quartus_fit out of memory

[Altera_Forum]

When I use quartus II to compile my project, an Error occurs "quartus_fit out of memory ,used xxxx megabyte" . 

If I change the "Router Effort Multipler " from 3 to 1 , there's no Error(but the timming is not meet). Does anyone know what's the reason? Thanks   (the "memory" is not the FPGA memory, but PC memory)

[Altera_Forum]

add more memory to your PC? 

 What device are you trying to fit? Quartus requires a minimum of 3GB of ram for Arria 2 and Stratix 4 devices!

[Altera_Forum]

And note that 32-bit XP only uses 2G natively, even if you have more memory in the system. There is some option to get it up to 3Gb, called /3G, I think. 

I imagine you are right on the edge. Also note that the router effort multiplier does not get better timing on most designs. Only if it's hard to route and critical paths are forced to sub-optimal nets might it make a difference. For the most part I never use that option for timing closure. (On the flip-side, it doesn't hurt compile time much, so it generally doesn't hurt.)  Look at the peak memory use in your .flow.rpt. If you're right on the edge, I'd upgrade now. Who knows what other minor tweak starts pushing into out of memory errrors.

[Altera_Forum]

The device is stratix 3,and quartus is 8.0 32bit,win XP 32bit system. 

 I have a 3GB memory, but it seemed that only 2.99G can be detected.   When I used the option "/3GB" , I get "BlueScreen". My code only uses    40% resource of the FPGA, why it work so hard? Maybe it's because bad   coding style or something else? Is there a software which can limit the    memory used? Is it useful if I run quartus_fit on command line instead of    gui? Bottom-up increment compile?    Thanks

[Altera_Forum]

Once in the fitter, the memory usage is pretty independent of your coding style. (Naturally if you could code to use less physical resources, that would help, but I assume that's a general goal already.) Timing analysis is run during the fitter, and that can have an affect on memory footprint. There were some improvements with various releases of Quartus, so if you're on an old version, upgrading might help.  

The /3GB option is tricky. I have heard of a number of people successfully using it, but some people do have issues like the blue screen. It's really a MS issue at that point, but being limited to 2GB, I can certainly see a Stratix III going over that. My reference was the Stratix II 180, whereby that always seemed to be on the 2GB threshold, where some designs worked all the time and others went over the limit.  I would not try to design around it, as there are very few tricks to reduce memory footprint. (If you have extremely complex timing constraints in TimeQuest, it may help to re-organize them, but that's difficult to do since you don't know the internal data structures). Upgrading Quartus is one thought, but really it seems like a new machine is in order.