QNX 4 on VmWare

QNX4 poor HDD performance in vmware virtual machine. virtual machine is extremely slow during ‘pax’ ‘freeze’ and ‘melt’ operations. virtual machine is allowed to use 2 processors and has 128Mb of RAM allocated. Single 5GB flat .vmdk file for system.

installed under Windows 2003 server on Dell Poweredge server.

Anyone else running this environment under VmWare that can give me any performance tweaks??


There’s not much point in giving QNX 4 2 processors, as it will only use one. I suppose you might be able to run two QNX 4 VM’s and then find a way to network them together, in which case you could write code that would allow the use of multiple processors. This would not help your I/O performance. The QNX 4 file system was a big improvement over QNX 2. By default the system allocate 1/4 of the memory to a file cache. The file system would dynamically learn what type of access you were doing, so in the case of a file copy, it would increase the size of read ahead I/O’s it was requesting. I don’t know how VM vitualizes file I/O, but let’s suppose it provides a virtual eide controller. Let’s further suppose that the QNX 4 driver is using PIO. In this case the driver would be moving each sector byte by a virtualized inp instruction. This could certainly cause a big performance hit. If so, the question is why the driver isn’t using DMA?
This is just a big guess on my part.

Indeed using 2 process is totally useless.

Make sure your vmdk is not fragmented. Also make sure windows has enough memory.

In my experience hdd is about 50% slower when there is a lot of random access. For sequential it can, in some cases, be faster ;-)

Try Fsys.atapi.

Also try -a option to Fsys.