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Mechanica: limiting (critical) hardware

JonathanHodgson
11-Garnet

Mechanica: limiting (critical) hardware

I'm wondering what the bottleneck is when running Mechanica analysis, hardware-wise.

We're currently running a large analysis on a 6 GB, quad-core machine. All the temporary files and results are going to the local hard disk, so there shouldn't be any significant network access (and the Task Manager graphs shows none).

Although Mechanica has recognised four cores (and occasionally uses them, getting more than 25% CPU usage), most of the time it's only at 5-10% CPU.

What's it waiting for? What hardware would increase the speed for these analyses? Do we need a fast RAID hard disk set-up, or faster memory, or more memory, or what?


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47 REPLIES 47

Apologies if this is a stupid question, and I'm just revealing my ignorance of Windoze memory management, but: why doesn't Mechanica use all the available memory before it starts spilling onto disk?

My PC reports 3.25 GB of installed memory, and generally runs around 1 GB in use (including Pro/E) according to Task Manager. My current Mechanica run typically pushes the "in use" up to about 1.7 GB (so ~700 MB of msengine.exe), and then starts using an additional 1+ GB on disk - why isn't it going up to ~3 GB of RAM first?

A pragmatic update for reference, for anyone else who's lurking on this discussion:

Regardless of the theory above about the matrix size, and optimising the memory allocation size, it appears that Mechanica essentially uses just over twice the value entered, in total.

So, on my old 32 bit machine a value of 896 MB seemed to be the maximum, and gave the fastest runs at around 2 GB used. 1024 MB caused it to crash.

On my new, 6 GB 64 bit machine, a setting of 2048 Mb seem to allow Mechanica to use about 4.5-5.0 GB (leaving 1 GB for Windoze and Pro/E); 2560 MB (2.5 GB) can just start it using the Windows swapfile and is therefore too much.

So, the old guidance of "set it to about half your available RAM" is still more-or-less correct!

.... and what about mechanica lite?

How do you set up the parameters, like solram there?

346gnu
12-Amethyst
(To:anagnost)

Hello Vassilis,

Look in the results folder 'myanalysis' in your set working directory and read the 'myanalysis.rpt' file. At the bottom it tells you about the ram allocated to the block solver.

Just had a bit of a play in WF5 (creo). The config option sim_solver_memory_allocation appears to be disabled for Mechanica lite; the 128Mb solram allocation hardwired.

Also just noticed that with the arrival of 'hard points' for mesh seeding (functionality not in lite), simple datum point seeding no longer helps improve the mesh in lite. Simple datum point seeding did work when lite first appeared.

Mechanica lite is very limited.

Great conversation here, very pertinent to what I'm dealing with right now. We're looking at getting a new system for our main Mechanica user to move him from a dual core XP 32 bit system with 4 GB of RAM to a quad core 2.8GHz Core i7 with 12 GB RAM running Win7 64 bit. A question that has come up several times in the past for us is the idea of having a central computer that does the number crunching for all of our FEA applications (Mechanica, CFDesign, Maxwell). Build it with multiple quad core CPUs at 3 Ghz, throw 48 GB of RAM into it and run Win7 64 bit with the latest version of each application. Both CFDesign and Maxwell have the ability to remote solve built in. Simply a couple of configuration steps and the user selects that computer as the "solver", it uses that computer to do the work while providing a progress / status feedback on their desktop (CFDesign will even send you a text message or email to let you know it's done). This allows them to start work on building their next analysis, do work in Word etc without having a crippled system due to the solution hogging their local compute resources. As far as I know, Mechanica does not have a simple, built-in remote solve capability. Is this correct? I can build the analysis locally, but I'd have to copy the setup to the remote computer, open Mechanica on that remote computer and run it there via a remote desktop (or just do the whole thing remotely). If Mechanica does have the ability to remote solve, how do I set it up? If it does not, are there plans to implement that capability?

Thanks.

Erik C. Gifford

Hi Eric,

You've accurately summarized the current Mechanica functionality. Mechanica does not yet have a simple, built-in remote solve capability. The closest existing functionality to what you want is the Run > Batch command. With it, you can create a study directory and a mecbatch.bat file that you can then copy to a compute server, and then use Microsoft Remote Desktop and a Command Prompt to run the analysis via the mecbatch.bat command. (See the online help for more details.)

Starting in Creo 1.0, you will be able to send any Mechanica analysis or design study to a remote compute server using the existing Distributed Pro/BATCH functionality.

Regards,

Tad Doxsee

346gnu
12-Amethyst
(To:TadDoxsee)

Tad,

A list of up and coming functionality now would be really really helpful. This sort of information drives a company's investment decisions.

I have added this 'remote solve facility' to my incomplete list of whats in CREO1.0 for simulation users. (we currently copy and remote desktop).

Bye for now

egifford
3-Visitor
(To:346gnu)

Charles makes a good point. The internal meeting I had yesterday regarding Mechanica, its capabilities, time to complete analysis etc was spurred by a just-out-of-college engineer saying he thinks we need to dump Mechanica and go to Ansys. Our current primary Mechanica user used to do FEA using Ansys at a prior job, so "ease of use" etc. isn't much of an argument. What it comes down to is capabilities of the software, where it's going in the future, the cost of any change, the fact we have so much already invested in Mechanica and that we use Pro/E as our primary CAD application. I don't see us making that shift in FEA packages, but, it sure would be nice to have some sort of roadmap from PTC regarding what they are working on in the analysis package even if that document comes with the standard "plans may change" legal statement on the bottom.

