Administering Platform LSF - SAS

Span String
Span String
Syntax
A span string specifies the locality of a parallel job. If span is omitted, LSF
allocates the required processors for the job from the available set of
processors.
Two kinds of span string are supported:
◆ span[hosts=1]
Indicates that all the processors allocated to this job must be on the same
host.
◆ span[ptile=value]
Indicates the number of processors on each host that should be allocated
to the job.
where value is:
❖
❖
Default ptile value, specified by n processors. For example:
span[ptile=4]
The job requests 4 processors on each available host, regardless of how
many processors the host has.
Predefined ptile value, specified by ’!’. For example:
span[ptile='!']
uses the predefined maximum job slot limit lsb.hosts (MXJ per host
type/model) as its value.
If the host or host type/model does not define MXJ, the default predefined
ptile value is 1.
❖ Predefined ptile value with optional multiple ptile values, per host
type or host model:
✧ For host type, you must specify same[type] in the resource
requirement. For example:
span[ptile='!',HP:8,SGI:8,LINUX:2] same[type]
The job requests 8 processors on a host of type HP or SGI, and 2
processors on a host of type LINUX, and the predefined maximum
job slot limit in lsb.hosts (MXJ) for other host types.
✧ For host model, you must specify same[model] in the resource
requirement. For example:
span[ptile='!',PC1133:4,PC233:2] same[model]
The job requests 4 processors on hosts of model PC1133, and 2
processors on hosts of model PC233, and the predefined maximum
job slot limit in lsb.hosts (MXJ) for other host models.
See “Controlling Processor Allocation Across Hosts” on page 441 for more
information about specifying span strings.
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Administering Platform LSF