Message boards : Number crunching : Mixture of 32Bit and 64Bit tasks
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Message 26541 - Posted: 24 May 2014, 12:32:15 UTC
Last modified: 24 May 2014, 12:38:28 UTC

Apologies in advance is this is an old question, but why are some tasks 32Bit and some 64Bit ? Is my PC assigned a 'random' selection comprising tasks for both CPU architectures ?

If there's an advantage in running 64Bit tasks on a 64Bit PC, is there a way that my account will only get assigned 64Bit tasks?
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Toby Broom
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Message 26543 - Posted: 24 May 2014, 13:03:09 UTC

As you can see in your screen shot, the exe is called win64 but you can see (32bit) at the end of all of them, all the LHC exe's are 32bit.

Since you can get x64 boinc software I think the project have to offer an x64 version even if it's not actually x64.
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Message 26544 - Posted: 24 May 2014, 13:39:49 UTC - in response to Message 26543.  

All our executables are 32-bit indeed. We just give them a different
name for 64-bit machines. Why? Because we have not (yet) verified
the numerical correctness of 64-bit executables. This implies using
a 64-bit version of crlibm, and running many many tests. Since the
performance is the same (in fact even a bit faster on 32-bit) it is
not a priority until other stability issues are solved. While in theory
there should be NO numerical differences the sad fact is that
different compiler versions are involved and we have had some
very bad experience. I am hoping to publish all this "soon" but right
now I say hello from the CERN 60th Anniversary Open Days. Eric.

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Message 26548 - Posted: 25 May 2014, 10:13:53 UTC

Thanks Toby - yes, I noticed after posting that they all state (32 bit), and should really have delved into Task Manager a bit more, as you can choose to display the 'Platform' column in the Details tab as below:



And thanks very much Eric - it's good to know I'm running Sixtrack in the most optimum format currently available. It might also help if I concentrate on tasks related to 'proton beam stability', and not 'pings from ET', but I'm sure you don't mind a mixture of LHC and SETI ;)

Good luck with the 60th anniversary celebrations - I wish I was there, but my kids are way too young to be allowed in. Fortunately there is a local exhibition at Manchester that I will take them too: http://mosi.org.uk/whats-on/collider
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Message 26549 - Posted: 25 May 2014, 10:39:01 UTC - in response to Message 26548.  

Hi Toby; the next performance improvement will be AVX support.
Colleagues are also working on GPU but that is a major change
probably requiring many more particles per WU.

Yesterday was great; I was at the LHCb experiment and even managed
to go 100m down and see the detector, but not the beam pipe or the
tunnel. The weather gods were kind and we had quite a few visitors
though not as many as last year for the "Portes Ouvertes". Probably
the last chance to visit for quite a few years as the LHC startup
should begin in a few months. The DG paid a flying visit. He is a strong
believer in outreach but I didn't get a chance to thank him for saving
LHC@home when he included it in a presentation at the Frankfurt Book
Fair in 2012.
Regards. Eric.
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Message 26555 - Posted: 25 May 2014, 16:25:10 UTC

Seems like AVX/2 will give a good boost to the app as it's the sort of calcs that AVX is designed for.

I'm sure GPU is a ton of work especially when you think about the mathematical equivalence that you strive for.

Sounds great I tried to visit when I was in Switzerland earlier in the year but the tours book up very far in advance I found out! Next time :)
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Message 26556 - Posted: 25 May 2014, 16:29:19 UTC - in response to Message 26548.  
Last modified: 25 May 2014, 16:29:31 UTC

Ben, every project is happy that you contribute what you can to there efforts.

It's up to you to decide which project your involved in and how much you contribute to each one.

I've contributed to 10 different project in various amounts :)
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Message 26557 - Posted: 25 May 2014, 20:53:20 UTC - in response to Message 26556.  

Thanks Toby. I was lucky enough to get a personal tour of the site when I came to visit a work colleague about 5 years ago, but obviously had to stay at the surface level. I bet more people have climbed Everest than visited the detectors ;) The visitor's facilities are excellent anyhow.

I was happy enough just looking down the viewing shafts and took loads of photos, but you just can't judge the physical scale looking down:



Anyway, I've gone way off topic here ;)
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Message 26559 - Posted: 26 May 2014, 5:21:02 UTC


Doesn't every member that started here in 2004 with over 980,000 credits get a free trip to Cern and tour of the LHC?




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Message 26560 - Posted: 26 May 2014, 5:48:47 UTC - in response to Message 26555.  

Well, as for GPU, the numerical business I am pretty sure I have
solved but need to test. If we can fit the main tracking loop into
the GPU, which has many smaller loops inside, BINGO. We only need
to write the small "checkpoint" data every so many turns back to
the host. However right now we have one binary file for every
pair of particles, and using a lot of particles (for GPU performance)
is impractical.

I am a guide, and next time you are in Switzerland, I can show you
round but I won't be able to take you 100m underground as the LHC
is scheduled for restart. Eric.

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Message 26564 - Posted: 26 May 2014, 13:11:57 UTC - in response to Message 26559.  

Magic I think the trips are free they're just very popular as you can imagine.
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Message 26565 - Posted: 26 May 2014, 13:16:06 UTC - in response to Message 26560.  

Sounds like you need a lot of refactoring in the code to support the GPU, now you can run OpenCL on Intel GPU's too, that should bring a lot of extra computing power to the project. I have my GTX titan ready for the project.
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Message 26566 - Posted: 26 May 2014, 18:53:02 UTC - in response to Message 26564.  

Actually what I was hoping for Toby is a free flight for 2 (have to bring the wife) from Seattle and free hotel.....ok it was just a dream

But of course I would want the tour by Eric so maybe you can get that free vacation too !


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Message 26576 - Posted: 28 May 2014, 3:01:18 UTC

That would be the best BOINC reward I every heard of :)

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Message 26579 - Posted: 28 May 2014, 4:48:34 UTC - in response to Message 26576.  
Last modified: 28 May 2014, 4:49:47 UTC

That would be the best BOINC reward I every heard of :)




Yes it would be better than an Einstein Certificate from the Max Planck

(ok don't tell anyone I said that )


But it does seem fair to me since I have been doing this daily since the Seti Classic days in 1999.........man I am getting to be an old timer.

Then Eric could let me pick another Boinc member to make that trip so that would have to be you since we both started over at T4T basically the same day and are here every day.........man hard to believe I have been on this project for 10 years now

And you have more hosts here than I do since mine are all GPU mad scientists @ the Einstein project.

You know you have to be interested in the LHC when we do this for hardly any of those *credits* (compared to those BRP PAS- GPU tasks)
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