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Lund Performance Solutions


SOS Memory Summary

The Memory Summary Screen

The Memory Summary screen provides a detailed look at memory and virtual memory performance.


Figure 11.1 SOS Memory Summary screen
To access the Memory Summary screen from any SOS display screen:
  • Type s from the SOS Enter command: prompt to view the Screen Selection Menu screen.
  • From the Screen Selection Menu screen, enter m (Memory Summary). The Memory Summary screen will display. Figure 11.1 shows an example of the screen.
  • Memory Summary Screen Display Items

    MEM/VM ALLOCATION

    The MEM/VM ALLOCATION portion of the Memory Summary screen shows how RAM and virtual memory are allocated on the system. The data items are described in the following table.
    Table 11.1 SOS MEM/VM ALLOCATION data items
    Data Item
    Statistics
    Description
    Mem
    Size
    The amount of RAM (MB) installed on the system.
    Used
    The amount of RAM (MB) used during the interval.
    Free
    The amount of RAM (MB) free (unused) on the system.
    VM
    Size
    The amount of virtual memory (MB) enabled on the system.
    Used
    The amount of virtual memory (MB) used during the interval.
    Free
    The amount of virtual memory (MB) free (unused) on the system.

    PROC MEM STATUS

    The PROC MEM STATUS portion of the Memory Summary screen shows where processes are currently located from a memory viewpoint. Each data item is described in the next table.
    Table 11.2 SOS PROC MEM STATUS data items
    Data Item
    Description
    Run
    The number of swapped processes that are ready to run. In other words, the length of the CPU run queue.
    Sleep
    The number of processes that are sleeping.
    Total
    The total number of processes swapped during the interval.

    PAGING

    The PAGING portion of the Memory Summary screen displays detailed statistics on paging activity for the interval. Each data item is described in the following table.
    Table 11.3 SOS PAGING data items
    Data Item
    Description
    In (/s)
    The number of swaps in per second.
    Out (/s)
    The number of swaps out per second.
    In (byte/s)
    The number of bytes swapped in per second.
    Out (byte/s)
    The number of bytes swapped out per second.
    #In
    The number of swaps in.
    #Out
    The number of swaps out.

    PAGE SCANNER

    The PAGE SCANNER portion of the Memory Summary screen displays data the page scanning process for the interval. Each data item is described in Table 11.4.
    Table 11.4 SOS PAGE SCANNER data items
    Data Item
    Description
    Page Recs
    The number of pages reclaimed per second.
    Page Scans
    The number of pages scanned by the page scanner per second.
    Ave Page Res
    The average page residence time in milliseconds.
    The Ave Page Res value the average amount of time a page is able to stay in memory. The default value is 600, which means that pages are not being forced from memory. Lower numbers indicate that pages are being forced out of memory.

    MEMORY MANAGEMENT CONFIG

    The MEMORY MANAGEMENT CONFIG portion of the Memory Summary screen displays the values of key memory management variables. Each data item is described in the following table.
    Table 11.5 SOS MEMORY MANAGEMENT CONFIG data items
    Data Item
    Description
    lotsfree
    The upper bound for paging. Once paging has started, it will continue until free memory (refer to "MEM/VM ALLOCATION") is larger than lotsfree.
    desfree
    The lower bound for paging. When free memory drops below desfree, paging begins.
    minfree
    The threshold at which the system considers itself to be out of memory. At this point, the system will start deactivating processes.
    throttlefree
    The threshold at which any process that attempts to get another page will be suspended until the amount of free memory exceeds desfree.
    priority paging
    The priority paging value is either 0 (zero) or 1.
  • If 0, priority paging is not enabled.
  • If 1, priority paging is enabled.
  • Priority paging, when enabled, modifies the paging algorithm to page out data pages before text, heap, and stack.
    maxpgio
    The maximum number of page I/O operations per second that the system will schedule.
    page size
    The size of pages in bytes.
    fastscan
    The fastest scan rate in pages per second. This value corresponds to an empty free list.
    slowscan
    The initial scan rate in pages per second. The initial scan rate is measured when page scanning first starts.

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