1CHECK_ASYM_PACKING(9)            Driver Basics           CHECK_ASYM_PACKING(9)
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NAME

6       check_asym_packing - Check to see if the group is packed into the sched
7       doman.
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SYNOPSIS

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

13       env
14           The load balancing environment.
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16       sds
17           Statistics of the sched_domain which is to be packed
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DESCRIPTION

20       This is primarily intended to used at the sibling level. Some cores
21       like POWER7 prefer to use lower numbered SMT threads. In the case of
22       POWER7, it can move to lower SMT modes only when higher threads are
23       idle. When in lower SMT modes, the threads will perform better since
24       they share less core resources. Hence when we have idle threads, we
25       want them to be the higher ones.
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27       This packing function is run on idle threads. It checks to see if the
28       busiest CPU in this domain (core in the P7 case) has a higher CPU
29       number than the packing function is being run on. Here we are assuming
30       lower CPU number will be equivalent to lower a SMT thread number.
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RETURN

33       1 when packing is required and a task should be moved to this CPU. The
34       amount of the imbalance is returned in *imbalance.
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37Kernel Hackers Manual 3.10         June 2019             CHECK_ASYM_PACKING(9)
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