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The 3G Bridge accounting interface provides information that is required by the EGI Grid Federation to accept Desktop Grids as federation components.
The interface provides accounting information on a job-by-job basis. The information available through this interface is described in the following table.
| Name | Unit | Description |
|---|---|---|
| start_time | UNIX timestamp | Start time of the job as reported by the DG |
| end_time | UNIX timestamp | End time of the job as reported by the DG |
| wallclock_time | s | Start time - End time |
| cpu_time | s | Net CPU time consumed by the job |
| memory | byte | Approx. memory consumed by the job (see remarks below) |
| host_flops | 1/s | Floating point performance of the executing host |
| host_intops | 1/s | Integer performance of the executing host |
| host_ncpus | 1 | Number of processors in the executing host |
The following are implementational details included for the sake of completeness; the client using this interface need not be concerned about it.
Meta-jobs present two issues.
First, the accounting information of a meta-job must be an aggregation of information on its sub-jobs. The host_flops and host_intops values are particularly problematic. For example, the host_flops of the participating hosts cannot simply be summed: each term must be weighted with the actual participation of the given host. The solution is the following. The number of floating point operations performed on each host is computed. The total number of operations divided by the total CPU time will give the actual performance of the infrastructure executing the meta-job:
aggregate_host_flops = sum(cpu_time*host_flop)/sum(cpu_time)
The aggregation function used for meta-jobs are summarized in the following table:
| Name | Aggregator in case of meta-jobs |
|---|---|
| start_time | Min |
| end_time | Max |
| wallclock_time | Max - Min |
| cpu_time | Sum |
| memory | Sum |
| host_flops | Sum(cpu_time*host_flops)/Sum(cpu_time) |
| host_intops | Sum(cpu_time*host_intops)/Sum(cpu_time) |
| host_ncpus | Sum |
Second, as a meta-job progresses, when a sub-job has finished, its output is processed and the sub-job is deleted immediately. Therefore, the sub-job information must be saved before it is lost. This is done in database internally, with a trigger. The saved information is aggregated to produce the accounting information of the meta-job.
The interface is provided only by the REST interface. The interface is enabled by default. To disable it, remove the corresponding line from 3gb.php:
RESTHandler::addHandler('AccinfoHandler'); ... RESTHandler::addHandler('JobsHandler');
Make sure that the registration of AccinfoHandler precedes the registration of JobsHandler, as the URL patterns of these handlers overlap.
The database has to provide the necessary functionality to enable the interface. The schema is defined in db/egi-accounting.sql.
mysql << db/egi-accounting.sql
The accounting information can be accessed through <job's URL>/accinfo
For example:
JOBID=e8d8e4f4-27f0-409f-ba80-f9f9e33d3242 wget "http://home.edges-grid.eu/home/download/wss/jobs/$JOBID/accinfo"
e8d8e4f4-27f0-409f-ba80-f9f9e33d3242 1361961911 1362010369 48458 1259713.9488 1339227204000 27077851019757.2 82720014025364.8 47083
The result is the record containing the job identifier followed by the fields described in the table above in order. The syntax is as described in the REST interface manual (space delimited lines by default).
