centos man page for check_asym_packing

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 3.10					     June 2014						     CHECK_ASYM_PACKING(9)