[Pw_forum] Comparison of 3.1.1 and 3.2 (cvs)

[Huiqun Zhou]

Stefano,

Here are the input file and a short script to run tests.

Huiqun

----- Original Message ----- 
From: "degironc" <degironc at sissa.it>
To: <pw_forum at pwscf.org>
Sent: Friday, November 24, 2006 4:39 PM
Subject: Re: [Pw_forum] Comparison of 3.1.1 and 3.2 (cvs)


> Dear Huiqun Zhou,
>    a couple of changes have been made in the mixing routine (mainly to 
> reduce its
> huge memory requirement in certain cases) from 3.1.1 to 3.2. These might 
> be the reason for  the different behaviors. Could you please post your 
> input so that we can try to fgure out what happened ?
>    Since every realization of an algorithm is the result of a compromise 
> between speed,
> memory use, work required to implement it, etc and since every compromise 
> will likely
> be more or less good depending on the particular application considered, a 
> comparison for
> different "typical" cases would also be useful in order to assess the 
> "average" performance
> (or loss of it) from 3.1.1 to 3.2
>    Thank you,
>         stefano
>
> Huiqun Zhou wrote:
>
>> Kostya,
>>
>> The number of SCF iterations is indeed the same regardless of the
>> number of CPU cores used for both versions. Furthermore, the process
>> of SCF convergence is precisely the same whatever we use 1, 2 or 4
>> CPU cores. This is true for both versions. And the final total energy 
>> found
>> by both version is the same. But, the behaviour of convergence of one
>> version compared to another is different if you watch the changes of
>> numbers after decimal point. It seems that the criteria of convergence of
>> each version are different.
>>
>> I have created three graphs for the pattern of convergence on 1, 2, 4 
>> cores
>> (but they are tottally the same as mentioned above). Each graph contains
>> a comparison of patterns of the two versions. Please let me know where
>> I can post the graphs, each of which is about 55KB, as I don't think this
>> forum permit posting a file with such large size.
>>
>> Here I first include the six data files extracted from the results. you 
>> can
>> plot the graph yourself, too.
>>
>> Please give me a pointer what kind of benchmarks you want me to run.
>> Do you think it's worth tring the same system with different type of run 
>> (relax, ...),
>> different method of diagonalization? Currently, all results I reported 
>> made use
>> of 'david' method for diagonalization.
>>
>> Regards,
>>
>> Huiqun
>>
>>
>> ----- Original Message ----- From: "Konstantin Kudin" 
>> <konstantin_kudin at yahoo.com>
>> To: <pw_forum at pwscf.org>
>> Sent: Friday, November 24, 2006 1:42 AM
>> Subject: Re: [Pw_forum] Comparison of 3.1.1 and 3.2 (cvs)
>>
>>
>>>
>>> --- Huiqun Zhou <hqzhou at nju.edu.cn> wrote:
>>>
>>>> (2) Version 3.1.1 is much faster than the cvs version as the former
>>>>   took only 13 scf iterations to reach convergence while the latter
>>>>   needed 16 iterations.
>>>
>>>
>>> Dear Huiqun,
>>>
>>> If the number of the SCF iterations is the same regardless of the
>>> number of cpus for both versions, then please post some kind of
>>> convergence pattern like for total energies. That would give developers
>>> a chance to evaluate if any of the recent changes might have caused
>>> this. Sometimes small numerical noise is a benign "feature", and
>>> sometimes it is a bug, so figuring out what is going on for your test
>>> would be useful.
>>>
>>> Also, perhaps you could try a different benchmark to see how things
>>> work there, if there are any differences found there as well.
>>>
>>> Kostya
>>>
>>>
>>>
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>
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