Welcome to MilkyWay@home

Posts by Eric Mendelsohn

1) Message boards : MilkyWay@home Science : Result of our work in M@H (Message 68850)
Posted 7 days ago by Eric Mendelsohn
Post:
I cannot speak for Separation, since I am not working on that project, but the current Nbody runs are attempting to determine the properties of the progenitor galaxy which turned into the Orphan Stream. The last set of runs, however, were inconclusive. The three runs we put up converged to two very different progenitor dwarf galaxies. At the moment, we have Nbody runs up to see if we find the same convergence problems when comparing to simulated data of a similar structure. We will most likely need more stellar data in order to precisely calculate the mass and structure of the progenitor dwarf galaxy using MilkyWay@home.

Thank you for taking interest in our research and for your support.

-Eric
2) Message boards : News : NewER runs for Milkyway_nbody (Message 68841)
Posted 11 days ago by Eric Mendelsohn
Post:
Hey all,

Sorry, there was a problem with the newest runs for nbody. I've taken them down and replaced them with these runs:
-de_nbody_06_06_2019_v176_40k__sim__1
-de_nbody_06_06_2019_v176_40k__sim__2
-de_nbody_06_06_2019_v176_40k__sim__3

I apologize for any inconvenience. Thank you once again for your support.
-Eric
3) Message boards : News : New runs for Milkyway_nbody (Message 68838)
Posted 12 days ago by Eric Mendelsohn
Post:
Hello all,

Just wanted to let you know that a new batch of runs for milkyway_nbody were just put on the server. The names of the runs are as follows:
-de_nbody_06_05_2019_v176_40k__sim__1
-de_nbody_06_05_2019_v176_40k__sim__2
-de_nbody_06_05_2019_v176_40k__sim__3

If you have any issues or questions about these runs, please let me know. Thank you all for your support.
-Eric
4) Questions and Answers : Unix/Linux : Running 3 tasks only (Message 68789)
Posted 21 days ago by Eric Mendelsohn
Post:
Since I've never done N-body, I am not sure what the app name for it is. Likely just nbody.

The app name for the Milky Way N-body simulator is "milkyway_nbody". Hope this helps.

-Eric
5) Message boards : News : [RESOLVED] Problems with Receiving Email for Resetting Passwords (Message 68774)
Posted 26 days ago by Eric Mendelsohn
Post:
Hello all,

It has come to my attention that there are some people who are having trouble resetting their passwords. More specifically when requesting a link to reset their password, the email with the link to change their password never arrives in their inbox or spam. At the moment, I have been able to reproduce this problem with gmail accounts and some temporary email accounts. So far, I've only been able to get my university email account to receive a password reset link. While I will continue to troubleshoot this issue, I humbly request help in this matter. If you could request a password change and tell me whether or not you receive an email with the password reset link, as well as what email type you are using (gmail, hotmail, yahoo, edu, etc.), it will help me immensely with identifying the root of this problem. I am not asking for you to change your password; I only need to know if the email arrives.
Thank you in advance for your assistance in this matter.

-Eric Mendelsohn
6) Message boards : News : New runs of MilkyWay Nbody out (Message 68739)
Posted 17 May 2019 by Eric Mendelsohn
Post:
after few days, let say a week, i earn approx 1.800 credits, i dont even know what are for those credits,, and if they are a lot or not... i dont think so.


Do you mean 1.8 or 1,800? Because 1.8 is FAR too small for computations over the course of the week.

Credits signify how much computing power you have donated to help further our research into tidal streams around the Milky Way Galaxy. The more intensive the computation, the longer it takes to compute, and the more credits you should earn as a result. For Nbody simulations, the run-times can vary greatly between runs. Short simulations typically give between 50 - 100 credits whereas the longer simulations which take a good fraction of the day can give between 500 - 2,000 credits. I'm not sure how many credits the Separation workunits give for each one, but I'd imagine it would be within the 50-100 credit range.

