6f6267ce29
This commit introduces a hugepages configuration for postgres via a rhizome lib+bin. At the moment, it uses the default huge page size (2M), and calculates the number of huge pages as 25% of the total available memory. The setup adjusts the shared_buffers accordingly to fit the shared memory within the allocated number of hugepages. The configuration happens as an `ExecStartPre` script added to the existing systemd unit managed by pg_ctlcluster. To keep the semantics of the `start` command unchanged, the hugepages script *does not* stop an existing cluster to configure hugepages, and only does it when the cluster is not running. In a subsequent change, we can consider adding the boot parameters to setup 1G hugepages for larger instances (possibly standard-30+), where they are most useful. [1]: https://www.postgresql.org/docs/current/kernel-resources.html#LINUX-HUGE-PAGES
74 lines
2.2 KiB
Ruby
74 lines
2.2 KiB
Ruby
# frozen_string_literal: true
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require_relative "../../common/lib/util"
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require "logger"
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class HugepagesSetup
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def initialize(instance, logger)
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@version, @cluster = instance.split("-", 2)
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@logger = logger
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end
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def get_postgres_param(param)
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Integer(r("sudo -u postgres /usr/lib/postgresql/#{@version.shellescape}/bin/postgres -D /dat/#{@version.shellescape}/data -c config_file=/etc/postgresql/#{@version.shellescape}/#{@cluster.shellescape}/postgresql.conf -C #{param.shellescape}"), 10)
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end
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def hugepage_info
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meminfo = File.read("/proc/meminfo")
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hugepages_count = Integer(meminfo[/^HugePages_Total:\s*(\d+)/, 1], 10)
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hugepage_size_kib = Integer(meminfo[/^Hugepagesize:\s*(\d+)\s*kB/, 1], 10)
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[hugepages_count, hugepage_size_kib]
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end
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def stop_postgres_cluster
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r "sudo pg_ctlcluster stop #{@version} #{@cluster}", expect: [0, 2] # 2 is "not running"
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end
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def setup_postgres_hugepages
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hugepages_count, hugepage_size_kib = hugepage_info
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if hugepages_count == 0
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@logger.warn("No hugepages configured, skipping setup.")
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return
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end
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hugepages_kib = hugepages_count * hugepage_size_kib
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update_postgres_hugepages_conf(hugepages_kib)
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shmem_and_overhead_kib = 1024 * get_postgres_param("shared_memory_size")
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overhead = shmem_and_overhead_kib - hugepages_kib
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target_kib = hugepages_kib - overhead
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# Floor division to nearest multiple of block_size: (a / b) * b
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block_size_bytes = get_postgres_param("block_size")
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block_size_kib = block_size_bytes / 1024
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final_shared_buffers_kib = (target_kib / block_size_kib) * block_size_kib
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update_postgres_hugepages_conf(final_shared_buffers_kib)
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end
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def update_postgres_hugepages_conf(shared_buffers_kib)
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safe_write_to_file("/etc/postgresql/#{@version}/#{@cluster}/conf.d/002-hugepages.conf", <<CONF
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huge_pages = 'on'
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huge_page_size = 0
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shared_buffers = #{shared_buffers_kib}kB
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CONF
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)
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end
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def postgres_running?
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r "sudo pg_ctlcluster status #{@version} #{@cluster}", expect: [3]
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false
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rescue CommandFail
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true
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end
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def setup
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unless postgres_running?
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stop_postgres_cluster
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setup_postgres_hugepages
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end
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end
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end
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