It is not really what is going on at the server end from the client end. We know how it works overall, so we can see how the details mesh. This would not really be obvious just by watching the client.
-----Original Message----- From: Charles Elliott [mailto:[email protected]] Sent: Friday, June 21, 2013 7:51 AM To: McLeod, John; 'Chanda Sarkar'; 'Christian Beer' Cc: [email protected] Subject: RE: [boinc_dev] Questions around BOINC Instead of all these questions, why don't you just attach a computer to Boinc's SETI@Home project, or another -- there are tens of them -- and watch how it works. Your questions seem to fundamental and trivial to those who have been using Boinc for years. Charles Elliott > -----Original Message----- > From: boinc_dev [mailto:[email protected]] On Behalf > Of McLeod, John > Sent: Thursday, June 20, 2013 11:53 AM > To: Chanda Sarkar; Christian Beer > Cc: [email protected] > Subject: Re: [boinc_dev] Questions around BOINC > > Each work unit will be made into one or more identical tasks depending > on the initial replication setting. Each of these tasks will be sent > to a different computer. When the task on an individual computer is > completed, the result of the computation will be uploaded. If more > than one task was sent, the results will be compared in the validator. > > Some applications can do a quick reverse computation to see if a result > is valid or not, others require two results of the same computation to > compare to each other. Unfortunately, individual computers cannot be > trusted as they may overheat, be overclocked, have a random computation > error, or (grumble) be maliciously modified so that credit accumulates > faster. Hence the need for validation of computational results. > > SETI Classic had a handful of clients that were modified such that they > would return pre-calculated results as quickly as the system would > allow so that they would gain credits faster - thus potentially harming > the science being done. This handful of clients returned a large > number of invalid results. The same thing could happen in BOINC if > there is no validation. > > -----Original Message----- > From: boinc_dev [mailto:[email protected]] On Behalf > Of Chanda Sarkar > Sent: Thursday, June 20, 2013 7:42 AM > To: Christian Beer > Cc: [email protected] > Subject: Re: [boinc_dev] Questions around BOINC > > Hi, > > Thanks for the information! But the URL that I read - > http://boinc.berkeley.edu/trac/wiki/JobIn , says, in *JOB *section* - > '*One > or more *results*, each of which describes an instance of a > computation, > either unstarted, in progress, or completed. *The BOINC client software > refers to results as "tasks"**'. *So, one work unit(job) may be > associated > with one or more results? More over what is the exact meaning of result > file is it a single output file or a collection of output files that > refers > to single work unit. > > One more question that comes into my mind comes after reading - > http://www.irelandboinc.com/how-boinc-works. > Under Credit section - 'Each work unit may be sent to several > computers' > and 'When at least two results have been returned, the server compares > them. If the results agree, then users are granted credits.'. > According to this statement, same work unit(job) are > sent to > different machines for computation. So, does that mean same work > unit(or > job) may span multiple machines?.. which would contradict to the > earlier > mail. > > Do correct me if I am wrong > > Thanks, > Chanda > > > > On Thu, Jun 20, 2013 at 2:36 PM, Christian Beer <[email protected]> > wrote: > > > Hi, > > > > I'm not Rom but I hope I can help you too. > > > > 1. That scenario is already the principal design behind BOINC. Once a > > task is associated with a host (gets send) this will not change. So > in > > your example: 't1' will only be processed on 'M1', if for some reason > > this is not succesfull the server will create 't3' and send this to > 'M3'. > > > > 2. What you see in your Screenshot is exact the behaviour I described > > above. 't1' was created when the workunit (job) was created (because > of > > initial_replication=1) it got send to Computer 1619876 ('M1') on June > 13 > > later (on June 17) this computer reported that it has detached from > the > > project and discarded all remaining tasks. So the server created > another > > task ('t2') and it got send to 'M2' (1518828). This is also a normal > > BOINC behaviour. If the first task is successfull there will be no > > second task because the workunit is considered complete if one task > is > > succesfull (minimum_quorum=1). > > > > Regards > > Christian > > > > Am 20.06.2013 10:53, schrieb Chanda Sarkar: > > > Hi Rom, > > > > > > I have two questions around BOINC - > > > > > > 1. Is there any chance that single task within a work unit is > > > processed only once on a single machine and no other machine. > > > For example : > > > Assume there is a work unit 'A' that has two tasks 't1' and 't2'. > 't1' is > > > send to machine 'M1' for processing and 't2' is send to machine > 'M2' for > > > processing. Is it a possibility that 't1' which is processed on > machine > > > 'M1' will never be processed for any other machine ? > > > > > > > > > 2. Is there any possibility that task within a work unit may > be > > > generated with unpredictable time span which could be a day or > more? I am > > > attaching a snap shot for the same > > > URL : http://screencast.com/t/HOvebaVpP0N > > > In the above image it is seen for a work unit > > > > 'cryo_bk__chain_I_subrun_000_SAVE_ALL_OUT_IGNORE_THE_REST_86456_479' > that > > > has two tasks. One is created on 13th June 2013 and other on 17th > June > > > 2013. Is there a possibility that tasks within work units can be > created > > > with unpredictable time span? Please correct me if I am wrong. > > > > > > > > > Thanks, > > > Chanda > > > _______________________________________________ > > > boinc_dev mailing list > > > [email protected] > > > http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev > > > To unsubscribe, visit the above URL and > > > (near bottom of page) enter your email address. > > > > > _______________________________________________ > boinc_dev mailing list > [email protected] > http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev > To unsubscribe, visit the above URL and > (near bottom of page) enter your email address. > _______________________________________________ > boinc_dev mailing list > [email protected] > http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev > To unsubscribe, visit the above URL and > (near bottom of page) enter your email address. _______________________________________________ boinc_dev mailing list [email protected] http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev To unsubscribe, visit the above URL and (near bottom of page) enter your email address.
