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 FasterCap and FastCap2
 memory in FasterCap
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IanRedman

2 Posts

Posted - Jan 17 2012 :  18:07:45  Show Profile  Reply with Quote
Is there a reason why Fastercap is limited to (a % of) 2Gb before it drops into out-of-core mode?
We have a PC with 16Gb of ram which it seems we can't make use of. Is there a way around this limitation?

Thanks,

Ian

Enrico

550 Posts

Posted - Jan 18 2012 :  22:59:08  Show Profile  Reply with Quote
You can control the out-of-core behavior of FasterCap with the following parameter available in the Run dialog:

'Out-of-core free memory to link memory condition (0 = don't go OOC) (-f)'

So setting this parameter to zero effectively prevents FasterCap from going OOC. You can also define different levels of memory occupation estimations over which FasterCap will switch to disk memory.

However, please mind that FasterCap, for maximum optimization, stores the links on the disk, while still using the internal memory for other activities (e.g. converging the matrix through the iterations via the GMRES algorithm). So you need to keep part of the memory available for these uses, i.e. go out-of-core as soon as the links occupy a fraction of the overall free memory; an average value is 1/5, which is the default.

One final note on the total memory available on your PC: please mind that in Windows 32bit versions, the total memory that can be allocated to a single task is 4Gb maximum, because this is the maximum value that can be addressed with 32 bits. Having more than 4Gb simply means that you can have more than one task using up to 4Gb, since this memory is made (virtually) private to the task; but still the max per task is 4Gb.

On its part, FasterCap for x64 has no 2G / 4G memory limit at all.

Kind Regards,
Enrico
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