#!/bin/bash
#
# Get an estimate of how CPU-hoggy to be.
#
# Usage: cpus2use.sh
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you can access it online at
# http://www.gnu.org/licenses/gpl-2.0.html.
#
# Copyright (C) IBM Corporation, 2013
#
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

global ncpus := $[grep '^processor' /proc/cpuinfo | wc -l]
global idlecpus := $[mpstat | tail -1 | \
	awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }]
awk -v ncpus=$ncpus -v idlecpus=$idlecpus < /dev/null '
BEGIN {
	cpus2use = idlecpus;
	if (cpus2use < 1)
		cpus2use = 1;
	if (cpus2use < ncpus / 10)
		cpus2use = ncpus / 10;
	if (cpus2use == int(cpus2use))
		cpus2use = int(cpus2use)
	else
		cpus2use = int(cpus2use) + 1
	print cpus2use;
}< /dev/null '
BEGIN {
	cpus2use = idlecpus;
	if (cpus2use < 1)
		cpus2use = 1;
	if (cpus2use < ncpus / 10)
		cpus2use = ncpus / 10;
	if (cpus2use == int(cpus2use))
		cpus2use = int(cpus2use)
	else
		cpus2use = int(cpus2use) + 1
	print cpus2use;
}'

(CommandList
  children: [
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:ncpus)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: 
                  (CommandList
                    children: [
                      (Pipeline
                        children: [
                          (C {(grep)} {(SQ <"^processor">)} {(/proc/cpuinfo)})
                          (C {(wc)} {(-l)})
                        ]
                        negated: False
                      )
                    ]
                  )
                left_token: <Left_Backtick "`">
                spids: [71 85]
              )
            }
          spids: [70]
        )
      ]
      spids: [70]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:idlecpus)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: 
                  (CommandList
                    children: [
                      (Pipeline
                        children: [
                          (C {(mpstat)})
                          (C {(tail)} {(-1)})
                          (C {(awk)} {(-v)} {(Lit_VarLike "ncpus=") ($ VSub_Name "$ncpus")} 
                            {(SQ <"{ print ncpus * ($7 + $NF) / 100 }">)}
                          )
                        ]
                        negated: False
                      )
                    ]
                  )
                left_token: <Left_Backtick "`">
                spids: [88 111]
              )
            }
          spids: [87]
        )
      ]
      spids: [87]
    )
    (SimpleCommand
      words: [
        {(awk)}
        {(-v)}
        {(Lit_VarLike "ncpus=") ($ VSub_Name "$ncpus")}
        {(-v)}
        {(Lit_VarLike "idlecpus=") ($ VSub_Name "$idlecpus")}
        {
          (SQ <"\n"> <"BEGIN {\n"> <"\tcpus2use = idlecpus;\n"> <"\tif (cpus2use < 1)\n"> 
            <"\t\tcpus2use = 1;\n"> <"\tif (cpus2use < ncpus / 10)\n"> <"\t\tcpus2use = ncpus / 10;\n"> 
            <"\tif (cpus2use == int(cpus2use))\n"> <"\t\tcpus2use = int(cpus2use)\n"> <"\telse\n"> <"\t\tcpus2use = int(cpus2use) + 1\n"> 
            <"\tprint cpus2use;\n"> <"}">
          )
        }
      ]
      redirects: [(Redir op_id:Redir_Less fd:-1 arg_word:{(/dev/null)} spids:[125])]
    )
  ]
)