[Radiance-general] New rtcontrib?

[Jack de Valpine]

Hey Greg,

Excellent. Many thanks for the quick summary. I had noticed the name 
change on a build from current head source I did on a new virtual 
machine a few weeks ago. Happily my scripts that I had put together 
based on the original rtcontrib seem to run fine.

Best,

-Jack

-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

On 8/10/2012 11:41 AM, Greg Ward wrote:
> Functionally, the rcontrib replacement of rtcontrib is meant to be identical.  The only real difference should be performance.  There is a minor exception to this, which is that rcontrib *requires* the -bn option when -b is anything but "0".  This was always good practice before, and now it is enforced.  All the options and behavior is otherwise the same.
>
> Under the hood, the code has changed dramatically.  Before, rtcontrib was a separate process that would call rtrace with either -oTW or -oTV options, generating a huge trace tree that would have to be interpreted by rtcontrib.  This was slow under the best of circumstances, and got much slower as rtrace processes were added using the -n option.  The rtcontrib process ended up being a major bottleneck.  The new code is a single program that forks copies of itself to do the ray-tracing, summing up contributions in each child process.  This avoids the inter-process communication, memory overhead, and aforementioned summation bottleneck of the original.  I have also added optimizations for when -c is greater than 1 by further batching summations in child processes and reducing communication overhead that way.  If you aren't getting linear speed-up with a particular scene and -n setting, increasing -c should get you there.
>
> We have done a fair amount of testing to where we feel pretty confident there are no major bugs in the new code, but feedback is welcome.  Lars and I are currently trying to track down some anomalies he's seeing in testing, but by the time of the workshop things should be sorted out if not sooner.
>
> Cheers,
> -Greg
>
>> From: "Guglielmetti, Robert" <Robert.Guglielmetti at nrel.gov>
>> Date: August 10, 2012 7:32:01 AM PDT
>>
>> Hi Jack,
>>
>> AFAIK, the only summary is the diff between the rtcontrib and rcontrib
>> manpages, and a blurb in the release notes. Greg and Andy can surely
>> provide more details...
>>
>>
>> Rob Guglielmetti
>>
>>
>> On 8/10/12 7:18 AM, "Jack de Valpine" <jedev at visarc.com> wrote:
>>
>>> Hi Rob, Lars and Marija,
>>>
>>> I will hop in on this and ask is there any summary or comparison of
>>> functionality between the two tools?
>>>
>>> Thanks,
>>>
>>> -Jack
>>>
>>>
>>> On 8/10/2012 9:12 AM, Guglielmetti, Robert wrote:
>>>> Hi all,
>>>>
>>>> Marija, yes, the new rcontrib is in the HEAD, and is available in the
>>>> latest NREL binaries. Lars, the symlink is only created by the makeall
>>>> script. If you use the NREL binaries, rtcontrib is really rtcontrib, and
>>>> rcontrib is rcontrib. Clear as mud, eh? Greg, you should have named
>>>> rcontrib "totally_different_coefficient_calculator". =)
>>>>
>>>> - Rob
>>>>
>>>> ________________________________________
>>>> From: Lars O. Grobe [grobe at gmx.net]
>>>> Sent: Friday, August 10, 2012 6:11 AM
>>>> To: Radiance general discussion
>>>> Subject: Re: [Radiance-general] New rtcontrib?
>>>>
>>>> Hi Marija!
>>>>> I suppose new version is available in HEAD source code version? Is it
>>>>> called 'rcontrib' or 'rtcontrib'?
>>>> The new one is rcontrib, but there is a symlink named rtcontrib pointing
>>>> to it, so you do not need to change your scripts.
>>>>
>>>> Cheers, Lars.
>>>>
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