I mean — it’s safe — it won’t hurt anything except your wallet. But…I do not have guidance as to how much RAM you _should_ have, for any given system.

Unfortunately all of my systems tend to be a bit RAM-heavy…a developer system needs extra RAM to run the debugger and other code tools simultaneous to X-Plane, and the render farm needs memory per core for DSF generation, so I’ve had 12 GB in my Mac for a few years.

As no new posts have been made lately, progress surely is going on. Would it be a safe idea to purchase more RAM / install prior to beta or not, ie time frame and performance wise regarding new shipment of art assets?

Thanks.

Nope – we don’t benefit. Here’s why:
1. We basically don’t use 64-bit integer math at all. We just don’t have a use for it. So having native 64-bit integer ops isn’t a win. (If it was, we’d use mmx/sse more. 🙂
2. For floating point math, we assume we have SSE, so we get the same API no matter what. Most of the flight model is 32-bit floating point though – back in the day that’s all that was fast on x86 machines. It’s still that way because we don’t need 64 bits (except in the places we already use them) and going in and changing everything would be a lot of regression testing for no benefit.
3. The real key is what we spend time on. X-Plane is not bound on math – we are bound on L2 cache performance. Simply put, the CPU can do the ‘thinking’ we want it to do faster than the memory controller can feed it the next piece of data to think about. So having faster thinking is of literally no benefit — it means the CPU is bored more of the time.

The reason for this is: the work that the sim does is:
90% rendering engine – all of the ALU specific stuff is in the driver or sent to the GPU.
10% flight model – and of that, it’s 20% floating point, and 80% searching the scene graph for collisions.

Just not a lot of ALU bound stuff.

http://www.passmark.com/forum/showthread.php?3348-64bit-vs-32bit-benchmarks-amp-integer-maths-amp-PT8

Flight modelling too would require a lot of calculation. You’d think X-Plane would benefit more than most apps… Theoretically of course!

The following is comparing XP 32 with Windows Server 2003 64, but maybe it is the same with Windows 7 64!

http://www.passmark.com/forum/showthread.php?261-Comparing-64bit-and-32bit-CPU-benchmark-results

Surely some of your longitude and latitude calcs were using 64bit integers or floating point arithmetic…?

Wiht 10.20- it’s not out yet.

Thanks Ben. Will the 64-bit version of the SDK come out with 10.20 or is it around somewhere and I just haven’t found it?

Puffy, does HDR work for you on Mac OS? It crashes for me on 10.8.2 I believe. I sent in a bug report. I was planning on trying the Nvidia drivers to see if they work.

You have to port your 32-bit W7 plugin to 64 bits to have it work with the 64-bit version of 10.20.
You do not have to port your 32-bit W7 plugin to 64 bits to have it work with the 32-bit version of 10.20.

So if you do not port it, some users will run your plugin in 32 bits, and some will run the 64-bit sim (causing your plugin to not load), and some of those users will complain.