Tad - thanks for mentioning the remote solve capability to be introduced in Creo 1, with that implemented the solver computer concept potentially becomes an easier sell.

Charles - the computer configuration you mentioned earlier, is that your desktop or the remote computer you solve on?

Erik

346gnu
12-Amethyst
(To:egifford)

Erik,

The latest note on this thread reminded me I did not answer your question.

Mechanica is installed on the client and a license server. The license server is also a number cruncher and is physically on the next desk.

The models (batch files/directory) are simply copied from a client machine across the network. The chair is swivelled round and the batch file double clic ked.

Whilst msengine is busy we can still use the UI to review results and prep other models (unlike Ansys unless you have a license to enable you to use the solver and prep/post separately)

Disappointingly uncomplicated?

ttfn

Charles

egifford
3-Visitor
(To:346gnu)

Charles,

Thanks for the information. We have a number-cruncher in place now that can be accessed by all our FEA applications. For Mechanica we're doing pretty much what you describe except the user is connecting via a remote desktop from his regular workstation to the solver to launch the solve. I'm still looking forward to the "built in" remote capability, as is available in other applications we use. I've been tinkering with Creo 1.0 from the CAD side, I'll have to see what's been implmented for Mechanica.

For anyone that hasn't tried a setup similar to this and does sufficient FEA work, it's pretty easy to justify. You don't need a Cray to see the performance boost & half the benefit is the fact that the user's local PC isn't crippled while running a solution. In many cases they can be building the next problem and depending on the software, be kicking it into a queue to run next. Unlike giving one user a new, high-end computer, this effectively upgraded everyone.

Erik

In the Run Status box > Checkpoints tab, there is this info:

"Minimum recommended solram for direct solver: ___ "

What units is the reported number in -- MB or GB?

The units for the reported number are MB.

Tad,

Does Creo Simulation 1.0 support Intel virtual workstation clustering? Are there plans to support it in the future? The idea of having a seperate network that shares CPU cores and memory across many seperate workstations that are not having all of their memory or cores used could help speed things up. (no uploading to a remote server cluster)
http://www.deskeng.com/articles/aabbyg.htm

Just thinking out loud,

Don Anderson

Thanks,
Don Anderson
No time Like the Present!

Hi Don,

Creo Simulate does not yet support Intel virtual workstation clustering and we do not have any specific plans to do so in the near future. Thanks a lot for the link to Desktop Engineering article and for sharing your "out loud" thoughts. It looks like an intriguing way to share unused CPU cycles.

Tad Doxsee

PTC

Erik brought up Ansys so I'll share what I run into with Ansys albeit way late past Erik's post.

Ansys' licensing will give you only 2 CPU cores. That's right, Ansys counts a core as a CPU. So if you have a 4-core computer on a single socket, Ansys will only allow you to use 2 cores. To leverage more CPU cores you have to buy their HPC licenses. This is where it gets even more ridiculous, for solve session independence you can buy per CPU core and it's espensive, like $3500 per. Their HPC packs come in 8-CPU core packs which are tied to an individual solve so cannot be shared to other machines while in use, and that pack is about $22,000.

Why companies count cores now when multi-core CPUs are norm is beyond me and to be so outrageous is ridiculous.

I haven't seen if Creo Simulate has the same model, but I certainly hope it does not. Distributed computing is one thing to use CPU cores over the network but for solves based on a local machine the software should leverage all available cores, and not extort me with insane prices to do so.

Jason,

I agree that sounds pretty stupid!

With Mechanica (and Pro/E more generally) the issue is not licensing, but coding. Mechanica will happily use up to 64 cores (I believe), but it only does so for certain parts of certain types of analysis run. Therefore, those parts may run quickly, but the elapsed time is dominated by work which is still only carried out in a single thread. Pro/E (sorry, Creo) for the most part is purely single-threaded.

I recognise that there are significant programming challenges in using multiple threads efficiently; I'm just saying how it is currently...

I think Ansys does that because they can. "You want Ansys, ok, it's $$. Oh, and you also want it to run as fast as your computer can? Well in that case, it's $$$." These kind of marketing strategies are unfortunately common for the 1 or 2 products that are in the highest demand in their segment. Yes, it's inept engineering, and more reason to use Creo.

Below are the current hardware solutions I've found to speed up Creo at low cost, oriented towards both single and multi threads, but not HT:

- A 3570k cpu with a good air cooler, overclocked to ~4.6 GHz. Ivy Bridge can go faster but the disads increase rapidly. ~$300

- Max RAM -- the 3570k + Z77 can address 32 GB. Non-ECC seems to be fine at 32. ~$150

- Fast 128 GB SSD for writes (e.g., Samsung). ~$150

For larger models, there's the Sandy Bridge E that can address 64 GB, but the performance/price ratio is lower.

Crazy the timing of Jason resurrecting this discussion. We're again looking at Ansys (Ansys Professional NLT to be specific) because our primary FEA guy (the one I mentioned before that came from an Ansys house) says he needs it to efficiently do a simulation of a thermal cycle test on one of our assemblies. Basically time based hot - cold cycling to determine the mechanical effect on the parts. Claims Mechanica can't do it, or at least as easily / well as Ansys. So again, you're in the $25k range to get started and as Jason described, if you want to make use of the cores available to you on your PC or remote number cruncher, well, that costs extra...not talking an HPC cluster or anything, just let me use the cores available on the one PC. Cha-ching.

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