By default, processes are bound to individual CPUs (either COREs or HWTHREADs, as defined by default or by user specification for the job). On nodes that are OVERSUBSCRIBEd (i.e., where the number of procs exceeds the number of assigned slots), the default is to not bind the processes.
Note
Processes from prior jobs that are already executing on a node are not “unbound” when a new job mapping results in the node becoming oversubscribed.
Binding is performed to the first available specified object type within the object where the process was mapped. In other words, binding can only be done to the mapped object or to a resource located beneath that object.
An object is considered completely consumed when the number of
processes bound to it equals the number of CPUs within it. Unbound
processes are not considered in this computation. Additional
processes cannot be mapped to consumed objects unless the
OVERLOAD
qualifier is provided via the --bind-to
command
line option.
Note that directives and qualifiers are case-insensitive
and can be shortened to the minimum number of characters
to uniquely identify them. Thus, L1CACHE
can be given
as l1cache
or simply as L1
.
Supported binding directives include:
NONE
does not bind the processesHWTHREAD
binds each process to a single hardware thread/ This requires that hwthreads be treated as independent CPUs (i.e., that either theHWTCPUS
qualifier be provided to themap-by
option or thathwthreads
be designated as CPUs by default).CORE
binds each process to a single core. This can be done whetherhwthreads
orcores
are being treated as independent CPUs provided that mapping is performed at the core or higher level.L1CACHE
binds each process to all the CPUs in anL1
cache.L2CACHE
binds each process to all the CPUs in anL2
cacheL3CACHE
binds each process to all the CPUs in anL3
cacheNUMA
binds each process to all the CPUs in aNUMA
regionPACKAGE
binds each process to all the CPUs in aPACKAGE
Any directive can include qualifiers by adding a colon (:) and any
combination of one or more of the following to the --bind-to
option:
OVERLOAD
indicates that objects can have more processes bound to them than CPUs within themIF-SUPPORTED
indicates that the job should continue to be launched and executed even if binding cannot be performed as requested.
Note
Directives and qualifiers are case-insensitive.
OVERLOAD
is the same as overload
.