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the conclusions. First, the user opens the program
Isah and performs some actions. Next, the user opens
Valor Universal ¡viewer and loads a PCB data model.
Thereafter, the user opens Paperless, which is an Oracle
database, and loads some documents. Finally, the user
closes all documents and programs, after which the
test ends.
2) Logging data: During the execution of the actions, data has to be logged. This can be done in two
ways: by using a third-party performance monitoring
tool or by using the Windows Performance MMC
(Microsoft Management Console) snap-in. The first way
offers more enhanced analysis capabilities, but is also
more expensive. For this reason, we use the MMC
which has sufficient features in our situation. In the
MMC we can add performance counters that log to
a file during the test. After the test, the file can be
imported into Microsoft Excel to be examined. For
this performance test, we need to choose counters to
examine the speed of the process and the network usage.
These are the most important factors. Therefore the
counters we add are:
• Process > Working Set > Total
• Memory > Pages Output/sec
• Network Interface > Bytes Total/sec
• Network Interface > Output Queue Length
By default, the system records a sample of data
every fifteen seconds. Depending on hard disk space
and test size, this sample frequency can be increased
or decreased. Because the test endures only a few
minutes, we choose a sample frequency of just one
second.
3) Specifications: The traditional workstation has an
Intel Core2 CPU, 2.13 GHz and 1.99 GB of RAM. The
installed operating system is Microsoft Windows XP
Professional, v. 2002 with Service Pack 3. Its network
card is a Broadcom NetXtreme Gigabit Ethernet card.
The Terminal Server has an Intel Xeon CPU, 2.27 GHz
and 3 GB of RAM. The operating system is Microsoft
Windows Server 2003 R2 Standard Edition with Service
Pack 2. It has an Intel PRO 1000 MT network card.
C. Discussion
1) Speed: The most important factor is obviously
the execution speed of the test. When performing the
actions on the traditional desktop, it takes an average
of 198 seconds to perform all predefined tasks. On the
Terminal Server on the other hand, it only takes an
average of 150 seconds. This means that in this case
the Terminal Server desktop environment is 48 seconds
or approximately 24% faster than the regular desktop.
Saving almost a minute of time when performing a
series of tasks that takes only about 3.5 minutes is a lot.
Fig. 1.
Fig. 2.
Output from the Process > Working Set > Total counter
Output from the Memory > Pages Output/sec counter
2) Memory: Figure 1 shows the output from the
working set counter. This counter shows the total of
all working sets of all processes on the system, not
including the base memory of the system, in bytes. First
of all, the figure also shows the difference in execution
speed we discussed in II-C1. We can see that for the
same series of actions, it takes significantly less time to
perform then on the Terminal Server desktop.
Another conclusion that this data shows is the memory usage. When executing tasks on the regular desktop,
the memory usage varies between 400 MB and 600
MB, whereas the memory usage in the virtual desktop
environment varies only between 350 MB and 450 MB.
We can conclude that the virtual desktop uses slightly
less memory than the regular desktop and the variations
are smaller.
The output from the Pages Output/sec counter is
shown in figure 2 and indicates how many times per
second the system trims the working set of a process
by writing some memory to the disk in order to make
physical memory free for another process. This is
a waste of valuable processor time, so the less the
memory has to be written to the disk, the better.
Windows doesn’t pay much attention to the working
set when physical memory is plentiful: it doesn’t trim
the working set by writing unused pages to the hard
disk. In this case, the output of the counter is very
low. When the physical memory utilization gets higher,
Windows will start to trim the working set. The output
from the Pages Output/sec counter is much higher.