Hi there,
Might be helpful information to others as well… After a couple of days of troubleshooting why certain machines render much slower than others, we have found that in some cases, depending on how the processes are started, they can get a “very low” (background) IO priority assigned to them. This is different from process priority. The new IO priorities have been introduced post vista and is not shown in the task manager. The most convenient tool that shows this information is either “Process Hacker”, or monitoring of the transfer packets using “Process Monitor”, or - if the process traffic shows up in it - the windows Resource Monitor.
This issue caused renders to go at 1/5th or 1/20th of the expected speeds, depending on the IO requirements of the jobs.
In our case, a combination of factors - which we are still investigating - on some machines caused the deadline slave to end up with a very low IO priority, causing their render processes to also be extremely slow.
We have implemented a fix that forces the IO priorities on our main processes, using the fairly undocumented NtSetInformationProcess winapi function.
cheers
laszlo