[Developers] Steering checkpointing by wall time

[Erik Schnetter]

This is how many of the other parameters also work, for example  
checkpoint_every.  It disables checkpointing if set to -1, else sets  
the checkpointing interval.  Ditto for all other output interval  
parameters in the I/O thorns.

It's quite common to have an out-of-band value, for example strchr()  
returning a null pointer if the character cannot be found, or a light  
switch being a switch and a dimmer at the same time (instead of two  
separate controls).

-erik

On May 7, 2008, at 15:50:56, Allen Gabrielle wrote:

> In that case, I think you are asking the parameter to do two different
> things, and then should instead have two different parameters.
>
> On May 7, 2008, at 3:42 PM, Erik Schnetter wrote:
>
>> 0 is not a legal value.  We could make it legal, and then it would
>> mean to checkpoint as often as possible.
>>
>> I prefer -1 for this out-of-band value, since it is immediately
>> clear that -1 does something special.  It is not as clear that 0 has
>> a special meaning.
>>
>> On another note, using minutes as unit becomes impractical if the
>> time span becomes of the order of days.  People don't know offhand
>> how many minutes there are in a day.
>>
>> -erik
>>
>> On May 7, 2008, at 15:32:06, Allen Gabrielle wrote:
>>
>>> What happens if you checkpoint every 0 hours? (That is, can we  
>>> remove
>>> the -1 option
>>> to disable checkpointing if choosing 0 does this).
>>>
>>> On May 7, 2008, at 2:38 PM, Ian Hinder wrote:
>>>
>>>> Erik Schnetter wrote:
>>>>> I suggest to add a new parameter to CactusBase/IOUtil which
>>>>> checkpoints every so many wall clock hours.  This is often more
>>>>> convenient than choosing the checkpointing interval by iterations.
>>>>
>>>> This is a good idea.  Should it be hours, or minutes or seconds?  I
>>>> think the termination condition is done in minutes, which seems
>>>> reasonable to me.
>>>>
>>>>
>>>>>
>>>>> -erik
>>>>>
>>>>> Index: param.ccl
>>>>> = 
>>>>> ==================================================================
>>>>> RCS file: /cactusdevcvs/CactusBase/IOUtil/param.ccl,v
>>>>> retrieving revision 1.51
>>>>> diff -u -r1.51 param.ccl
>>>>> --- param.ccl	18 Apr 2007 16:00:12 -0000	1.51
>>>>> +++ param.ccl	7 May 2008 18:50:15 -0000
>>>>> @@ -142,6 +143,11 @@
>>>>> 1:* :: "Every so many iterations"
>>>>> -1:0 :: "Disable periodic checkpointing"
>>>>> } -1
>>>>> +REAL checkpoint_every_walltime_hours "How often to checkpoint"
>>>>> STEERABLE = ALWAYS
>>>>> +{
>>>>> +  (0:* :: "After so much walltime has passed"
>>>>> +  -1   :: "Disable periodic walltime checkpointing"
>>>>> +} -1
>>>>> BOOLEAN checkpoint_on_terminate "Checkpoint after last iteration"
>>>>> STEERABLE = ALWAYS
>>>>> {
>>>>> } "no"
>>>>>
>>>>
>>>>
>>>> -- 
>>>> Ian Hinder
>>>> hinder at gravity.psu.edu
>>>> http://www.gravity.psu.edu/~hinder
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>>>>
>>>
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>>
>>
>> -- 
>> Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/
>>
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>>
>>
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>
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-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/

My email is as private as my paper mail.  I therefore support encrypting
and signing email messages.  Get my PGP key from www.keyserver.net.



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