'\" t
.\"     Title: check_asym_packing
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Driver Basics
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "CHECK_ASYM_PACKING" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Driver Basics"
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.SH "NAME"
check_asym_packing \- Check to see if the group is packed into the sched doman\&.
.SH "SYNOPSIS"
.HP \w'int\ check_asym_packing('u
.BI "int check_asym_packing(struct\ lb_env\ *\ " "env" ", struct\ sd_lb_stats\ *\ " "sds" ");"
.SH "ARGUMENTS"
.PP
\fIenv\fR
.RS 4
The load balancing environment\&.
.RE
.PP
\fIsds\fR
.RS 4
Statistics of the sched_domain which is to be packed
.RE
.SH "DESCRIPTION"
.PP
.PP
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\&.
.PP
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\&.
.SH "RETURN"
.PP
1 when packing is required and a task should be moved to this CPU\&. The amount of the imbalance is returned in *imbalance\&.
.SH "COPYRIGHT"
.br