[Xastir] Speed issues moving maps.

[Curt, WE7U]

On Sun, 20 Mar 2011, jd at jdwallace.com wrote:

> When I try to pan or zoom I experience long refresh times on the map (10-20 sec). I'm attempting to load 1-5 maps at a time. I'm using scanned maps in .geo format and USGS DRG maps.

I have a feel for the DRG's.  How big are the other scanned maps (pixels)?  If they are large, consider breaking them up into pieces so that as you zoom in you load fewer maps.  Also consider using maps that are appropriate for the scale, and only go to the detailed maps when you need that level of detail.  Seems I've said some of this before!


> I'm using Xastir built from CVS on Ubuntu 10.10 running as a VM on VirtualBox. The host is 8 core/8GB RAM with half of those resources allocated to the VM.

Have you installed the guest drivers for VirtualBox into the Ubuntu 10.10 OS?  I'm not doing anything using VM's right now, but I recall a major speedup after installing the guest OS drivers and rebooting the guest.

What video card are you using?  That can make a big difference.  Maps are quite fast on my work and my home machines, running native OpenSuSE-11.3 64-bit on each, NVidia PCIe card in the work machine, NVidia in the motherboard chipset on the home machine.  The work machine is faster at drawing maps, even though they are both dual-core machines, similar speeds and memory.

> Can someone share some optimization tips to speed map rendering when panning or zooming?

There's only so much that can be done with the current code.  All of the packet processing AND the map drawing is done in the main thread.  The GUI stuff must be done there (limitation of X11), but the packet processing could be moved to another thread at some point.

-- 
Curt, WE7U.        http://www.eskimo.com/~archer
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