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View Full Version : CPDN on Boinc- how it works



LP_
06-27-2006, 03:55 AM
This is an attempt to explain how credits work on CPDN and Boinc.
From the CPDN forum- Link (http://www.climateprediction.net/board/viewtopic.php?p=27864#27864)



This post is an attempt to explain the trickle and result reporting sequence and how they relate to credits and the result's server state, outcome and client state.

To avoid any possible confusion I'll refer to a result running on a client as a model.

Trickles

A model generates a trickle to upload to the CPDN scheduler every 10802 timestep. These tell the server that the model is still running and generate the credits for the result (94.5175 cobblestones per trickle and 6805.26 for a completed run).

At the end of each phase the model generates a 'mega-trickle' containing the list of global mean annual averages for temperature and precipitation. These are used to generate the graphs that can be viewed on the result's page on the CPDN website.

It is not essential that trickles are uploaded immediately. Many users on dial-up systems who are only running CPDN choose to delay uploading their trickles until they have completed the model, but they should bear in mind that the scheduler may not accept all of the trickles in one batch. See here, for further details (it is possible that ths problem was fixed in the recent server upgrade, but that has yet to be confirmed).

Results

When a client finishes processing a model it generates 5 result files and the local status on the client is set to 'Uploading'. Once the result files have been sent to the required upload server they are deleted and the local status on the client is changed to 'Ready to report'.

The next scheduler request will cause the server to update the status information on the result's page on the website. The sheduler's acknowledgement of the result completion causes the client to clear the model to from its work list.

The status information for a result doesn't rely on the scheduler having received all 72 trickles.

Result status information

Server state

The server state of a result can have any of the following values:

* Inactive The result is not ready to send (e.g. its input files are not yet available).

* Unsent - The result is waiting to be sent to a client for calculation.

* In Progress - The result has been sent to a client and the server is waiting to be notified of its completion.

* Over - The result has been sent to a client and has either been completed or passed its reporting deadline.

Outcome

The outcome of a result is only defined if its server state is Over. It can take the following values:

* Success - The result was completed successfully by a client.

* Couldn't send - The server wasn't able to send the result to a client (perhaps because the resource requirements were too large for the client).

* Client error - The result was sent to a client and an error occurred.

* No reply - The result was sent to a client but was not returned within the reporting deadline.

* Didn't need - The result wasn't sent to a client because enough other results were returned for this work unit.

Client state

The client state of a result indicates the has the following values:

* New - The result has yet to be sent out or is being processed by a client.

* Done - The client has successfully completed the result.

* Downloading - The client couldn't download the application or input files.

* Computing - An error occurred during computation on the client.

* Uploading - The client couldn't upload the output files.

LP_
06-27-2006, 03:57 AM
It would be nice if someone can sticky this one.:)

Rinsewand
06-27-2006, 04:33 AM
cheers for that LP! however, i still get get its straight in my head whether the speed of the pc makes a difference... Im guessing a timestep is a fixed period of time and not down to the pc running it?

RwD

Rinsewand
06-27-2006, 04:37 AM
ahh righty - just been reading the forums and found this http://www.climateprediction.net/board/viewtopic.php?t=2298

a timestep is in the model, so changes in length depending on the pc used. So it is processor based, but not BOINC benchmark based... w00t

RwD

LP_
06-27-2006, 04:41 AM
cheers for that LP! however, i still get get its straight in my head whether the speed of the pc makes a difference... Im guessing a timestep is a fixed period of time and not down to the pc running it?

RwD

I'm guessing that a timestep is like a big "frame" in F@H, and the speed of the cpu does matter, but since these are huge work units, maybe the speed difference is not so great?

I'm thinking that the faster rigs would make more of an impact in projects with fast work units, and CPDN can be put on "set it and forget it" rigs?

Rinsewand
06-27-2006, 04:47 AM
Possibly, though i have a feeling the fast rigs may be able to get through WUs quickly. But yes, it'll be easier on set and forget rigs.

RwD

LP_
06-27-2006, 05:09 AM
I like your find in forum. It explains things much clearer. :D
I need to copy that and save it for future reference.
You should make a separate post with that info, that can be locked and stickied for the new comers. :D

[XC]thewildblue
06-27-2006, 05:30 AM
So we dont want this one stickied then ? Or do we ?

Rinsewand
06-27-2006, 05:32 AM
this one if you can edit that forum link into the first post, if not ill write another thread tomorow (bit busy today)

cheers

RwD