> Maximizing Performance for Load Test Applications
LoadTest runs stress the driver computer a lot. Here are some
practical hints on how to get the MOST out of eValid when you are
running LoadTests:
(1) Use eVlite. eVlite, available in Ver. 3 of eValid, can
easily generate quantities of "background activity", albeit
not the full context-preserving transactions which eValid can
handle.
The idea here is to keep the servers busy so you can
experiment with response times from multiple full-fidelity
eValid playbacks being served by a [very] busy server. Each
eVlite takes about 8 MBytes of RAM, and can play back up to
1000 threads, with each thread representing a separate user
session.
(2) Carefully Budget RAM Use. Each eValid instance takes about 9
MBytes of RAM and each eVlite takes about 8 MBytes of RAM. If
you use the System Summary information on your machine you can
read out the "Available Physical Memory" value. This is the
value against which you will want to budget your eValid/eVlite
usages.
Adding additional memory is relatively inexpensive; recently
the price for 512 MByte chips was about $80.
(3) Increase The Available RAM in Video Card. When you have the
minimal amount of available RAM in the video card, i.e. 4
MBytes, strange results may appear in the PC display with high
eValid parallelism values. From what we observe that the
technical results eValid produces themselves do turn out to be
correct; it is only the display you see that is goofy.
We get most of our data from a 512 MByte machine that has a
hi-performance video card which has 64 MBytes of RAM.
(4) Include Delays To Decrease Effective Playback Duty Cycle. The
duty cycle on eValid goes down if you have a higher percentage
of wait time and accordingly a larger number of eValid's can
run simultaneously if they are not all running "as fast as
possible."
We have observed very wide variations between scripts with a
100% duty cycle and those with a 10% duty cycle, for example.
(5) Use Multiple Playback Machines. To help out our customers we
will be pleased to issue EVAL keys for you so that you can
replicate your tests to multiple machines until you sort out
the performance/capacity issue on your main machine(s).
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