On this site, you can view a Certificate if you check under the "Community" tab. This will show a certificate you can print out that shows you how many "Cobblestones of Computation" (credits) you've earn and how that relates to the number of floating-point operations your computer contributed. This won't give an exact conversion rate since the Nbody credits are determined dynamically by the server, but it will give a general idea of how big an impact your donation if making for our research.

Thank you for sharing your computing power and showing an interest in our work. It is very much appreciated.

-Eric
7) Message boards : News : New runs of MilkyWay Nbody out (Message 68726)
Posted 13 May 2019 by Eric Mendelsohn
Post:
Right after you posted that, I opted out of N-Body, updated Boinc/Milkyway but for some reason, I am still receiving N-Bodys ??


I believe that's because your queue still has nbody workunits. I think if you give it a few days to finish the nbodies in the queue, you will not receive anymore workunits of that type. I advise that you do not abort the nbody workunits currently in your queue, as that will deny credit to those who are working on tasks validating said workunit. If you are still receiving nbody workunits after a week, please let me know.

-Eric
8) Message boards : News : New runs of MilkyWay Nbody out (Message 68712)
Posted 9 May 2019 by Eric Mendelsohn
Post:
Great news, everyone! The app selection preferences are available again in the Project Preferences! You can now choose to opt out of Nbody or Separation. Thank you all for your help in getting this feature back!
-Eric
9) Message boards : News : New runs of MilkyWay Nbody out (Message 68703)
Posted 7 May 2019 by Eric Mendelsohn
Post:
Thanks for GPUGrid preferences, Mr. Myers. It really helped. I believe I've found the main problem with why the preferences were lost. In the project_specific_prefs.inc file used in BOINC, there is a line of code which is necessary to show the preferences:
define ('APP_SELECT_PREFS', true);

When we were copying over the files to the new server, this line and a few others like it were omitted. After pasting the missing "define" lines back in the inc file, I loaded up the project preferences site to see if it was fixed, however, the preferences were still not visible to anyone. I feel like there's a step I'm missing when updating the website code. Does anyone have any suggestions?

-Eric
10) Message boards : News : New runs of MilkyWay Nbody out (Message 68685)
Posted 4 May 2019 by Eric Mendelsohn
Post:
Since the times for an nbody simulation can vary drastically depending on the 5 input parameters for our dwarf galaxy, it's hard for me to pin a percentage for dwarf progenitor generation. However, for the two-component 40,000-body progenitors we are currently running in our simulations, I want to say it takes about 1-3 minutes to generate the progenitor. So, if you were to run eight 8-threaded processes one at a time versus eight single-threaded processes simultaneously, the latter process would on average finish those eight runs 14 minutes faster than the former. But considering that these runs take between 3 and 24 hours to time evolve the system, an argument could be made that this time percentage for dwarf generation is insignificant. But since it takes about a month for runs to converge, those additional minutes could give us results a few days earlier.

Thank you for taking interest. If you have any other questions, please feel free to ask.

-Eric
11) Message boards : News : New runs of MilkyWay Nbody out (Message 68671)
Posted 3 May 2019 by Eric Mendelsohn
Post:
The main reason we are not running MT applications for milkyway_nbody anymore is because the progenitor dwarf galaxy generation is still a single-threaded process. Let's say you you wanted to run 8 cores on the multi-threaded version of milkyway_nbody. While the progenitor is being generated by a single core, the other seven sit idly by until the progenitor is created and placed in the simulation, which takes a considerable amount of time when using a two-component Plummer sphere. In that time creating the dwarf galaxy, the other seven cores could be creating progenitors for seven other single-threaded runs. Because of this, Jake and I agreed that only running single-threaded nbody applications would be a more efficient use of everyone's time and computing power.

