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From: Brad Krane <brad.krane_at_gmail.com>

Date: Mon, 8 May 2006 02:03:58 -0400

I have been coming up to the same problem with Gadget2 now for a few

days now with out any real success. It seems that if I run a

non-periodic simulation long enough that one or more of the particles

leaves the PM which is usually fine at first but eventually Gadget is

unable to recover and the program halts with a 68687 error. I know

that one way to fix this problem is to increase the PMGRID size on

compile, but this seems to lead to two problems:

1. An exponential increase in memory use.

2. The particle will just leave the now larger mesh later in the

simulation anyway.

Is there anyway that I might be able to just kill the offending

particle completely from the simulation and thereby prevent the crash?

Would this approach lead to problems? Is there a better way that I am

not thinking about? Or should I just get a better computer? ;)

Thank you.

Here below is a sample of the output if that helps clarify my situation.

Begin Step 2, Time: 0.0437879, Redshift: 21.8373, Systemstep:

0.00107381, Dloga: 0.0248285

domain decomposition...

NTopleaves= 176

work-load balance=1 memory-balance=1

domain decomposition done.

begin Peano-Hilbert order...

Peano-Hilbert done.

Start force computation...

Starting non-periodic PM calculation (grid=0).

Particle Id=142373 on task=0 with coordinates

(-68861.4|-1927.9|-1800.34) lies outside PM mesh.

Stopping

In total 1 particles were outside allowed range.

Allowed region for isolated PM mesh (coarse):

(-68861.4|-68906.6|-68905.6) -> (68906.8|68861.6|68862.6)

ext=137768 totmeshsize=286880 meshsize=1120.63

Starting non-periodic PM calculation (grid=0).

done PM.

Tree construction.

Tree construction done.

Begin tree force.

tree is done.

force computation done.

type=1 dmean=510.503 asmth=1400.78 minmass=1.10779 a=0.0437879

sqrt(<p^2>)=6.81455 dlogmax=0.17174

type=2 dmean=496.112 asmth=1400.78 minmass=1.01672 a=0.0437879

sqrt(<p^2>)=4.92943 dlogmax=0.230724

type=3 dmean=185.921 asmth=1400.78 minmass=0.0535116 a=0.0437879

sqrt(<p^2>)=5.61213 dlogmax=0.0759471

displacement time constraint: 0.03 (0.03)

Begin Step 3, Time: 0.0448887, Redshift: 21.2773, Systemstep:

0.0011008, Dloga: 0.0248285

domain decomposition...

NTopleaves= 176

work-load balance=1 memory-balance=1

domain decomposition done.

begin Peano-Hilbert order...

Peano-Hilbert done.

Start force computation...

Starting non-periodic PM calculation (grid=0).

Particle Id=142373 on task=0 with coordinates

(-68871.7|-1927.62|-1803.53) lies outside PM mesh.

Stopping

In total 1 particles were outside allowed range.

Allowed region for isolated PM mesh (coarse):

(-68871.7|-68914.7|-68906.5) -> (68899.7|68856.7|68864.9)

ext=137771 totmeshsize=286887 meshsize=1120.65

Starting non-periodic PM calculation (grid=0).

Particle Id=142312 on task=0 with coordinates

(68899.7|-1661.64|1693.9) lies out side PM mesh.

Stopping

In total 1 particles were outside allowed range.

task 0: endrun called with an error level of 68687

Date: Mon, 8 May 2006 02:03:58 -0400

I have been coming up to the same problem with Gadget2 now for a few

days now with out any real success. It seems that if I run a

non-periodic simulation long enough that one or more of the particles

leaves the PM which is usually fine at first but eventually Gadget is

unable to recover and the program halts with a 68687 error. I know

that one way to fix this problem is to increase the PMGRID size on

compile, but this seems to lead to two problems:

1. An exponential increase in memory use.

2. The particle will just leave the now larger mesh later in the

simulation anyway.

Is there anyway that I might be able to just kill the offending

particle completely from the simulation and thereby prevent the crash?

Would this approach lead to problems? Is there a better way that I am

not thinking about? Or should I just get a better computer? ;)

Thank you.

Here below is a sample of the output if that helps clarify my situation.

Begin Step 2, Time: 0.0437879, Redshift: 21.8373, Systemstep:

0.00107381, Dloga: 0.0248285

domain decomposition...

NTopleaves= 176

work-load balance=1 memory-balance=1

domain decomposition done.

begin Peano-Hilbert order...

Peano-Hilbert done.

Start force computation...

Starting non-periodic PM calculation (grid=0).

Particle Id=142373 on task=0 with coordinates

(-68861.4|-1927.9|-1800.34) lies outside PM mesh.

Stopping

In total 1 particles were outside allowed range.

Allowed region for isolated PM mesh (coarse):

(-68861.4|-68906.6|-68905.6) -> (68906.8|68861.6|68862.6)

ext=137768 totmeshsize=286880 meshsize=1120.63

Starting non-periodic PM calculation (grid=0).

done PM.

Tree construction.

Tree construction done.

Begin tree force.

tree is done.

force computation done.

type=1 dmean=510.503 asmth=1400.78 minmass=1.10779 a=0.0437879

sqrt(<p^2>)=6.81455 dlogmax=0.17174

type=2 dmean=496.112 asmth=1400.78 minmass=1.01672 a=0.0437879

sqrt(<p^2>)=4.92943 dlogmax=0.230724

type=3 dmean=185.921 asmth=1400.78 minmass=0.0535116 a=0.0437879

sqrt(<p^2>)=5.61213 dlogmax=0.0759471

displacement time constraint: 0.03 (0.03)

Begin Step 3, Time: 0.0448887, Redshift: 21.2773, Systemstep:

0.0011008, Dloga: 0.0248285

domain decomposition...

NTopleaves= 176

work-load balance=1 memory-balance=1

domain decomposition done.

begin Peano-Hilbert order...

Peano-Hilbert done.

Start force computation...

Starting non-periodic PM calculation (grid=0).

Particle Id=142373 on task=0 with coordinates

(-68871.7|-1927.62|-1803.53) lies outside PM mesh.

Stopping

In total 1 particles were outside allowed range.

Allowed region for isolated PM mesh (coarse):

(-68871.7|-68914.7|-68906.5) -> (68899.7|68856.7|68864.9)

ext=137771 totmeshsize=286887 meshsize=1120.65

Starting non-periodic PM calculation (grid=0).

Particle Id=142312 on task=0 with coordinates

(68899.7|-1661.64|1693.9) lies out side PM mesh.

Stopping

In total 1 particles were outside allowed range.

task 0: endrun called with an error level of 68687

-- BradReceived on 2006-05-08 08:03:59

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