libraries/swap_tuning.rb
# encoding: UTF-8
#
# Cookbook Name:: swap_tuning
# Library:: swap_tuning
# Author:: Xabier de Zuazo (<xabier@zuazo.org>)
# Copyright:: Copyright (c) 2014 Onddo Labs, SL.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
require 'chef/application'
class Chef
# Methods to recommend swap sizes depending on memory values
module SwapTuning
SIZE_UNITS = {
'GB' => 1_073_741_824,
'MB' => 1_048_576,
'KB' => 1024,
'B' => 1
} unless defined?(::Chef::SwapTuning::SIZE_UNITS)
def self.memory2bytes(memory)
case memory.to_s
when /^([0-9]+)([GMK]?B)$/i
Regexp.last_match[1].to_i * SIZE_UNITS[Regexp.last_match[2].upcase]
when /^([0-9]+)$/i then Regexp.last_match[1].to_i
else fail "Unknown size: #{memory}"
end
end
def self.memory2mbytes(memory)
memory2bytes(memory).to_f / SIZE_UNITS['MB']
end
def self.memory2gbytes(memory)
memory2mbytes(memory) / SIZE_UNITS['KB']
end
def self.unknown_size_check(memory)
Chef::Log.warn(
"RAM size too high (#{memory2gbytes(memory).round} GB), "\
'I may not be able to choose the best swap size. Best size will be '\
'workload dependent.'
) if memory > 68_719_476_736 # 64 GB
end
def self.recommended_size_bytes(memory)
memory_b = memory2bytes(memory)
unknown_size_check(memory_b)
if memory_b <= 2_147_483_648 # 2 GB
memory_b * 2
elsif memory_b <= 8_589_934_592 # 8 GB
memory_b
else
(memory_b.to_f / 2).ceil
end
end
def self.recommended_size_mb(memory)
bytes = recommended_size_bytes(memory)
(bytes.to_f / 1_048_576).ceil
end
end
end