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will the pgfree/s command happen without pgscand/s? How and what is the difference between pgfree/s and pgscank/s?

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Welcome to the StackExchange @Ajay Ponugoti

$ man sar

-B     Report paging statistics.  The following values are displayed:

pgpgin/s Total number of kilobytes the system paged in from disk per second. pgpgout/s Total number of kilobytes the system paged out to disk per second. fault/s Number of page faults (major + minor) made by the system per second. This is not a count of page faults that generate I/O, because some page faults can be resolved without I/O. majflt/s Number of major faults the system has made per second, those which have required loading a memory page from disk. pgfree/s Number of pages placed on the free list by the system per second. pgscank/s Number of pages scanned by the kswapd daemon per second. pgscand/s Number of pages scanned directly per second.
  • What is the difference between "system per second and "kswapd daemon per second"? My doubt is both are system kernel related tasks but what is the reason behind we have 2 – Ajay Ponugoti May 24 at 4:42
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There are different "system per/sec"

There is:

System\File Read Operations/sec: is the combined rate of file system read requests to all devices on the computer, including requests to read from the file system cache.

System\File Write Operations/sec is the combined rate of the file system write requests to all devices on the computer,

System\System Up Time is the elapsed time (in seconds) that the computer has been running since it was last started.

System\System Calls/sec is the combined rate of calls to operating system service routines by all processes running on the computer.

The kswapd daemon scans for available pages for the free list if the number of pages on the list becomes too low. This daemon only runs when needed.

  • Thanks for the valuable info. One last question - then what is Number of pages scanned directly per second? with respect to kswapd ? – Ajay Ponugoti May 24 at 5:39

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