NAME    [Toc]    [Back]

       numa_scheduling_groups  -  HP  Tru64  UNIX NUMA Scheduling
       Groups description (libnuma library)

DESCRIPTION    [Toc]    [Back]

       Normally, the kernel scheduler attempts to distribute  the
       workload  evenly  over the entire machine. When the system
       resources are evenly utilized, the machine  is  considered
       to be balanced. When balancing the workload, the scheduler
       operates in a context-free manner; that is, processes  may
       be  distributed to various CPUs, or other resources, without
 regard  to  their  function  or  relationship  to  one
       another.  In  certain  cases,  a user may wish to bundle a
       group of processes together so that they have equal access
       to  the  same  system resources. For instance, cooperating
       processes that share the same physical memory may  perform
       better  if all of these processes execute on CPUs that are
       local to that memory.

       NUMA Scheduling Groups (NSG) cause the scheduler load-balancing
 system to treat all members of an NSG as a unit. If
       one process belonging to an NSG moves  from  one  Resource
       Affinity Domain (RAD) to another, all other members of the
       NSG have to move with it.

       NSGs and their members have the following characteristics:
       The  resource  domain  of the first process joining an NSG
       provides the initial resource  domain  location  for  that
       NSG, called the NSG home RAD.  All other processes joining
       the NSG (through the nsg_attach_pid()  function)  will  be
       migrated  to  the NSG home RAD.  If the joining process is
       not allowed to migrate, the nsg_attach_pid() function will
       fail.   To  support  load  balancing, an NSG is allowed to
       migrate to any RAD on the system if none of its members is
       bound  to  a  specific resource (such as another RAD, CPU,
       and so on).  An NSG member is allowed to attach to or bind
       to  a  resource only if no other members are bound to different
 resources. The entire NSG will migrate to  the  RAD
       containing  the  resource  at the time it was successfully
       bound.  If one NSG member is  bound  to  a  resource,  all
       other  members  of that NSG are also bound to the RAD containing
 that resource, because the NSG and, therefore  its
       members, is no longer allowed to migrate.

SEE ALSO    [Toc]    [Back]

       Commands: runon(1)

       Functions:          numa_intro(3),         bind_to_cpu(3),
       nsg_attach_pid(3),   nsg_detach_pid(3),    nsg_destroy(3),
       nsg_get(3), nsg_get_nsgs(3), nsg_get_pids(3), nsg_init(3),
       nsg_set(3),      rad_attach_pid(3),       rad_bind_pid(3),
       rad_detach_pid(3)



                                        numa_scheduling_groups(4)