3.6 Scheduling Cores
In TORQUE 2.4 and later, users can request specific cores on a node at job submission by using geometry requests. To use this feature, users specify the procs_bitmap resource request of qsub -l at job submission.
3.6.1 Geometry Request Configuration
A Linux kernel of 2.6, or later, is required to use geometry requests. If the operating evnironment is suitable for geometry requests, configure TORQUE with the --enable-geometry-requests option.
> ./configure --prefix=/home/john/torque --enable-geometry-requests
3.6.2 Geometry Request Usage
Once enabled, users can submit jobs with a geometry request by using the procs_bitmap=<string> resource request. procs_bitmap requires a numerical string made up of 1's and 0's. A 0 in the bitmap means the job can not run on the core that matches the 0's index in the bitmap. The index is in reverse order of the number of cores available. If a job is submitted with procs_bitmap=1011, then the job requests a node with four free cores, and uses only cores one, two, and four.
qsub -l procs_bitmap=0011 ossl.sh
In the above example, the submitted job can run only on a node that has four cores. When a suitable node is found, the job runs exclusively on cores one and two.
3.6.3 Geometry Request Considerations
As stated above, jobs with geometry requests require a node with all of its cores available. After the job starts running on the requested cores, the node cannot run other jobs, even if the node has enough free cores to meet the requirements of the other jobs. Once the geometry requesting job is done, the node is available to other jobs again.
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