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Slow case loading on parallel fluent

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Old   December 20, 2011, 01:03
Default Slow case loading on parallel fluent
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Hi,

I am new to fluent. However, I just need to do some simple simulations so I am using a consumer PC. Recently I am running Fluent on a single PC i7-2600 with 12GB(4+4+2+2) memory. I plan to use the 4 cores (8 threads), the solver works as expected, but the case loading and writing are quite slow. I am not sure if these is any hardware limits for it. The case loading/writing works very smooth and fast in the serial mode. It has totally 55180 nodes in the case file and each computing node has about 5800 cells.

I appreciate if someone can point me out if there is any mistake.

Thanks,
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Old   December 20, 2011, 14:41
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Quote:
Originally Posted by jhome View Post
Hi,

I am new to fluent. However, I just need to do some simple simulations so I am using a consumer PC. Recently I am running Fluent on a single PC i7-2600 with 12GB(4+4+2+2) memory. I plan to use the 4 cores (8 threads), the solver works as expected, but the case loading and writing are quite slow. I am not sure if these is any hardware limits for it. The case loading/writing works very smooth and fast in the serial mode. It has totally 55180 nodes in the case file and each computing node has about 5800 cells.

I appreciate if someone can point me out if there is any mistake.

Thanks,
Hi jhome

First of all your pc has only 4 cores, you see 8 cores because of the hyperthreading. As cfd codes are effectice in filling up the computational power, it would be better to turn ht off and use just 4 cores.

The slow loading time could be caused by a slow hd or network, if you are accessing ddata somewhere else.
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Old   December 20, 2011, 15:02
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Thank you sail. I turned off the hyperthreading and the case loading is much faster than before. But it is still not as smooth as loading in serial mode. I am reading case file from hard disk, which is 7200rpm. Will this be a problem? However, my network is only 100mb Ethernet. Will it access network frequently during the case loading. I think it shall use shared memory.

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Originally Posted by sail View Post
Hi jhome

First of all your pc has only 4 cores, you see 8 cores because of the hyperthreading. As cfd codes are effectice in filling up the computational power, it would be better to turn ht off and use just 4 cores.

The slow loading time could be caused by a slow hd or network, if you are accessing ddata somewhere else.
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Old   December 21, 2011, 16:19
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Originally Posted by jhome View Post
Thank you sail. I turned off the hyperthreading and the case loading is much faster than before. But it is still not as smooth as loading in serial mode. I am reading case file from hard disk, which is 7200rpm. Will this be a problem? However, my network is only 100mb Ethernet. Will it access network frequently during the case loading. I think it shall use shared memory.
Parallel read/write is always slower in fluent. This is because it distributes mesh and solution to clients while reading. Only server does this job and clients does nothing for IO. There is a parallel IO mode which is superfast, but i don't remember how to turn on this.
Never use threading it always limits your processing power. Its good only for multi-threading applications like games
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