When the topas command is started, it displays all subsections for which hot entities are monitored. Tip: When there is no WPAR specific information for a metric, the system-wide value is displayed for that metric in inverted background that is, white text and black context. The following table provides the details for the subsections that the topas command displays: Item Description Processor utilization This subsection displays one-line report summary of all the processor usage. Pressing the c key only once turns this subsection off. If more than one processor exists, a list of processors is displayed by pressing the c key twice. Pressing the c key thrice displays a bar chart showing cumulative processor usage.
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Quit topas topas Tips The right hand side of the default topas screen is hard-set and cannot be toggled. It will only display as many lines as fit in a default terminal size.
The left hand side items can be toggled with keys for each section and frequently be expanded to use the entire screen with additional data not available in the default screen. Columns on the left hand side of the screen and the full screen modes can be sorted by moving the cursor between the section headings.
The current sort order can be determined by the highlighted section heading. It will allow you to identify the offending process that is consuming CPU on a system. Once a system is identified as CPU bound from the main screen of topas, you only need to look at the process list to see the process that is driving the usage.
Finding an offending process is the easy part of the battle when diagnosing CPU issues. The next step is to determine how the CPU is consumed. Application tools such as those found in databases can be helpful in this area. AIX provides a number of profiling tools that tell what an application is doing. When looking at total CPU utilization, one should watch for natural plateaus that form when a single threaded process becomes CPU bound on a multiple processor system.
Symptoms of this show up as a consistent CPU utilization number that is at or near a fraction of the total CPU capacity of the system. While not directly a CPU related performance measurement, poor processor affinity on a LPARed system will cause additional CPU time as memory is accessed from remote cache or memory locations.
Processor affinity can be monitored with the lparstat and mpstat tools. This can be monitored using the -d option to mpstat and looking for higher numbers in SXrd columns, where an increasing value of X represents poorer processor affinity.
Finally, it is essential to understand the underlying nature of a virtualized system. The number or parts of physical CPUs that back a virtual processor is key in understanding how loaded the system is. Memory High memory utilization manifests itself as CPU bound, but over consumption or over-subscription of memory takes the form of paging. This is when processes have allocated and used more memory than the system physically has. To maintain the increased memory footprint of each process the system must write portions of memory to disk in a paging space.
The standard method of measuring memory is by looking for paging. Most healthy systems will page to some degree to favor more active applications and files to cache. So when looking at paging statistics it is key to note how much paging space is in use, but how much paging activity is happening at this time. The amount of paging space in use is visible on the main screen of topas. It should be noted that a higher value in paging space utilization may not necessarily represent memory stress.
It is possible that a one time event may have pushed many unused pages to disk. This does not tell how much of the application is paged out but how much of the application memory is backed by paging space. It is not necessarily useful to see what application is paged out as this is not as relevant as the fact that the system is paging and how much the system is paging.
Disk Extended disks statistics are viewable using the D runtime or -D command line option to topas. In both the default screen and the extended disk statistics screen you can sort the disk results based upon various fields by moving the cursor over that field. The transfer rate is an indication of how much data is moving between the disk and the system.
This time spent seeking will subtract from the amount of data that can be transfered. It is not a measurement of how much the disk is actually transferring or how efficient the disk is. When used with the transfer rate it can be used to determine what the maximum transfer rate is. When looking for data beyond what topas gives the next place to look is to the iostat command.
This is a rather comprehensive tool in terms of data that it provides for disk statistics. Once a hot disk has been found, filemon can be used to watch what files are being accessed and fileplace can be used to look for fragmentation in individual files. Network topas does not display more networking information than what is available on the default screen. Additional information is available from the netstat or XXXstat where XXX is the interface type - such as entstat, tokstat, etc The following command will display a screen full of detailed device statistics every second: while [ 1 ] ; do clear ; entstat ent0 ; sleep 2 ; done A similar command for en0 is: netstat -I en0 2 There are a number of application specific tools, diagnostic aids, and trace based tools for network analysis.
These include, but are not limited to: nfsstat, netpmon, iptrace, ipreport, ipfilter.
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Quit topas topas Tips The right hand side of the default topas screen is hard-set and cannot be toggled. It will only display as many lines as fit in a default terminal size. The left hand side items can be toggled with keys for each section and frequently be expanded to use the entire screen with additional data not available in the default screen. Columns on the left hand side of the screen and the full screen modes can be sorted by moving the cursor between the section headings. The current sort order can be determined by the highlighted section heading. It will allow you to identify the offending process that is consuming CPU on a system. Once a system is identified as CPU bound from the main screen of topas, you only need to look at the process list to see the process that is driving the usage.