[FLASH-USERS] Question about grid size

[John ZuHone]

From a computational perspective, having blocks with that many zones is pretty impractical. FLASH’s performance is much better with far smaller sizes (such as 16x16). 

I’d recommend picking nblock[xy] in the parameter file such that when you multiply it by whatever you pick for -n[xy]b (something like 16 or 32) yields 512. It should be fairly easy that writes a setup that maps from the initial condition to that pattern of blocks.

> On May 24, 2017, at 12:56 PM, Jenks, Malia T. <mjenks at ou.edu> wrote:
> 
> Tomek,
> 
> Where does the 2000 come from?
> Maxblocks is auto set to 1000.
> 
> The point is I am reading in an external grid that is 512x512 and I want the FLASH grid to match it exactly  so that I can do a trivial map of the physical quantities.
> 
> I'm missing something.
> 
> Malia
> From: Jenks, Malia T.
> Sent: Wednesday, May 24, 2017 10:32:34 AM
> To: flash-users at flash.uchicago.edu
> Subject: Re: Question about grid size
>  
> Hmm, somehow Flash is statically allocating more than the Linux 2GB limit. I'm surprised that anything is statically allocated. 
> 
> I did a parallel compile but assuming (for debugging purposes) that I would just use 1 CPU. Thus, I set iProcs =1
> jProcs=1  and
> 
> setup -2d +cylindrical +usm -nxb=512 -nyb=512 -auto
> 
> Then at link time I get:
> 
> Burn.o: In function `burn':
> /home/mjenks/FLASH4.4/object/Burn.F90:107:(.text+0xe3): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_useburn_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:115:(.text+0x2ad): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_useshockburn_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:145:(.text+0x604): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_useshockburn_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:172:(.text+0x897): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_nucleartempmin_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:175:(.text+0x8bc): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_nucleartempmax_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:174:(.text+0x8dc): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_useshockburn_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:173:(.text+0x8f1): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_nucleardensmin_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:173:(.text+0x8f9): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_nucleardensmax_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn.F90:181:(.text+0x961): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_nuclearni56max_' defined in COMMON section in Burn_data.o
> Burn_computeDt.o: In function `burn_computedt':
> /home/mjenks/FLASH4.4/object/Burn_computeDt.F90:108:(.text+0x16): relocation truncated to fit: R_X86_64_PC32 against symbol `burn_data_mp_bn_useburn_' defined in COMMON section in Burn_data.o
> /home/mjenks/FLASH4.4/object/Burn_computeDt.F90:141:(.text+0x69): additional relocation overflows omitted from the output
> make: *** [flash4] Error 1
> 
> which means that I have > 2GB of static data see https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/268374 <https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/268374>
> 
> which shouldn't be happening. 
> 
> Ideas?
> 
> Malia
> relocation truncated to fit: R_X86_64_PC32 - Intel® Software <https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/268374>
> software.intel.com
> Hi, I'm trying to compile a big code that so far has been running fine.Now, we have surpassed the 2GB in statically allocated data limit. I knew that would bring us ...
> 
> 
> From: Jenks, Malia T.
> Sent: Tuesday, May 23, 2017 4:29:17 PM
> To: flash-users at flash.uchicago.edu
> Subject: Question about grid size
>  
> I tried to increase the number of cells in my 2d model to 512 by 512. It will not compile at this size and I get an error about static memory. Is there a way I can solve this?
> 
> Malia Jenks

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