SOS Current Resource Trends
SOS/3000 has five Current Resource Trends screens that allow you to quickly see the trend of
key performance areas over the duration of the current SOS/3000 session:
Current Resource Trend Screen Keys
Each of the Current Resource Trend Screen key is listed and explained in the following table.
Table 11.1 Current Resource Trend Screen command keys
|
Key
|
Usage
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blank
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Refresh screen
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B
|
Beginning data request
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C
|
CPU trend data
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D
|
Disc trend data
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E
|
Return to SOS Global screen
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J
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Jump to new screen
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L
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Print hardcopy
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M
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Memory trend data
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S
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Jump to the SOS Screen Selection menu.
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T
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Response trend data
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V
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Live data request
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W
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Mode switches trend data
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X
|
Exit
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!
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Execute shell commands
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:
|
Execute shell commands
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*
|
Switch function key sets
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/
|
Select time request
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}
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Scroll backward request
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[
|
Skip forward request
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]
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Skip backward request
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Current Resource Trend Search Keys
From each Current Resource Trend screen, there will be a set of search keys available for
navigation.
Table 11.2 SEARCH KEYS
|
Search Key
|
Description
|
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F1 - SCROLL AHEAD
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This key displays the next page of data.
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F2 - SCROLL BACK
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This key displays the previous page of data.
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F3 - SKIP AHEAD
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This key produces a prompt for the number of samples to skip. After entering a valid number, that number of samples will be bypassed in a forward direction. The data displayed will be from that point forward.
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F4 - SKIP BACK
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This key performs like the SKIP AHEAD. When a valid number is entered, that number of samples will be skipped backward. The data displayed will then be from that point forward.
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F5 - SELECT TIME
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This key prompts for a time at which you want to begin examining data.
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F6 - START OF DATA
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This key will take you to the first interval available in the Current Trends.
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F7 - END OF DATA
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This key will take you to the current interval.
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F8 - MAIN KEYS
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This key will return you to the main keys in the Current Trends screen.
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The SOS Resource Trend screen data items are described on the next pages.
CPU Trends Screen
To access the CPU Trends screen:
Type S from the SOS Enter command: prompt to view the Screen Selection Menu.
From the Screen Selection Menu, type A (Current Resource Trend Screen). A sample of this screen is shown in Figure 11.1.
Figure 11.1 SOS CPU Trends screen
The CPU Trends screen presents the following CPU utilization data collected in 10-second time
intervals:
Percentage of CPU utilized
Percentage of idle time
Response time in seconds
Each letter-width space on the CPU utilization bar graph represents approximately 2 percent of
the CPU’s time for the current interval. The code letters correspond to the CPU activities
described in
Table 11.3. Where a block of spaces on the bar graph is bordered by two instances
of one code letter (e.g., S...S), that corresponding activity (e.g., executing system calls and code)
would account for the CPU% range bordered by the two letters. For example, in the example
above, the CPU utilization for 10-second interval beginning 15:11 (the first line) shows:
Approximately 2 percent of CPU time was spent executing stem processes and carefully placed high priority user processes in the BS queue.
Approximately 42 percent of the CPU time was spent executing lower priority jobs in the ES queue.
Approximately 2 percent was spent managing overhead.
Approximately 2 percent of the time the CPU was paused while waiting for disc I/O.
53 percent of the time the CPU was idle.
Response time for that interval averaged 0.3 seconds.
The code letters used in the CPU utilization bar graph are described in the next table.
Table 11.3 CPU Trend states or activities
|
Code
|
Statistic
|
Description
|
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A
|
AS queue %
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The percentage of CPU time spent executing high priority system processes.
|
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B
|
BS queue %
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The percentage of CPU time spent executing both system processes and some high priority user processes.
|
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C
|
CS queue %
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The percentage of CPU time spent executing interactive user processes.
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D
|
DS queue %
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The percentage of CPU time spent executing high priority batch jobs.
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E
|
ES queue %
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The percentage of CPU time spent executing lower priority jobs.
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M
|
Memory management %
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The percentage of CPU time spent managing memory.
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O
|
Overhead %
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The percentage of CPU time spent managing overhead (ICS/OH and dispatch).
|
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P
|
Paused for Disc %
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The percentage of time the CPU was paused, waiting for disk I/O.
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Idle %
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The space between the end of the bar and the 100% point indicates the percentage of time the CPU was idle.
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Resp Time
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The average response time for that interval.
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Function Keys
The other four Current Resource Trends screens are accessed via function keys at the bottom of
the CPU Utilization Trends screen. The function keys under the CPU Utilization Trends screen are
shown in the following table.
