1) Message boards : LHC@home Science : LHC @ Home on Playstation 3 (Message 20596)
Posted 2 Oct 2008 by Profile Chrulle
Post:
Another problem with the graphics cards/ps3 approach is that the cards are extremely fast single precision machines. Sixtrack however requires double precision. So the speed up is not as big. Another problem is with rounding errors. Sixtrack is very succeptible to incorrect rounding of floating point numbers. It took ages to work out the differences in the intel and amd architectures. It would be a lot of work to be certain that the GPU chips calculate correctly. Thirdly SixTrack as far as i remember relies on a lot of complex floating point math (sin/cos/exp/log) another area where the speed up of the graphics cards are not as impressive as when you can do simple vector operations.

Cheers,
Chrulle
Ex-LHCatHome developer
2) Message boards : Number crunching : New server: report broken links etc here (Message 14931)
Posted 1 Oct 2006 by Profile Chrulle
Post:

Finally, congrats to everyone for the success of the move. OK OK there were some issues, but I've seen a lot more issues when migrating servers. Well done everyone, and cunningplan to do the move when Chrulle was back in town ;-)


Sadly I flew back to Denmark this morning. But, I thought I would take one last look at the server before starting work tomorrow. The links should be fixed.

Do not expect too much support as there is officially no admin. All work on the server is done by volunteers in their spare time at the moment. This will soon change as the server is migrated to queen marys in england.

At the conference I ran into the guy who is going to take over the forums, and he is a really nice bloke. So you guys be nice to him. :-)

cheers,
3) Message boards : Number crunching : Garfield is coming.... (Message 14907)
Posted 29 Sep 2006 by Profile Chrulle
Post:

Looks like they're not yet up'n'running, though..

Here's the last work request log my client mad to L@H some seconds ago

29/09/2006 16.23.53|lhcathome|Sending scheduler request to http://lhcathome.cern.ch/lhcathome_cgi/cgi
29/09/2006 16.23.53|lhcathome|Reason: Requested by user
29/09/2006 16.23.53|lhcathome|Requesting 1728 seconds of new work
29/09/2006 16.23.58|lhcathome|Scheduler request succeeded
29/09/2006 16.23.58|lhcathome|Message from server: Server can't open log file (../log_boincsrv02/cgi.log)
29/09/2006 16.23.58|lhcathome|Project is down


That issue should now be fixed. Let me know

cheers


4) Message boards : Number crunching : LHC@home Alpha petition (Message 14887)
Posted 28 Sep 2006 by Profile Chrulle
Post:
The alpha-server is still running. But it is hosted on the same machine as the old lhc@home. So when the DNS record for lhc@home was changed alpha became unavailable.
I do not know what the plans are for the future though.

The workunits on alpha has not been important since the very beginning of lhc@home. It is simply the same study run a 100 times. So that we would always have work there.
Alpha was simply kept alive to test updates to webpages, daemons, setup and sixtrack, before they were moved to the main server, thus exposing as few people to the transition problems as possible.

Whether this will be relevant in the future i do not know. Especially when there is no regular admin. We barely have time to work on one system.

cheers,
5) Message boards : Number crunching : /stats/ empty (Message 14883)
Posted 28 Sep 2006 by Profile Chrulle
Post:
I tried to fix the problem. Stats should be online within 24 hours.

Cheers,
6) Message boards : Number crunching : Server Status (Message 14882)
Posted 28 Sep 2006 by Profile Chrulle
Post:
Hi everyone,

I am in town for a conference and helped out a bit.

I have put up the old server status. The XML stats dump should also be available after db_dump runs tonight. A news item on status of the project is forthcoming (by tomorrow latest).

Cheers,
Chrulle

7) Message boards : Cafe LHC : Anyone have some good song selections to share? (Message 14662)
Posted 19 Sep 2006 by Profile Chrulle
Post:
Ahoy, ye landlubbers.

