors
Intel® Xeon® processor families, or later
3rd Generation Intel Atom® processor family, or later