On the topic re-adding the "opt out" preferences for Nbody and Separation, I came across this code among the old server's include files:

if ($app_types->cpu) {
    $project_pref_descs[] = new PREF_BOOL (
        tra("Use CPU")
            ."<br><span class=note>"
            .tra("Enforced by version 6.10+")
            ."</span>",
        "no_cpu",
        false,
        true
    );
}
if ($app_types->ati) {
    $project_pref_descs[] = new PREF_BOOL (
        tra("Use ATI GPU")
            ."<br><span class=note>"
            .tra("Enforced by version 6.10+")
            ."</span>",
        "no_ati",
        false,
        true
    );
}
if ($app_types->cuda) {
    $project_pref_descs[] = new PREF_BOOL (
        tra("Use NVIDIA GPU")
            ."<br><span class=note>"
            .tra("Enforced by version 6.10+")
            ."</span>",
        "no_cuda",
        false,
        true
    );
}
if ($app_types->intel_gpu) {
    $project_pref_descs[] = new PREF_BOOL (
        tra("Use Intel GPU")
            ."<br><span class=note>"
            .tra("Enforced by version 7.2+")
            ."</span>",
        "no_intel_gpu",
        false,
        true
    );
}


Does this look the like place where the Nbody opt-out preference should be located? I've searched this and many other files, but I still cannot find the original code that generated that preference in the old server. If I cannot find the old preferences, I will need to recreate them from scratch. This code will at least give me some place to start.

Again, thank you for all of your help.

-Eric
12) Message boards : News : New runs of MilkyWay Nbody out (Message 68647)
Posted 2 May 2019 by Eric Mendelsohn
Post:
I'm browsing through the old code used in the previous server, however, I cannot seem to find the old preference settings there either. Aside from updating the code to a new version of PHP, there aren't any visible differences that I can find between the project preferences between the old and new server code. How long ago were the preferences to opt out of Nbody or Separation last available? I apologize that this is taking much longer than I anticipated.
-Eric
13) Message boards : News : New runs of MilkyWay Nbody out (Message 68632)
Posted 30 Apr 2019 by Eric Mendelsohn
Post:
Do you remember what the option for opting out of N-body units was called? Was it "Run test applications?"? I'm still looking into the website code to resolve this.
-Eric
14) Message boards : News : New runs of MilkyWay Nbody out (Message 68620)
Posted 29 Apr 2019 by Eric Mendelsohn
Post:
We recently moved MilkyWay@home onto a new server, so it might just be that the preferences were not transferred over correctly. I'll try to figure out how to get that fixed.
-Eric
15) Message boards : News : New runs of MilkyWay Nbody out (Message 68578)
Posted 23 Apr 2019 by Eric Mendelsohn
Post:
Hello all,
I just wanted to let you know that new runs for the newest version of the MilkyWay@home Nbody program have just been released. The names of these new runs are:
-de_nbody_04_23_2019_v176_40k__data__1
-de_nbody_04_23_2019_v176_40k__data__2
-de_nbody_04_23_2019_v176_40k__data__3
I apologize for any inconveniences over the last few days. If you have any issues with these runs, please let me know on this thread and I will try to sort them out as quickly as I can.
Just so you know, some of the changes we made for this nbody version take runs that would've taken extremely long times to compute and return success immediately. As such, credit for nbody may be a little strange until the server recognizes the new average runtime. Also note that there is no longer support for multi-threaded.
Again, thank you all for your continued support.
-Eric Mendelsohn
16) Message boards : News : New version of MilkyWay Nbody (Message 68569)
Posted 23 Apr 2019 by Eric Mendelsohn
Post:
Hello all,
We have just released a new version of the MilkyWay@home Nbody application. We have not put up new runs for this yet. We will be putting up new runs next week or the following week. Thank you for your support!
-Eric Mendelsohn
17) Message boards : News : New MilkyWay@Home Developer (Message 67718)
Posted 21 Aug 2018 by Eric Mendelsohn
Post:
Hello all,

My name is Eric Mendelsohn, and I am a new developer working on the code for MilkyWay@Home. I am currently working on testing the impact of several parameters implicit within the N-body integrator used in MilkyWay@Home. I am also working on adding new gravitational potential models for the simulated bulge, disk, and halo of the Milky Way Galaxy. If you have any questions involving N-body, I will do my best to answer them as accurately as possible.

Thank you for your support!




©2019 Astroinformatics Group