Table 11.4 CPU Utilization Trends screen function keys
|
Key
|
Description
|
|
F1 - LIST HARDCOPY
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Prints a hardcopy of the displayed trend report.
|
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F2 - CPU TREND
|
Displays the CPU Utilization Trends screen (Figure 19.1). This screen reports CPU.
|
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F3 - MEMORY TREND
|
Displays the Main Memory Utilization Trends screen (Figure 19.2). This screen reports memory clock cycle and swaps per launch ratio.
|
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F4 - DISC TREND
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Displays the Disc I/O Utilization Trends screen (Figure 19.3). This screen reports Read and Write disc I/O rate and average disc queue length.
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F5 - RESPONSE TREND
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Displays the Response and Transaction Trends screen (Figure 19.4). This screen reports Transaction rates per minute.
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F6 - MODE SWITCHES
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Displays the Mode Switch Trends screen (Figure 19.5). This screen reports NM to CM and CM to NM mode switch rates.
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F7 - SEARCH KEYS
|
|
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F8 - MAIN SCREEN
|
Return to SOS/3000 main screen.
|
|
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NOTE When you exit SOS/3000 all of the Currents Trends data will be lost. If you want to review past data, see "SOSLOGX".
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Main Memory Trends Screen
The Main Memory Trends screen displays statistics pertaining to memory utilization in 10-second
time intervals.
Figure 11.2 SOS Main Memory Utilization Trends screen
The data items presented in the Main Memory Trends screen are described in
Table 11.5.
Table 11.5 SOS Main Memory Utilization Trends data items
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Data Item
|
Description
|
|
Page Faults/sec
|
This bar graph shows the average memory page faults per second during the 10-second interval. Each character space in the bar graph represents two page faults per second. If the number exceeds the range of the graph, a greater-than character (>) will display.
The page fault rate indicates whether or not there is adequate memory. A low number is desirable.
|
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Swaps/Launch
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This is the ratio of the number of swap-ins to the number of launches that occurred during the interval. This can also be a good indicator of memory pressure.
Performance Tip
A large swaps per launch ratio means that for every time a process came up to bat with the CPU, necessary segments were not present in main memory, and the process was disabled. A ratio consistently greater than.5 indicates a possible memory shortage. Check other memory indicators for confirmation. If your memory is indeed inadequate, you can either reduce the memory load or increase memory hardware.
|
Disc I/O Utilization Trends Screen
Figure 11.3 SOS Disc I/O Utilization Trends screen
The data items presented in the Disc I/O Utilization Trends screen are described in
Table 11.6.
Table 11.6 SOS Disc I/O Utilization Trends data items
|
Data Item
|
Description
|
|
Disc I/O rate (second)
|
A total rate of both reads and writes per second (Rt). These numbers reflect the actual physical transfers between main memory and a particular disc device (Ldv-n).
|
|
Avg Queue Length
|
The average length of the request queue for that particular disc drive when another disc I/O request arrives at that drive.
|
Response and Transaction Trends Screen
Figure 11.4 SOS Response and Transaction Trends screen
The data items presented in the Response and Transaction Trends screen are described in
Table
11.7.
Table 11.7 SOS Response and Transaction Trends data items
|
Data Item
|
Description
|
|
Transaction Rate (per minute)
|
This is an estimated number of terminal reads per minute based on the current interval’s workload.
|
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Average Response Time (sec)
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This is the average time it takes from pressing the C/R or Enter key to when the user is supplied prompt.
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Mode Switch Trends Screen
Figure 11.5 SOS Mode Switch Trends screen
The data items presented in the Mode Switch Trends screen are described in
Table 11.8.
Table 11.8 SOS Mode Switch Trends data items
|
Data Item
|
Description
|
|
NM -> CM (per second)
|
These numbers represent the number of native mode (NM) to compatibility mode (CM) switches performed per second for the current interval, as well as cumulatively.
Performance Tip
A native mode to compatibility mode switch occurs when a piece of code that is executed reverts from native mode language to a translated form (compatibility mode). This operation is quite expensive for the system to perform and should be minimized. Depending on the system size, about 50 per second may indicate an overhead drain on the CPU. It is best to “go native” whenever possible; but, going native can cause an increased dependency on the application design.
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CM -> NM (per second)
|
These numbers represent the number of compatibility mode to native mode switches performed per second for the current interval, as well as cumulatively.
Performance Tip
A compatibility mode to native mode switch occurs when a piece of code that is executed reverts from compatibility mode to native mode. This operation is not as expensive to perform as is NM to CM switching. The system can sustain many more without excessive degradation to the system. Depending on the system size, more than about two hundred per second can be sustained without being an excessive overhead drain on the CPU.
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General Comments
