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Linux Monitoring

The Linux monitoring module allows NeoLoad to retrieve system information from Linux platforms during the test, connecting to your servers using either the Telnet or SSH protocol.

The Linux module has been validated on Fedora, Mandriva, Suse and Debian.

Features

Preconfigured Monitoring: Each module ships pre-configured with the performance counters tailored to your system.
Threshold Alerts: NeoLoad provides threshold values –derived from industry best practices- to raise the appropriate alerts.
Agentless Monitoring: The design of our monitoring modules, based on industry standards, ensures non-intrusive remote monitoring.
Real Time: The counter values and the threshold alerts are available as soon as the test is run.

Note: All the modules are included with the demo license.

Performance Counters

NeoLoad opens a session on the server, and uses system commands to retrieve the performance counters.

The available counters are divided into 4 categories:

System

CPU User : Time spent running non-kernel code (user time, including nice time). Percentage of total CPU time.
CPU System : Time spent running kernel code (system time). Percentage of total CPU time.
CPU Idle : Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time. Percentage of total CPU time.
Interruptions Count : Number of interrupts per second, including the clock.
Context Switch Count : Number of context switches per second.
Processes Runnable : Number of processes waiting for run time.
Processes Sleeping : Number of processes in uninterruptible sleep.
Processes Swapped : Number of processes swapped out but otherwise runnable. This field is calculated; however, Linux never desperation swaps.
Warning:This field is not accessible on all Linux operating systems (w field in the procs section of the vmstat command).

Memory

Total Memory: Total usable RAM (i.e. physical RAM minus a few reserved bits and the kernel binary code).
Memory Used: Total memory - Memory free.
Memory Free: The sum of LowFree+HighFree (overall stat).
Memory Buffered: Memory in buffer cache. Mostly useless as metric nowadays.
Memory Cache: Memory in the PageCache (DiskCache) minus SwapCache.
Total Swap: Total amount of physical swap memory.
Swap Free: Total amount of swap memory free.
Swap Used: Total Swap - Swap Free.

Disk. Monitors for the disk section are available per peripheral device.

Disk Read Request Merged: The number of read requests merged per second issued to the device.
Disk Write Request Merged : The number of write requests merged per second issued to the device.
Disk Read: The number of read requests issued to the device per second.
Disk Write: The number of write requests issued to the device per second.
Disk Read (sector): The number of sectors read from the device per second.
Disk Write (sector): The number of sectors written to the device per second.
Disk Read (KB): The number of kilobytes read from the device per second.
Disk Write (KB): The number of kilobytes written to the device per second.
Disk Request Size: The average size (in sectors) of the requests issued to the device.
Queue Length: The average queue length of the requests issued to the device.
IO Wait: The average time (in milliseconds) for I/O requests issued to the device to be served. This includes the time spent by requests in a queue and the time spent servicing them.
Disk Service Time: The average service time (in milliseconds) for I/O requests issued to the device.
IO CPU Time: Percentage of CPU time during which I/O requests are issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100%.

Process. Monitors for the disk section are available per process device.

Process Memory Usage: Resident size (kb). The non-swapped physical memory a task has used.
Process CPU Time: The task's share of the elapsed CPU time since the last update, expressed as a percentage of total CPU time.

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