Within the discipline of software performance engineering (SPE), application response time monitoring refers to the capability of instrumenting application requests, transactions and other vital interaction scenarios in order to measure their response times. There is no single, more important performance measurement than application response time, especially in the degree which the consistency and length of application response time events reflect the user experience and relate to customer satisfaction. All the esoteric measurements of hardware utilization that Perfmon revels in pale by comparison.
Of course, performance engineers usually still want to be able to break down application response time into its component parts, one of which is CPU usage. Other than the Concurrency Visualizer that is packaged with the Visual Studio Profiler that was discussed in the previous post, there are few professional-grade, application response time monitoring and profiling tools that exploit the …
This is a continuation of a series of blog posts on VMware memory management. The previous post in the series is here.
Ballooning Ballooning is a complicated topic, so bear with me if this post is much longer than the previous ones in this series.
As described earlier, VMware installs a balloon driver inside the guest OS and signals the driver to begin to “inflate” when it begins to encounter contention for machine memory, defined as the amount of free machine memory available for new guest machine allocation requests dropping below 6%. In the benchmark example I am discussing here, the Memory Usage counter rose to 98% allocation levels and remained there for duration of the test while all four virtual guest machines were active.
Figure 7, which shows the guest machine Memory Granted counter for each guest, with an overlay showing the value of the Memory State counter reported at the end of each one-minute measurement interval, should help to clarify the state of VMware memory-managemen…
To assess the overall impact of the VMware virtualization
environment on the accuracy of the performance measurements available for
Windows guest machines, it is necessary to first understand how VMware affects
the clocks and timers that are available on the guest machine. Basically,
VMware virtualizes all calls made from the guest OS to hardware-based clock and
timer services on the VMware Host. A VMware white paper entitled “Timekeeping in VMware
Virtual Machines” contains an extended discussion of the clock and timer
distortions that occur in Windows guest machines when there are virtual machine
scheduling delays. These clock and timer services distortions, in turn, cause
distortion among a considerably large set of Windows performance counters,
depending on the specific type of performance counter. (The different types of
performance counters are described here…