"Performance test" Linux performance monitoring commands--sar detailed

Reprinted: 52149993

The SAR command reports on the read and write of files, usage of system calls, disk I/O, CPU efficiency, memory usage, process activity, and IPC-related activities.

Command format: SAR [options] [-A] [-o file] t [n]
T is the sampling interval, n is the number of samples, the default value is 1
-o file means that the command result is stored in a binary format in a file, and file is a filename.
Options is a command-line option

Common options for SAR commands are as follows:

-A: Sum of all reports
-U: Output statistics about CPU usage
-V: Output statistics for inode, files, and other kernel tables
-D: Output activity information for each block device
-r: Output memory and swap space statistics
-B: Display statistics for I/O and transfer rates
-A: File read and write status
-C: Output process statistics, number of processes created per second
-r: Output memory page statistics
-Y: terminal equipment activity situation
-W: Output system Exchange activity information

CPU Resource monitoring:

Sampling every 5s, sampling 10 consecutive times, observing CPU usage, and storing the sampled results in binary form in Test_sar (view the contents of the binary file test, SAR command: Sar-u-F Test_sar)

Sar-u-O Test_sar 5 10

Output Item Description:

Cpu:all represents the average of the statistics for all CPUs.

%user: Displays the percentage of total CPU time that is running at the user level (application).

%nice: The percentage of total CPU time that is displayed at the user level for the nice operation.

%system: The percentage of total CPU time that is used to run at the core level (kernel).

%iowait: Displays the percentage of total CPU time that is used to wait for I/O operations.

%steal: The percentage of the hypervisor (hypervisor) that waits for a virtual CPU to serve another virtual process.

%idle: Shows the percentage of CPU idle time that takes up the total CPU time.

P.S:

1. If the%iowait value is too high, it indicates that the hard disk has an I/O bottleneck

2. If the value of the%idle is high but the system responds slowly, it is possible that the CPU waits for the allocated memory, at which time the memory capacity should be increased

3. If the value of%idle is consistently below 1, the system has a relatively low CPU capacity, indicating that the most necessary resource to be addressed in the system is the CPU.

Inode, file, and other kernel table monitoring:

Sample every 5 seconds, 10 consecutive samples, observe the status of the core table

Sar-v 5 10

Output Item Description:

DENTUNUSD: Number of unused entries in the directory cache

FILE-NR: Number of use of file handle (FileHandle)

INODE-NR: Number of uses of the index node handle (inodehandle)

PTY-NR: Number of Pty used

Memory and swap space monitoring:

Sample every 5s, sample 10 consecutive times, monitor memory paging

Sar–r 5 10

Output Item Description:

Kbmemfree: This value is basically the same as the free value in the command, so it does not include buffer and cache space.

Kbmemused: This value is basically the same as the used value in the free command, so it includes buffer and cache space.

%memused: This value is a percentage of kbmemused and total memory (excluding swap).

Kbbuffers and kbcached: These two values are the buffer and cache in the free command.

Kbcommit: Ensure that the current system requires memory (RAM+SWAP) in order to ensure that it does not overflow.

%commit: This value is a percentage of kbcommit and total memory (including swap).

Memory Paging Monitoring:

Sample every 5s, sample 10 consecutive times, monitor memory paging

Output Item Description:

PGPGIN/S: Indicates the number of bytes per second from disk or swap to memory (KB)

PGPGOUT/S: Indicates the number of bytes per second from memory to disk or swap (KB)

FAULT/S: The number of pages per second generated by the system, that is, the sum of the main and minor page faults (major +minor)

MAJFLT/S: The number of main pages generated per second.

PGFREE/S: Number of pages per second that are placed in the free queue

PGSCANK/S: Number of pages scanned per second by KSWAPD

PGSCAND/S: Number of pages scanned directly per second

PGSTEAL/S: The number of pages per second that are purged from the cache to meet memory requirements

%vmeff: Percentage of pages purged per second (pgsteal) in total scan page (Pgscank+pgscand)

I/O and transfer rate monitoring:

Sample every 5s, sample 10 consecutive times, and report buffer usage

Sar-b 5 10

Output Item Description:

TPS: Total I/O transfers per second for physical devices

Rtps: Total amount of data read from physical devices per second

Wtps: The total amount of data written to the physical device per second

BREAD/S: The amount of data read from the physical device per second, in blocks/s

BWRTN/S: The amount of data written to the physical device per second, in blocks/s

Process Queue Length and average load status monitoring:

Sample every 5s, sample 10 consecutive times, monitor process queue length and average load status

Sar-q 5 10

Output Item Description:

Runq-sz: Length of the run queue (number of processes waiting to run)

Plist-sz: Number of processes (processes) and threads (threads) in the process list

Ldavg-1: System average load for last 1 minutes (systemload average)

Ldavg-5: System average load over the last 5 minutes

Ldavg-15: System average load over the last 15 minutes

System Exchange activity Information monitoring:

Sample every 5s, continuously sampled 10 times, monitoring system exchange activity information

Sar-w 5 10

Output Item Description:

PSWPIN/S: Number of swap pages per second system swapped in (Swap page)

PSWPOUT/S: Number of swap pages per second system swapped out (Swap page)

Monitoring of equipment usage:

Sample every 5s, sample 10 consecutive times, report device usage

Sar-d 5 10-p

Parameter-P can print out the name of the disk device such as SDA,HDC, if not the parameter-p, the device node may be dev8-0,dev22-0

TPS: Number of times per second from physical disk I/O. Multiple logical requests are merged into one I/O disk request, and the size of one transfer is indeterminate.

RD_SEC/S: Number of Read sectors per second.

WR_SEC/S: Number of Write sectors per second.

Avgrq-sz: The average data size (sector) per device I/O operation.

Avgqu-sz: The average length of the disk request queue.

Await: The average elapsed time of each request, including the request queue wait time, in milliseconds (1 seconds =1000 milliseconds), from the request disk operation to the completion of the system processing.

SVCTM: The average time that the system processes each request, excluding the time consumed in the request queue.

%UTIL:I/O requests account for the percentage of the CPU, the higher the ratio, the more saturated the description.

1. When the value of Avgqu-sz is low, the equipment utilization is higher.

2. When the value of%util is close to 1%, it indicates that the device bandwidth is already full

To determine the system bottleneck, it is sometimes necessary to combine several SAR command options.

Suspected CPU bottlenecks, sar-u and sar-q can be used to view

Suspect memory bottlenecks and can be viewed with Sar-b, sar-r, sar-w, etc.

Suspected I/O bottlenecks and can be viewed with Sar-b, sar-u, sar-d, etc.

"Performance test" Linux performance monitoring commands--sar detailed