Specifications

100 IBM System z Personal Development Tool: Volume 3 Additional Topics
r = number of Linux processes waiting for run time
b = number of Linux processes sleeping
swpd = amount of swap space used (KB)
free = amount of idle memory (KB)
buff = amount of memory used as buffers (KB)
cache = amount of memory used as cache (KB)
si, so = Linux paging activity in KB/second
bi, bo = I/O activity in blocks/second
in = interrupts per second
cs = context switches per second
us = percent of CPU time in user mode
sy = percent of CPU time in kernel mode
id = percent of CPU time idle
wa = percent of CPU time waiting for I/O
Important data from vmstat includes the Linux swap rates (si, so); any number here can
degrade 1090 performance. If the 1090 suffers a page fault, then the whole System z CP
operation must wait for the page fault to be resolved. The wa statistic (CPU percentage
waiting for I/0) provides an indirect indication of I/O overload.
The top command provides data about individual Linux processes. We are most interested in
the emily process (which is the name of the Linux process representing the CP), but
information about various device manager processes can be useful in spotting bottlenecks.
Enter q from the keyboard to terminate the top command.
$ top
top - 11:14:14 up 1:24, 3 users, load avg: 1.26, 1.15, 1.02
tasks: 128 total, 1 running, 121 sleeping, 6 stopped, 0 zombies
CPU(s): 49.9% us, 0.2% sy, 0.0% ni, 49.7% id, 0.0% wa 0.0% hi, 0.0% si
mem: 3111660k total, 2719204k used, 392456k free, 105356k buffers
swap: 2104504k total, 0k used, 2104504k free, 2397740k cached
PID USER PR NI Virt RES SHR S %CPU %MEM TIME COMMAND
7040 ibmsys1 25 0 1549m 1.5g 1.5g S 100 49.6 35:41.2 emily
7051 ibmsys1 16 0
1510m 36m 36m S 0 1.2 0:03.1 awsckd
The Xosview program provided with openSUSE Linux, if installed, can be started from
System  Monitor  XOsview. It provides a very dynamic display of individual processor
usage, memory usage, paging, and so forth. This program uses X11 graphics and creates
more overhead than vmstat or top. If you are concerned about paging exposures on your
system, we suggest that XOsview be started before starting the 1090.
The XOsview program, by default, uses a split line to display PC processor activity. Half of the
line indicates instantaneous activity and the other half of the line shows an average rate with
a decay factor averaged over several seconds. The decay presentation may be removed as
follows:
# cd /usr/lib/X11/app-defaults
# gedit XOsview
Change *cpuDecay from True to False.