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Administering Platform LSF - SAS

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Chapter 11<br />

Deadline Constraint and Exclusive Scheduling<br />

Exclusive Scheduling<br />

About exclusive scheduling<br />

Exclusive scheduling gives a job exclusive use of the host that it runs on. <strong>LSF</strong><br />

dispatches the job to a host that has no other jobs running, and does not place<br />

any more jobs on the host until the exclusive job is finished.<br />

How exclusive scheduling works<br />

When an exclusive job (bsub -x) is submitted to an exclusive queue<br />

(EXCLUSIVE = Y in lsb.queues) and dispatched to a host, <strong>LSF</strong> locks the host<br />

(lockU status) until the job finishes.<br />

<strong>LSF</strong> cannot place an exclusive job unless there is a host that has no jobs<br />

running on it.<br />

To make sure exclusive jobs can be placed promptly, configure some hosts to<br />

run one job at a time. Otherwise, a job could wait indefinitely for a host in a<br />

busy cluster to become completely idle.<br />

An exclusive job cannot preempt another job, and cannot be preempted by<br />

another job.<br />

Configuring an exclusive queue<br />

To configure an exclusive queue, set EXCLUSIVE in the queue definition<br />

(lsb.queues) to Y.<br />

Configuring a host to run one job at a time<br />

Submitting an exclusive job<br />

To make sure exclusive jobs can be placed promptly, configure some singleprocessor<br />

hosts to run one job at a time. To do so, set SLOTS=1 and HOSTS=all<br />

in lsb.resources.<br />

To submit an exclusive job, use the -x option of bsub and submit the job to<br />

an exclusive queue.<br />

<strong>Administering</strong> <strong>Platform</strong> <strong>LSF</strong> 175

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