Monitoring Memory Utilization

Operating system performance issues commonly involve process management, memory management, and scheduling. This section describes how to monitor memory utilization and identify problems such as paging and swapping.

To monitor memory utilization: 

1. From the Database Home page, under Host CPU, click the Load link.

   The Host page appears, showing the Performance subpage.

2. Select Memory Details from the View list.

   The Memory Details view of the Performance subpage appears.

   This view contains statistics about memory utilization, page scan rates, and swap utilization gathered over the last hour. The top 10 processes are also listed ordered by memory utilization.

3. Verify the current memory page scan rate using the Memory Page Scan Rate chart.

   The current value of the memory page scan rate is displayed below the chart. On UNIX and Linux, this value represents the number of pages scanned per second. On Microsoft Windows, this value represents the rate at which pages are read from or written to disk to resolve hard page faults. This value is a primary indicator of the kinds of faults that may be causing systemwide delays.

4. Click Memory Scan Rate.

   The Memory Page Scan Rate page appears.

   This page contains memory page scan rate statistics and related alerts over the last 24 hours.

   If you notice an unexpected spike in this value that is sustained through standard workload hours, then a memory performance problem might exist.

5. Verify the current memory utilization using the Memory Utilization chart.

   The Memory Utilization chart shows how much memory is being used. The current value of memory utilization is displayed below the chart. During standard workload hours, the value should not exceed the warning threshold (shown in yellow).

6. Click Memory Utilization.

   The Memory Utilization page appears.

   This page contains memory utilization statistics and related alerts generated over the last 24 hours.

   If you notice an unexpected spike in this value that is sustained through normal workload hours, then a memory performance problem might exist.

7. Verify current swap utilization using the Swap Utilization chart.

   The Swap Utilization chart shows how much swap space is being used. The current value of swap utilization is displayed below the chart. During normal workload hours, the value should not exceed the warning threshold.

8. Click Swap Utilization.

   The Swap Utilization page appears.

   This page contains swap utilization statistics and related alerts generated over the last 24 hours.

   If you notice an unexpected spike in this value that is sustained through normal workload hours, then a memory performance problem might exist.

9. Return to the Memory Details view of the Host Performance subpage and review the top processes in the Top 10 Processes (ordered by Memory) table.

   If a process is taking up too much memory, then this process should be investigated.

10. If a memory performance problem is identified, you can attempt to resolve the issue by doing the following:

    • Use Automatic Memory Management to automatically manage and distribute memory between the System Global Area (SGA) and the aggregate program global area (PGA aggregate).

    • Use the Memory Advisor to set SGA and PGA memory target values.

    • Use Automatic PGA Management to manage SQL memory execution.

    • Avoid running too many processes that use a lot of memory.

    • Reduce paging or swapping.

    • Reduce the number of open cursors and hard parsing with cursor sharing.