[CP2K:584] Re: cp2k chooses unsupported FFT grids

[Teodoro Laino]

Ciao Axel,

I found the problem (no need to send the input file). Let me just  
talk with Juerg (it's a bug introduced with the commit on the 6th  
round of pw_grid) in few hours and we will commit a patch.

Thanks!
Teo

On 15 Jan 2008, at 19:56, Axel wrote:

>
>
>
> On Jan 15, 6:35 pm, Juerg Hutter <hut... at pci.uzh.ch> wrote:
>> Hi Axel
>>
>> do I get it right:
>> CP2K would like to use 100, but because of the FFT length
>> table (see fftessl_lib.F) is forced to use 110. However,
>> your ESSL library complains that 110 is not a valid transform length.
>
> hello juerg,
>
> no. cp2k tries to use 100, but ESSL tells it to not use it
> and then suggests to use 110 instead.
>
> my first post was wrong. i misread the error message.
>
> it looks as if the get_length() subroutine is not called.
> i just added a print statement there and it does not show up.
> hmm...
>
> cheers,
>    axel.
>
>
>
>>
>> The table in fftessl_lib.F was copied from the ESSL manual.
>>
>> seehttp://publib.boulder.ibm.com/infocenter/clresctr/vxrx/ 
>> index.jsp?topi...
>>
>> where it says
>> Acceptable Lengths for the Transforms
>> Use the following formula to determine acceptable transform lengths:
>> n = (2h) (3i) (5j) (7k) (11m)    for n <= 37748736
>>
>> where:
>> h = 1, 2, ..., 25
>>   i = 0, 1, 2
>>   j, k, m = 0, 1
>>
>> so 110 is a valid length.
>> Do you have some very special version of ESSL?
>>
>> greetings
>>
>> Juerg
>>
>> ----------------------------------------------------------
>> Juerg Hutter                   Phone : ++41 44 635 4491
>> Physical Chemistry Institute   FAX   : ++41 44 635 6838
>> University of Zurich           E-mail: hut... at pci.uzh.ch
>> Winterthurerstrasse 190
>> CH-8057 Zurich, Switzerland
>> ----------------------------------------------------------
>>
>> On Tue, 15 Jan 2008, Axel wrote:
>>
>>> hi again,
>>
>>> small correction, after sprinkling a few debug prints into the  
>>> code i
>>> found,
>>> that the code picks a dimension of 100 and then suggests to use 110.
>>> my bad, i'm too used to fftw grids obviously. however, the main
>>> problem
>>> remains. 100 is not listed as supported by fftessl, so how come  
>>> it can
>>> select it?
>>> with -O2 i'm not exactly using an aggressive optimization...
>>
>>> puzzled,
>>>    axel.
>>
>>> On Jan 15, 4:49 pm, Axel <akoh... at gmail.com> wrote:
>>>> hi!
>>
>>>> i'm trying to run the 32 water quickstep benchmark on an IBM  
>>>> machine
>>>> with ESSL and the job stops with an error message, that a  
>>>> dimension of
>>>> 110 is not supported. while the error makes sense (essl does not
>>>> support
>>>> roots of 11, only fftw), shouldn't the code pick a compatible  
>>>> number?
>>>> i specified FFTESSL explicitely as preferred library and it is
>>>> compiled in
>>>> (or else, there would be no error)...
>>
>>>> any suggestions?
>>
>>>> cheers,
>>>>     axel.
> >