In 'onor of talk like a pirate(viking) day, here be some fine sea shanties for ye:

Emmerson lake and palmer - Pirates
Henry wood - fantasia on british sea songs
Wagner - The Flying Dutchman
PRESS PLAY ON TAPE - Monkey Island
Traditional - Eh Ukhnem (Song of the Volga Boatmen)
(viking)
Jethro Tull - Broadsword
Led Zeppelin - Immigrant Song

you probably have to be danish to know these last ones:

Skatteøen (Treasure Island the musical)
(viking)
Shu-bi-dua - røde i staterne

Cap'n Chrulle of the good ship Red Herring
8) Message boards : Number crunching : LHC@home/CERN. Where Is Our Support! (Message 14169)
Posted 24 Jun 2006 by Profile Chrulle
Post:

Midwinter here...but what the hey! LHC is back! You the man Chrulle.

I'm willing to use a few cycles helping on testing of Garfield if you want.


Well, that is not up to me, but i will let you know when i hear anything more about garfield.
9) Message boards : Number crunching : LHC@home/CERN. Where Is Our Support! (Message 14167)
Posted 24 Jun 2006 by Profile Chrulle
Post:
Glædelig Sankt Hans to everyone. (happy midsummer)

I think the server should be running ok again, but i am a bit tired having been up all night burning as much forest as i could get my hands on, as my scandinavian heritage bids me. :-)

Some news: The server will probably be moved to a new machine in the beginning of august. I will lend a hand on my way through switzerland on my summer holliday. I might have time to look into some of the other issues, but i cannot promise it, since my new job might require me to do other work at CERN.

A big problem with the linking of Garfield on windows has been solved. So it might soon be ready for deployment on the public lhc@home.

cheers,
Chrulle
10) Message boards : Number crunching : Server problems (Message 13661)
Posted 18 May 2006 by Profile Chrulle
Post:
And he still is. At least until i get a job. ;-)

I have made a quick fix. Please check whether the system works again. Some credit and jobs have probably been lost, since i do not have the time to trawl through the backups.
11) Message boards : Number crunching : team emaillist not available in xml? (Message 13653)
Posted 17 May 2006 by Profile Chrulle
Post:
I updated the webpages just before i left, but as that was in late march too, we might just have missed the feature.

You could try to get someone to check whether it works on alpha. I think it is running a slightly newer version of the web pages.
12) Message boards : Number crunching : Server problems (Message 13652)
Posted 17 May 2006 by Profile Chrulle
Post:
Hi everyone,

I think the server has had an power outtage and that the DB has chrashed. At least that what it looks like to me. I will contact the Cern people to tell them. I might be able to guide them through a quick fix.
But for the time being you should probably choose "no new work" as it is very doubtful any work issued in the meantime will be registered in the DB. (i.e. it is lost. ) At least until someone can take the scheduler offline.

Cheers,
Chrulle
13) Message boards : Number crunching : Are we dead in the water? (Message 13585)
Posted 12 May 2006 by Profile Chrulle
Post:
I am back in denmark writing job applications, so i will probably check in from time to time. At least until i get a job. :-)
14) Message boards : Number crunching : LHC@home Alpha? (Message 13570)
Posted 11 May 2006 by Profile Chrulle
Post:
The alpha is as the names implies an alpha project. I used it to test updates and newer versions of sixtrack, before moving them to the main server. It is not important that the work there gets "chrunched" it is only there so we can test the results of new app versions.

I guess it is also the first place they will try out the garfield application once it is done. It has run on the cern internal boinc system and that worked. I think. I can tell you more once i see the meeting minutes.
15) Message boards : Number crunching : Are we dead in the water? (Message 13569)
Posted 11 May 2006 by Profile Chrulle
Post:
It is not that the admin do not care, but very often they know that there are new WU exactly the same way you do. By the number going up on the frontpage. The submission system is completely automated and the physicist that is submitting most of the work is in Canada. So even if he remembers to send an email saying he is putting up more work, the admins will probably have gone home. You should also remember that there is no full time admin at the moment.

