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Special Forums UNIX and Linux Applications High Performance Computing Memory Barriers for (Ubuntu) Linux (i686) Post 302430998 by fpmurphy on Sunday 20th of June 2010 11:01:55 AM
Old 06-20-2010
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In my system, if I had a massive 100-core machine, I would only create 100 threads, if I had a 8 cores- 8 threads, 16 cores -16 threads etc. There is a 1:1 mapping of cores to threads where each thread runs on a designated core.

Just out of curiosity how are you going to ensure that each thread runs on a designated core? And have you thought through the overhead of attempting to ensure that each thread runs on a designated core?
 

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pset_ctl(2)							System Calls Manual						       pset_ctl(2)

NAME
pset_ctl() - processor set control SYNOPSIS
DESCRIPTION
The function provides a means to query the system processor set configuration and assignment information. The request argument specifies what information is needed for the pset processor set. The following request values are supported: Return the ID of the processor set binding for the calling thread. The pset and id arguments are ignored. Return the ID of the first locality domain contributing to the processor set pset. The id argument is ignored. Return the ID of the first processor in the processor set pset that is in the proximity of the processor specified by id. Even when the processor given by id is enabled, the return value will be -1 if none of the proximate processors contribute to the processor set pset. If the processor given by id is not enabled, -1 is returned. See mpctl(2) for details on proximate processors. Return the ID of the first processor set in the system. The pset and id arguments are ignored. Return the ID of the first processor in the processor set pset. It will return -1 if the processor set is empty. Any processors in the processor set that is in transition are ignored. The id argument is ignored. Return the ID of the next locality domain after the locality domain specified in id that contributes to the processor set pset. Typically, is called to determine the first locality domain in a processor set. is then called in a loop (until the call returns -1) to determine the IDs of the remaining locality domain in the processor set. Return the ID of the next processor in the processor set pset that is in the proximity of the processor specified by id. Typically, is called to determine the first proximate processor. is then called in a loop (until the call returns -1) to deter- mine the IDs of the remaining proximate processors. Return the ID of the next processor set in the system after pset. The id argument is ignored. Typically, is called to determine the first processor set. is then called in a loop (until the call returns -1) to determine the IDs of the remaining processor sets in the system. Return the ID of next processor in the processor set pset after the processor specified in id. Typically, is called to determine the first processor in a processor set. is then called in a loop (until the call returns -1) to determine the IDs of the remaining processors in the processor set. Return the number of locality domains that have at least one processor assigned to the processor set pset. The id argument is ignored. Return the number of processors assigned to the processor set pset that are in the proximity of the processor specified by id. Even when the processor given by id is enabled, the return value will be 0 if none of proximate processors contribute to the processor set pset. If the processor given by id is not enabled, -1 is returned. Return the current number of processor sets in the system. It will always be greater than or equal to one. The pset and id arguments are ignored. Return the number of processors assigned to the processor set pset. Any processors in the processor set that is in transition are not included. The id argument is ignored. Return number of processors contributed by the locality domain specified by id to the processor set pset. Return the ID of the processor set assigned for the processor specified in id. If the processor is not enabled or is in transition from one processor set to another, -1 is returned with an error. The pset argument is ignored. Logical Processor and Processor Core Information On systems with the Hyper-Threading (HT) feature enabled, each processor core may have more than one hyper-thread per physical processor core. When hyper-threading is enabled at the firmware level, each hyper-thread is represented to the operating system and applications as a logical processor (LCPU). Hence the basic unit of any topology information is a logical processor. However, some applications may want to get the system topology information at the physical processor core level. Returns the number of processor cores assigned to the processor set pset. Any processor cores in the processor set that are in transition are not included. The id argument is ignored. Returns the ID of the first processor core in the processor set pset. It will return -1 if the processor set is empty. Any processor cores in the processor set that is in transition are ignored. The id argument is ignored. Returns the ID of the next processor core in the processor set pset after the processor specified in id. Typically, is called to determine the first processor core in a processor set. is then called in a loop (until the call returns -1) to determine the IDs of remaining processor cores in the processor set. Returns the number of enabled processor cores assigned to the processor set pset. Any user may query the system processor set topology using the function. Use with name to see if the processor set functionality is supported by the underlying HP-UX operating system version. RETURN VALUE
returns a value based on on successful completion. Success. The value is based on the request. Failure. is set to indicate the error. ERRORS
sets to one of the following values if the corresponding condition is detected. The request is invalid. The specified processor set pset, or the processor or the locality domain specified by id is invalid. The request is and there is no other processor set after pset, or the request is and there is no other processor after id in pset, or the request is and there is no other locality domain after id in pset, or the request is and there is no other proxi- mate processor after id in pset. The request is or and the processor specified by id is not enabled. The processor set functionality is not supported by the underlying HP-UX version. EXAMPLES
Get total count and IDs of all processor sets in the system. AUTHOR
was developed by HP. SEE ALSO
psrset(1M), mpctl(2), pset_assign(2), pset_bind(2), pset_create(2), pset_destroy(2), pset_getattr(2), pset_setattr(2), sysconf(2), privi- leges(5). pset_ctl(2)
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