CHECK_ASYM_PACKING(9)                     Driver Basics                     CHECK_ASYM_PACKING(9)



NAME
       check_asym_packing - Check to see if the group is packed into the sched doman.

SYNOPSIS
       int check_asym_packing(struct lb_env * env, struct sd_lb_stats * sds);

ARGUMENTS
       env
           The load balancing environment.

       sds
           Statistics of the sched_domain which is to be packed

DESCRIPTION
       This is primarily intended to used at the sibling level. Some cores like POWER7 prefer to
       use lower numbered SMT threads. In the case of POWER7, it can move to lower SMT modes only
       when higher threads are idle. When in lower SMT modes, the threads will perform better
       since they share less core resources. Hence when we have idle threads, we want them to be
       the higher ones.

       This packing function is run on idle threads. It checks to see if the busiest CPU in this
       domain (core in the P7 case) has a higher CPU number than the packing function is being
       run on. Here we are assuming lower CPU number will be equivalent to lower a SMT thread
       number.

RETURN
       1 when packing is required and a task should be moved to this CPU. The amount of the
       imbalance is returned in *imbalance.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                     CHECK_ASYM_PACKING(9)