But summer is soon here, so a bunch of summerstudents will be arriving soon. I am sure one of them will be put to work on the Boinc system, and will have some spare time to do some sys-admining.


16) Message boards : Number crunching : Are we dead in the water? (Message 13537)
Posted 9 May 2006 by Profile Chrulle
Post:
There is going to be a BOINC meeting this afternoon. Discussing the status of the different application and the work situation. Afterwards Ben might give you a summary of what is happening and otherwise I will try to extract a summary from the minutes.

17) Message boards : Number crunching : Request for database cleanup (Message 13528)
Posted 8 May 2006 by Profile Chrulle
Post:
It's unclear whether we have an admin on this project at present.


When i left, there was talk about a new spanish ph.d coming to replace me. But i have not heard anything more than that.


Other names I have seen associated with the technical background either haven't been seen for a long time, or have no involvement beyond the application development role, or both


All the people that have worked as sys admins through time has gone back to their studies. Jakob, Karl, Kalle and Markku all left to finish their studies, as did I. I returned and worked as a sysadmin for a year, but I am back in Denmark now enjoying the unseasonably warm weather and writing job applications.

The sys admin job has now been transferred to Ignacio Reguero and Phil Defert. Phil is working on automating the installation of a boinc server(so it is as simple as an rpm package), this makes it a lot easier to integrate the two new servers we got in the cern computer centres. Ignacio is mainly working on porting the new applications to lhc@home. Furthermore lhc@home is only a small part of their jobs. I have promised that I will be available if they have any technical question or need a few hours help with something I can guide them through remotely.

So you should not expect any major work being undertaken for the moment. Dave Anderson has also just released a request that people update the server software as soon as possible. I did an update just before I left so some of the features are already there. So I would guess they are mainly working on this.

2) There are still a couple hundred host records that are mangled from the upgrade that went bad and corrupted all the data in the host table. This is creating all kinds of trouble for some of the features I would like to implement on my stats site.


Couldn't you make a list of those hosts' id numbers and then use that list to discard those records from your stats program? You could also post that list here that would make the job of removing/fixing the records a lot easier for any coming admin.

cheers,
Chrulle

18) Message boards : Number crunching : I think we should restrict work units (Message 13423)
Posted 21 Apr 2006 by Profile Chrulle
Post:


Do we know that that is still in use? I assume it is


Greetings from the States.

I believe it is still in use. I do not think they have changed anything since i left.


My idea was to use differential deadlining *within* a WU - later results in the same WU would have shorter deadlines than the earlier ones - in contrast to Chrulle's which basically set a deadlines that vary between WU, but remain the same length for each result within a given WU.


That might be a good idea. Another good idea would be to give such result a higher priority. So that we are sure they are given out as fast as possible, instead of waiting in the queue.

cheers,
Chrulle
19) Message boards : Number crunching : Is the user base/project participants growing a bit too large, for our server? (Message 13170)
Posted 29 Mar 2006 by Profile Chrulle
Post:
Good luck Chrulle, we'll all miss you.

Are you going somewhere else to set up another BOINC project...? =D


Thanks,

I am now officially an ex-lhc@home developer, although i will probably lend a helping hand if something goes horribly wrong. I will spend a couple of weeks in Denmark fixing all the paper work of moving back here. Then i will go on vacation/job hunting in california.

I have some opportunities continuing to do Boinc projects. I might join africa@home for example.

Thanks for all your support of LHC@home. It has really helped the accelerator people. It looks like there is a possibility of other programs (Garfield a.o.) running on lhc@home next to SixTrack. This will help mitigate the intermittent work problem.
20) Message boards : Number crunching : php upgrade on alpha (Message 13096)
Posted 21 Mar 2006 by Profile Chrulle
Post:
we have upgraded the php files on the alpha site. If all alpha testers could please have a look, before we also upgrade here.

cheers,
Chrulle


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