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World Community Grid Forums
Category: Support
Forum: Community-maintained FAQs [authorized posting allowed]
Thread: BOINC: "Elapsed" [Wallclock] Is Not Same as CPU Time as of version 6.6 |
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Thread Status: Active Total posts in this thread: 4
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Those who've moved on to use the 6.6 client [see release notes ] will have found out that the runtime column showing in the BOINC Manager > Advanced View > Tasks tab is now named Elapsed **. This is in fact representing Wall-clock i.e. the time the work unit is in memory and allowed to run, even when the operating system is not allocating all the idle amount of CPU time to the science application. Consequently, if doing intense user activity such as gaming, photo editing et cetera, the difference between the Elapsed time and CPU time will get quite far apart.
----------------------------------------When you want to know the real computing time on a running task, select the one of interest and hit the Properties button in left margin. A pop-up will appear displaying the old CPU times and the Elapsed aka Wall-Clock time, the ratio representing the efficiency at which the CPU is used. The sample below showing that 14 minutes of computer time went to other activities on the system. Caveat: Some have experienced the Elapsed column between the [Task] Name and Progress columns to not show. Position the mouse over the column header separation indicator and expand to desired size. It will be remembered next time the GUI is started. NB: As in the past, the same CPU time is measured, recorded, reported and shown in the Result Status page, as is counted against Badge accumulated time. ** The BOINC Manager Simple View GUI names it Elapsed Time which is actually the CPU time!
WCG
----------------------------------------Please help to make the Forums an enjoyable experience for All! [Edit 5 times, last edit by Sekerob at Sep 10, 2009 6:11:29 AM] |
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
For users on client 6.6 and up, occasionally fear strikes after the computer hung up or had an acute power out. After restarting and looking into BOINC Manager one discovers that the "Elapsed" aka "Wallclock" time has suddenly dropped back to zero or a large chunk of time has disappeared. Before hitting the panic button, first select the task in question, hit the properties button and compare the Elapsed time with the CPU time. You will discover nothing much was lost as the science correctly remembered the progress from last saved checkpoint in percent and CPU time. Until the task is finished that wallclock time will not correct and does lead to temporary understated projection of Time To Complete (TTC). This is because the client uses the wallclock time and not the CPU time to calculate this value.
----------------------------------------To illustrate here a screenshot of a 6.10.17 BOINC manager task view on Linux after a system hang. NB: This issue has been fixed in release 6.10.57 and up. 
WCG
----------------------------------------Please help to make the Forums an enjoyable experience for All! [Edit 3 times, last edit by Sekerob at Sep 15, 2010 7:24:32 PM] |
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Some research applications have a limitation aka "cap" on how long they are allowed to run before the calculations are ended, not to let it go too long. Presently, as of September 15, 2010 these applications are:
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With clients 6.4 and later, the task progress view is showing the wallclock time also known as "Elapsed". Since the effective time a task can or is allowed to use the CPU, the principle being to only use spare cycles, it will happen that the "elapsed" time will exceed that restriction. When this is observed and you are not comfortable, go to the Tasks tab in BOINC Manager's "Advanced" view, select the overlong running task and select the "Properties" button in the left margin. Here you will see the true CPU time. Tasks are not always precisely capped at that CPU hour limit, rather some are allowed to finish the last step, so they will be computing a bit longer. Let them run to completion. Related Topics: "Maximum run time exceeded" / "Maximum elapsed time exceeded.". (usually 10 times the preset number of FPOPS calculations defined for a task) Return to the Start Here FAQ index
WCG
----------------------------------------Please help to make the Forums an enjoyable experience for All! [Edit 2 times, last edit by Sekerob at May 28, 2011 8:13:35 AM] |
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Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
The BOINC manager gives only sparse information on a progressing task. As noted though in several posts in this thread, allot of detail can be seen by selecting a running task, then hitting the Properties button in the left margin. The below is an example of what's included in the upcoming 6.12 client. Some features added since 6.6:
----------------------------------------- The maximum RAM use and Virtual Memory (swap file use on disk). - Original estimated GLOPS in a task and the present speed of processing. - When the task was assigned to the client, in local time.  NB: This client release is likely not going to adopted by WCG for lack of significant feature additions. Related topics: Return to the Start Here FAQ index
WCG
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