puppet: Add vm sysctl settings to Postgres configs

(imported from commit e557815f490a603da635fb60d39569346a72aa85)

servers/puppet/modules/humbug/files/postgresql/30-postgresql-shm.conf.master

@@ -1,13 +0,0 @@
-# Shared memory settings for PostgreSQL
-
-# Note that if another program uses shared memory as well, you will have to
-# coordinate the size settings between the two.
-
-# Maximum size of shared memory segment in bytes
-#kernel.shmmax = 33554432
-
-# Maximum total size of shared memory in pages (normally 4096 bytes)
-#kernel.shmall = 2097152
-
-kernel.shmall = 6553600
-kernel.shmmax = 26843545600

servers/puppet/modules/humbug/files/postgresql/40-postgresql.conf.master

@@ -0,0 +1,16 @@
+# Shared memory settings
+
+# Maximum total size of shared memory in pages (normally 4096 bytes)
+kernel.shmall = 6553600
+# Maximum size of shared memory segment in bytes
+kernel.shmmax = 26843545600
+
+# Virtual memory settings
+vm.swappiness = 0
+vm.overcommit_memory = 2
+
+# We don't want these numbers to be too large or else performance
+# will be too spiky.  These seem to give a good balance between low
+# numbers and sequential write performance
+vm.dirty_ratio = 5
+vm.dirty_background_ratio = 2

servers/puppet/modules/humbug/files/postgresql/40-postgresql.conf.slave

@@ -1,13 +1,14 @@
 # Shared memory settings for PostgreSQL
 
-# Note that if another program uses shared memory as well, you will have to
-# coordinate the size settings between the two.
-
-# Maximum size of shared memory segment in bytes
-#kernel.shmmax = 33554432
-
 # Maximum total size of shared memory in pages (normally 4096 bytes)
-#kernel.shmall = 2097152
-
 kernel.shmall = 1703936
+# Maximum size of shared memory segment in bytes
 kernel.shmmax = 6979321856
+
+# Virtual memory settings
+vm.swappiness = 0
+vm.overcommit_memory = 2
+
+# These are the defaults on newer kernels
+vm.dirty_ratio = 10
+vm.dirty_background_ratio = 5

servers/puppet/modules/humbug/manifests/postgres-common.pp

@@ -14,8 +14,8 @@ class humbug::postgres-common {
   }
 
   exec { "sysctl_p":
-    command   => "/sbin/sysctl -p /etc/sysctl.d/30-postgresql-shm.conf",
-    subscribe => File['/etc/sysctl.d/30-postgresql-shm.conf'],
+    command   => "/sbin/sysctl -p /etc/sysctl.d/40-postgresql.conf",
+    subscribe => File['/etc/sysctl.d/40-postgresql.conf'],
     refreshonly => true,
   }
 

servers/puppet/modules/humbug/manifests/postgres-master.pp

@@ -4,12 +4,17 @@ class humbug::postgres-master {
   $master_packages = [ "xfsprogs", "mdadm", ]
   package { $master_packages: ensure => "installed" }
 
+  # We bundle a bunch of other sysctl parameters into 40-postgresql.conf
   file { '/etc/sysctl.d/30-postgresql-shm.conf':
+    ensure => absent,
+  }
+
+  file { '/etc/sysctl.d/40-postgresql.conf':
     ensure => file,
     owner  => 'root',
     group  => 'root',
     mode   => 644,
-    source   => 'puppet:///modules/humbug/postgresql/30-postgresql-shm.conf.master',
+    source   => 'puppet:///modules/humbug/postgresql/40-postgresql.conf.master',
   }
 
   file { "/etc/postgresql/9.1/main/postgresql.conf":

servers/puppet/modules/humbug/manifests/postgres-slave.pp

@@ -1,12 +1,17 @@
 class humbug::postgres-slave {
   class { 'humbug::postgres-common': }
 
+  # We bundle a bunch of other sysctl parameters into 40-postgresql.conf
   file { '/etc/sysctl.d/30-postgresql-shm.conf':
+    ensure => absent,
+  }
+
+  file { '/etc/sysctl.d/40-postgresql.conf':
     ensure => file,
     owner  => 'root',
     group  => 'root',
     mode   => 644,
-    source   => 'puppet:///modules/humbug/postgresql/30-postgresql-shm.conf.slave',
+    source   => 'puppet:///modules/humbug/postgresql/40-postgresql.conf.slave',
   }
 
   file { "/etc/postgresql/9.1/main/postgresql.conf":