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Using probe lengthening time of run

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Old   July 29, 2008, 13:44
Default Hi all, I recently inserted
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Scott Ford
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Hi all,

I recently inserted a probe into my controlDict so that I could track the velocity of my flow at a specific point more precisely. Before inserting the probe, I could get 1 second of data simulation in about 10 hours of computer time. But since I have inserted the probe, I am now looking at the time frame of 1 second of simulation for about 150 hours of computer time. This is clearly unacceptable and not worth the cost of calculation. Has anybody else experienced a similar problem or is this just what the probe function must do? Can anybody get me back to the time frame i was looking at before? Thanks ahead of time.

Scott
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Old   July 30, 2008, 05:58
Default We use probes all the time and
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Eugene de Villiers
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We use probes all the time and have not experienced such a problem. My guess is it has something to do with disk access. What operating system are you running on?
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Old   July 30, 2008, 09:31
Default I'm using RedHat Enterprise Li
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Scott Ford
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I'm using RedHat Enterprise Linux 4.4
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Old   July 30, 2008, 10:55
Default Can you upgrade to 4.5? There
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Eugene de Villiers
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Can you upgrade to 4.5? There was a bug in NFS in one of the RHEL kernels, either 4.3 or 4.4, I'm not sure which, which causes the problems you are encountering.

We had a situation where the run would slow down massively after the first write to disk and it went away after the OS was upgraded.
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Old   July 30, 2008, 11:05
Default It would take several days for
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It would take several days for us to upgrade to 4.5, so its not likely. I do know of the problem you had with time increasing after your first write to disk and I know that was fixed with version 4.4. I guess I'll keep trying some stuff, however I'm still unsure what the root of the problem is. Thanks.

Scott
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