mpctl.2 (2010 09)

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mpctl(2) mpctl(2)

If the process speciﬁed by pid is a multithreaded process, all LWPs (lightweight

processes) in the target process will have their locality domain assignment

changed to what is speciﬁed. However, if any LWP belongs to a processor set

different from the target process, and if the speciﬁed locality domain does not

contribute any processor to that locality domain, the binding assignment of such

an LWP is not changed.

MPC_SETLWPLDOM

This request synchronously assigns LWP (lightweight process) lwpid to locality

domain ldom. The LWP may now run on any processor within the locality

domain. The new locality domain assignment is returned. This option can be

used to change the locality domain assignment of LWPs in any process.

The lwpid

MPC_SELFLWPID

may be used to refer to the calling LWP.

The ldom

MPC_LDOMNOCHANGE

may be passed to read the current assignment.

The ldom

MPC_LDOMFLOAT

may be used to break any speciﬁc-locality domain

assignment. This allows the LWP to ﬂoat to any locality domain.

When a processor is ready to choose another LWP to execute, and the highest

priority

SCHED_FIFO LWP is bound to a processor in a different locality

domain, then that LWP will not be selected to execute on the selecting processor,

but instead will wait for a processor on the locality domain to which it was

bound. The selecting processor will then choose a lower priority LWP to execute

on the processor.

NOTE: This option will not guarantee compliance with POSIX real-time

scheduling algorithms.

Obtaining Processor and Locality Domain Binding Type

These options return the current binding type for the speciﬁed process or LWP.

int mpctl(mpc_request_t request, spu_t spu, pid_t pid);

int mpctl(mpc_request_t request, spu_t spu, lwpid_t lwpid);

The request argument determines the precise action to be taken by mpctl() and is one of the following:

MPC_GETPROCESS_BINDINGTYPE

Warning: This call is OBSOLETE and is only provided for backwards compatibil-

ity.

This request returns

MPC_ADVISORY or MPC_MANDATORY

to indicate the

current binding type of the process speciﬁed by pid . The spu argument is

ignored. If the target process has a binding type of something other than

MPC_MANDATORY the value MPC_ADVISORY will be returned.

MPC_GETPROCESS_BINDVALUE

This request returns the current binding type of the process speciﬁed by pid.

The spu argument is ignored.

Current valid return values are

MPC_NO_BINDING (no binding),

MPC_SPU_BINDING (advisory processor binding),

MPC_SPU_FORCED_BINDING (processor binding), and MPC_LDOM_BINDING

(locality domain binding). Other binding types may be added in future releases

and returned via this option. Applications using this option should be written to

handle other return values in order to continue working on future releases.

MPC_GETLWP_BINDINGTYPE

Warning: This call is OBSOLETE and is only provided for backwards compatibil-

ity.

This request returns

MPC_ADVISORY or MPC_MANDATORY to indicate the

current binding type of the LWP speciﬁed by lwpid . The spu argument is

ignored. If the target LWP has a binding type of something other than

MPC_MANDATORY the value MPC_ADVISORY will be returned.

MPC_GETLWP_BINDVALUE

This request returns the current binding type of the LWP speciﬁed by lwpid.

The spu argument is ignored.

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