etmem for Tiered Memory Expansion

Introduction

The development of CPU computing power - particularly lower costs of ARM cores - makes memory cost and capacity become the core frustration that restricts business costs and performance. Therefore, the most pressing issue is how to save memory cost and how to expand memory capacity.

etmem is a tiered memory expansion technology that uses DRAM+memory compression/high-performance storage media to form tiered memory storage. Memory data is tiered, and cold data is migrated from memory media to high-performance storage media to release memory space and reduce memory costs. (Currently, non-volatile memory media are not supported.)

Software Architecture

The etmem client interacts with the server through the socket communication mechanism and delivers commands for adding, deleting, starting, stopping, and querying a project. The server reads the project management configuration information and engine configuration information from the configuration file delivered by the client, and performs the operations delivered by the client. After a project is started, the server scans service processes and evicts pages by tier based on the scanning statistics and eviction policy to save memory.

Compilation Tutorial

1. Download the etmem source code.

   # git clone https://gitee.com/src-openeuler/etmem.git
   

2. Install the compilation and running dependency.

   The compilation and running of etmem depend on the libboundscheck component.

   Install the libboundscheck component.

   yum install libboundscheck
   

   Confirm whether it is installed through the rpm package.

   rpm -qa |grep libboundscheck
   

3. Build source code.

   # cd etmem
   # mkdir build
   # cd build
   # cmake ..
   # make
   

Instruction

Starting etmemd

How to Use

Run the etmemd process in binary mode. For example:

# etmemd -l 0 -s etmemd_socket

Printing Help Information

options:
-l|--log-level <log-level>  Log level
-s|--socket <socket name>  Socket name to listen to
-h|--help  Show this message

Command-Line Options

etmem Configuration File

Before running the etmem process, the administrator needs to plan the processes that require memory expansion, configure the process information in the etmem configuration file, and configure the memory scan loops and times, and cold and hot memory thresholds.

The example configuration file is stored in conf/example_conf.yaml of the root directory of the source code in the source package. You are advised to store the example configuration file in the /etc/etmem/ directory. The following is an example:

options:    
 loop : 3
    interval : 1
    sleep: 2
 policies:
  type : pid/name
     value : 123456/mysql
     max_threads: 3
     engine : slide
   param:
    T: 3

Fields in the configuration file are described as follows.

Adding, Deleting, and Querying an etmem Project

Scenario Description

1. The administrator adds an etmem project (a project can contain multiple etmem tasks).

2. The administrator queries an existing etmem project.

3. The administrator deletes an existing etmem project. (Before a project is deleted, all tasks in the project automatically stop.)

How to Use

Add, delete, or query a project using the etmem binary file. Ensure that the server is running properly and the content of the configuration file (for example, /etc/etmem/example_conf.yaml) is correct.

Add a project.

# etmem project add -n test -f /etc/etmem/example_conf.yaml -s etmemd_socket

Delete a project.

# etmem project del -n test -s etmemd_socket

Query a project.

# etmem project show -s etmemd_socket

Print help information.

# etmem project help

Printing Help Information

Usage:
 etmem project add [options]
 etmem project del [options]
 etmem project show
 etmem project help

 Options:
 -f|--file <conf_file> Add configuration file
 -n|--name <proj_name> Add project name
 -s|--sock <sock_name> Socket name to connect

 Notes:
 1. Project name and socket name must be given when execute add or del option.
 2. Configuration file must be given when execute add option.
 3. Socket name must be given when execute show option.

Command-Line Options

Command add

Command del:

Command show:

Starting and Stopping an etmem Project

Scenario Description

After adding a project by running the etmem project add command, the administrator can start or stop the etmem project before running the etmem project del command to delete the project.

1. The administrator starts an added project.

2. The administrator stops a project that has been started.

When the administrator runs the project del command to delete a project, the project automatically stops if it has been started.

How to Use

Start or stop a project using the etmem binary file. Ensure that the server is running properly, the content of the configuration file (for example, /etc/etmem/example_conf.yaml) is correct, and the etmem project has been added.

Start a project.

# etmem migrate start -n test -s etmemd_socket

Stop a project.

# etmem migrate stop -n test -s etmemd_socket

Print help information.

# etmem migrate help

Printing Help Information

Usage:
 etmem migrate start [options]
 etmem migrate stop [options]
 etmem migrate help

 Options:
 -n|--name <proj_name> Add project name
 -s|--sock <sock_name> Socket name to connect

 Notes:
 Project name and socket name must be given when execute start or stop option.

Command-Line Options