Reducing High CPU Usage on Mimics

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High CPU Usage on Mimics may be a result of unoptimised configuration or a possible graphics card issue. Whilst it can sometimes be improved or completely solved, this cannot be guaranteed.

Displaying certain mimics can use a great deal of CPU time on one machine, but perhaps not on others. If a mimic makes use of any GDI+ functionality that is not hardware accelerated by the graphics subsystem, then you are certain to notice a significant performance impact. The reason for the high CPU usage is because if the GPU does not natively accelerate the GDI+ operation, the CPU has to emulate the functionality in software. Perhaps the most common types of GDI+ functionality that will cause an unaccelerated machine to struggle are mimic objects that use shading and mimics containing semi-transparent (Alpha blended) objects.

The performance problems are typically related to a complex page being frequently redrawn due to rapidly changing values, or the use of flashing colors.


Check that the issue is graphics related by bringing up the mimic on a PC with a modern graphics card and up to date drivers (e.g. a year or less old and made by ATI or nVidia).

If it is a graphics issue, check the drivers on the PC in question:

• Download and install the latest Chipset driver (VIA, Intel, SiS, nVidia etc)

• Download and install the latest graphics driver for your GPU, e.g. from ATI, nVidia, Intel etc.

In some cases this will entirely solve the problem (if the required hardware support was present in the GPU but not present in the default drivers on the PC). In others it will alleviate the problem (e.g. by using the latest chipset drivers the speed of communication with the graphics card will be improved).

While we always recommend using an up to date graphics card to achieve the best performance, sometimes the nature of a particular mimic will mean that the problem cannot be resolved through the graphics card drivers or the card itself. There are a number of things that can be done to help improve mimic performance:

• Minimize the use of complex graphical objects. For example, shapes with thousands of individual segments, highly complex gradient fills etc.

• Avoid using flashing colors on very complex mimics to stop ViewX having to redraw.

• Slow down the rate of flashing. ClearSCADA 2009 R1 contains support for reducing the flash rates.  See the Tools -> Options dialog in ViewX. In ClearSCADA 2007 R1.2 and later, this can be set via the registry. See the release notes for this version (ClearSCADA 2007 R1.2 Release Notes) for more details.

• Slow down the rate of data updates being sent from the server to client. As each change in data needs to be represented on the mimic, updates occurring very quickly on a complex mimic will cause high CPU load as ViewX renders the mimic in software when it can't utilise the grapics card. You can slow down these rates in the Tools -> Options dialog in ViewX.

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