📊 Process Monitoring (pidstat)

pidstat reports the CPU, memory, I/O and context-switch activity of processes.

Report the process context-switching activity

 1# pidstat -w -p 3446 2 5
 2Linux 3.10.0-123.13.2.el7.x86_64 (localhost.localdomain) 12/26/2014
 3_x86_64_ (1 CPU)
 407:23:38 AM UID PID cswch/s nvcswch/s Command
 507:23:40 AM 0 3446 0.50 0.00 sshd
 607:23:42 AM 0 3446 0.50 0.00 sshd
 707:23:44 AM 0 3446 0.50 0.00 sshd
 807:23:46 AM 0 3446 0.50 0.00 sshd
 907:23:48 AM 0 3446 0.50 0.00 sshd
10Average: 0 3446 0.50 0.00 sshd

• cswch/s : number of voluntary context switches the task made per second. (A voluntary context switch occurs when a task blocks because it requires a resource that is unavailable.)
• nvcswch/s : number of non-voluntary context switches the task made per second. (An involuntary context switch takes place when a task executes for the duration of its time slice and is then forced to relinquish the processor.)

Page faults and memory

1pidstat -r -p <PID> 3600 72    # every hour, 72 times - practical for long-term monitoring.
2
3pidstat -r -p <PID> 50 12
407:26:44 PM       PID   minflt/s  majflt/s     VSZ    RSS   %MEM  Command
507:27:34 PM     13775      1.64      0.00 34957320 18183312  55.30  java

• minflt/s : number of minor faults the task has made per second — those which did not require loading a memory page from disk.
• majflt/s : number of major faults the task has made per second — those which required loading a memory page from disk.
• VSZ : Virtual Size — the virtual memory usage of the entire task in kilobytes.
• RSS : Resident Set Size — the non-swapped physical memory used by the task in kilobytes.

Disk I/O

1pidstat -d -p <PID> 50 12

pidstat -d reports I/O statistics (kernels 2.6.20 and later only). The following values are displayed:

• kB_rd/s : number of kilobytes the task has caused to be read from disk per second.
• kB_wr/s : number of kilobytes the task has caused, or shall cause, to be written to disk per second.
• kB_ccwr/s : number of kilobytes whose writing to disk has been cancelled by the task. This may occur when the task truncates some dirty pagecache; in that case, some I/O which another task was accounted for will not happen.

CPU (default mode)

pidstat reports the CPU usage by default.