[Adywebb]

WCG used to send out the same work unit (WU) to 4 different Boinc machines for processing - and needed 3 correctly returned for validation to be successful and points issued.

This means in effect that 1 WU's crunching is 'wasted' as it is not required for the validation - it is used as a back-up in case one of the others fails.

To reduce this wastage - as from 20.05.06 WCG will only be sending out 3 of the same WU for crunching, and will only send out a fourth if one is returned with an error or is timed out etc.

What this means for us is that it may take longer for your completed WU's to be validated - if theres an error you will have to wait for another one to be sent out and crunched.

But dont worry - you will get the points in the end

[feckit]

Cheers for that Ady

[TriplexDread]

I dont care as long as it works

Cheers for the info dude

[cirianz]

second that, Thanks Ady

[V_R]

An update from WCG


Changes to BOINC Workunit Distribution Policy

We made a change to the way that BOINC workunits are distributed on Friday, May 19th starting at 12:00 UTC. This change will increase the efficiency of the BOINC portion of the grid by over 25%. This will allow us as a community to complete more research for projects run on World Community Grid.

World Community Grid is a public distributed computing grid. All public distributed computing grids have to assume that there are a few computers which will compute results incorrectly for various reasons such as overclocking, viruses or deliberate tampering. In order to insure that the data is accurate, each workunit must be sent to multiple computers and the results from those computers compared in order to validate that they calculated the same result. If they do not agree, then the workunit is sent out to additional computers to obtain more results to compare.

The BOINC grid at World Community Grid has been sending each workunit to four different computers and running validation on the workunit when three of those computers have returned a result. If all three computers have computed the same result then the result is accepted as correct. If the results are not the same, then the workunit is sent to additional computers. Each time a result is received it is compared to the other results returned until at least three or a majority (whichever is greater) agree.

In a majority of cases, the first three results returned for a workunit agree. This means that the fourth result was not needed for validation and was therefore not necessary to verify the result.

We have changed the way this works so that initially the workunit is only sent to three computers instead of four. This will increase efficiency because those computers that would have previously returned the fourth result are instead doing work on a new workunit. As a result, we will be able to compute more work.

However, this will impact some users because the fourth result did play a role in the grid. About 15% of the results that we send out are not returned with a successful result. Most of these are due to the result never being returned. BOINC will automatically handle this condition by detecting that a result has not been returned and it will send the workunit out to an additional computer. However, this will impact users because in the event that one of the results is not returned they will have to wait until the workunit is sent out again and the result is returned before their results can be validated. This means that in some cases members will experience an additional delay in being awarded credit for the work they have returned. Members will always receive credit for workunits completed. However, there may be a delay before they receive credit for that specific workunit if it is necessary to send the work to a fourth user. Members can check the status of results they have returned on the BOINC results page at: https://secure.worldcommunitygrid.or...oincResults.do

In order to reduce the delay associated with this change, we have made some additional changes so that any results sent out after the initial three results will be sent to a host that is reliable and processes results quickly.

Source

[Adywebb]

Originally Posted by V_R

In order to reduce the delay associated with this change, we have made some additional changes so that any results sent out after the initial three results will be sent to a host that is reliable and processes results quickly.

I must be fast an reliable then, cos I have had a few of them 4th results sent to me

[feckit]

Cheers for that V_R I will digest this news over a pint or 3

[Adywebb]

Don't let it interfere with your drinking feckit - just read the precis version in my first post

[V_R]

Lol, Well thats just Knreed's offical response to all the 'chatter' going on in the forums about the validation issues.

[Adywebb]

Sorry V_R - I wasn't knocking it - just didn't want feckit to miss out on his drinking