RA 2008 and Multithreading

[mmodernc]

What were the performance enhancements touted in RA 2008.
I put one session of revit on chip1 and the second on chip 2 onna core duo Toshi p100 Satellite.
I opened files from R9 in 2008 in the second session on the second chip and the cpu useage of the second flattened out at peak while the cpu usage of the first chip waffled along..
I then allocated both sessions to both chips and did the same - both chips seemed to be working and neither flattened out at the peak.
Does this mean that the revit file in the second revit session was working on both chips at the same time when both sessions of revit were set to operate on both chips.
i.e. is RA2008 multithreading?

[jtj]

Revit isn't multi-threaded. It's a single threaded application... which IMHO is ridiculous considering the current state of the hardware world.

Got a dual processor, quad core workstation? Fantastic, Revit will use 1/8 of your processing power.

Got a core-duo laptop (like my M90) and you'll utilize a whopping 50%.

The only exception to this is accurender -- it can pull a full 100% of your CPU.

Keep the task manager open and watch your utilization. It kills me everytime I look at it.

[GuyR]

Revit isn't multi-threaded. It's a single threaded application... which IMHO is ridiculous considering the current state of the hardware world.

Revit is multi-threaded , it's just not able to optimally use cores in the areas we'd like them too. And it's not because they don't want to. Show me one 3D CAD system that scales with X cores? The reality is while X cores might have been a great way to improve processor performance it's a difficult way to improve software performance. Particularly for applications such as Revit. This isn't a weekend job to fix. The techniques and tools available to help developers utilise X cores in efficient ways are changing and improving all the time. Just don't expect they'll one day flick a switch and Revit will suddenly scale for X cores. It'll be a gradual improvement I think.

Guy

[Andrew Dobson]

Task manager reports that Revit is using multiple threads (it is using 16 at the moment for me) but for some technical reason it doesnt seem to be able to split these across more than one processor. Does anyone understand why?

[jtj]

I got into this same "multi-threaded" discussion with a coworker... call it whatever you want, but if a program is only using 1/x (x being the number of available CPUs), I'm going to call that a single threaded app.

Guy: Yes, essentially you're rewriting a significant portion of the program code to make it an effective multi-threaded application. I have an appreciation for the size of that endeavor, but Autodesk wasn't blind-sided yesterday by this entire multiple CPU game, and I'd certainly like to see signs of life within the Revit dev team.

Anyhow, if Revit tops out at 27% of a quad-core xeon workstation, or 52% of dual core machine, I'd be hard pressed to call that a multi-threaded application, even if it does have delusions of grandeur. We all know about see-saw and setting the processor affinity, but that's like putting a band-aid on cancer.

Andy, after watching the way many single-threaded applications perform inside Windows XP, their default behavior is to load balance across two processors, but never utilizing more than 50% of each core.

To borrow some unix terminology, the single threaded app is "seeing" 100% when in fact a dual core can hit 200%, a quad core 400% and so on.


Ok, back to work.