Linux Tactic

Maximizing Performance with Numastat: Insights into NUMA Memory Usage

Introduction to Numastat

If you’ve ever worked with Non-uniform memory access (NUMA) systems, you might have found it challenging to understand how the memory is distributed among the different nodes. This is where Numastat comes in it’s a powerful tool that provides insights into the memory usage of your NUMA system.

Installation of Numastat

To get started, you need to ensure that Numastat is installed on your system. On Linux, you can use a package manager to install it, or you can download the source code and build it manually.

Once Numastat is installed, you can run it from the terminal.

Overview of Numastat Output

Numastat provides a lot of information, but don’t let that overwhelm you. Here’s what you need to understand:

– numa_hit: the number of memory accesses that hit the local node

– numa_miss: the number of memory accesses that missed the local node

– numa_foreign: the number of memory accesses that hit a remote node

– interleave_hit: the number of memory accesses that hit interleaved memory

– local_node: the amount of memory allocated on the local node

– other_node: the amount of memory allocated on remote nodes

As you can see, Numastat provides a detailed breakdown of how memory is being used on your system, allowing you to optimize your memory usage.

Functionality of Numastat Options

Numastat provides a range of options that can help you get the most out of the tool. Here are some of the most useful ones:

1.

Use of “-c” option to shrink column width

If you’re working with a smaller terminal window, the default column width of Numastat might be too wide. You can use the “-c” option to shrink the column width, making it easier to read.

For example, you can use the following command:

numastat -c 10

This will limit each column to 10 characters. 2.

Use of “-n” option to show original numastat statistics

By default, Numastat displays memory usage in megabytes. However, if you prefer the original formatting, you can use the “-n” option.

For example:

numastat -n

This will show the original format of Numastat statistics. 3.

Use of “-s” option to display data from higher to lower values

If you want to sort the memory usage data from highest to lowest, you can use the “-s” option. For example:

numastat -s

This will display the memory usage data from highest to lowest. 4.

Use of “-m” option to display memory usage data in meminfo-like format

If you’re familiar with the /proc/meminfo file, you might find it easier to understand memory usage data in that format. You can use the “-m” option to display memory usage data in a meminfo-like format.

For example:

numastat -m

This will display memory usage data in a meminfo-like format. 5.

Use of “-z” option to show only non-zero values

If you want to filter out columns and rows that have zero values, you can use the “-z” option. For example:

numastat -z

This will show only non-zero values in the Numastat output. 6.

Use of “-p” option to show per-node memory allocation of a specific PID

If you want to see how memory is allocated on each node for a specific process, you can use the “-p” option. For example:

numastat -p 1234

This will show the per-node memory allocation for process ID 1234. 7.

Use of “-v” option to display verbose output

If you want more detailed output, you can use the “-v” option. For example:

numastat -v

This will display more verbose output. 8.

Use of “watch” command to continuously monitor changing memory node values

If you want to continuously monitor changing memory node values, you can use the “watch” command. For example:

watch -n 1 numastat

This will display the Numastat output every second, allowing you to monitor changes in memory node values. 9.

Use of “–help” option to display help information

If you need help with the Numastat tool, you can use the “–help” option. For example:

numastat –help

This will display help information for Numastat. 10.

Use of “-V” option to display version of Numastat tool

If you want to know which version of Numastat you’re using, you can use the “-V” option. For example:

numastat -V

This will display the version of Numastat that you’re using.

Final Thoughts

Numastat is a powerful tool that can help you understand how memory is being used on your NUMA system. With its range of options, you can customize the output to suit your needs.

Whether you’re troubleshooting performance issues or simply trying to optimize your memory usage, Numastat is an indispensable tool for any system administrator working with NUMA systems.

Summary of Numastat and Its Purpose

Numastat is a versatile tool designed for Non-uniform memory access (NUMA) systems. It provides detailed statistics about memory usage on each node, helping administrators optimize their memory usage.

Numastat produces four primary output columns: numa_hit, numa_miss, numa_foreign, and interleave_hit. Each column provides essential data about the memory usage, including how often the processor accesses memory on the local (NUMA) node, missed the node, accessed memory on a remote node, or accessed interleaved memory.

Different Memory Policies for Each NUMA

NUMA systems are designed to offer better performance by dividing and allocating memory across different nodes for accessing the processor(s). By default, the NUMA system distributes the memory symmetrically across all nodes.

However, there are different memory policies used to manage memory allocation on each node. The two major policies used in NUMA systems are the First Touch policy (FT) and the Interleave policy (IT).

FT policy is a memory allocation policy that assigns the first-touch of memory to the node that first accesses it. This policy divides the “process pages” between the different nodes, depending on where they are accessed first.

Once the memory allocation is done, the system remains in a permanent state, without any memory migration. IT policy is a memory allocation policy that divides the memory symmetrically, assigning a memory block to every node on the system alternately.

This policy attempts to distribute memory in a more uniform way.

Limitations of Numastat in Displaying Output

Numastat is a powerful tool that provides detailed statistics about memory usage on each node. However, like every other tool, Numastat has its limitations.

One of the significant limitations of Numastat is related to terminal width. The output format has default column widths, which might make it challenging to read if you’re using a smaller terminal window.

You can use the “-c” option to reduce the column width to fit within your terminal window. In addition to the terminal width, the output format might be difficult to read due to the large number of nodes in NUMA systems.

For example, if you have a system with 16 nodes, the output would have 16 rows for each output column. This scenario makes it challenging to get a quick overview of the memory usage data.

However, you can use the “-s” option to sort the memory usage data from highest to lowest or use the “-z” option to show only non-zero memory allocation values. Another limitation of Numastat is its inability to provide a more visual representation of memory node usage by opening itself to GUI-based development needs.

A Graphical User Interface (GUI) is more intuitive and easy to understand, making it easier to identify memory processing bottlenecks.

Conclusion

Numastat is an essential tool for any system administrator working with NUMA systems. With its various options, the tool can be customized to suit individual needs.

Numastat provides insight into how memory is being used on each node, allowing administrators the opportunity to optimize memory usage. Lastly, while Numastat has its limitations, its utility is not diminished, as it enhances system administrators’ efforts to better allocate processing memory across the system.

In conclusion, Numastat is a crucial tool for administrators working with NUMA systems. It provides memory statistics for each node, allowing for the optimization of memory usage.

The tool offers several options to customize output and understand data at a more granular level. While Numastat has its limitations, such as the default terminal width, these limitations do not diminish its utility.

It provides essential information that makes it easier to identify system performance bottlenecks and optimize memory usage. Ultimately, Numastat’s importance lies in improving a system’s efficiency by intelligently allocating processing memory across the system, contributing to quicker processing speeds, and outputting high-quality results.

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