kaspergrubbe · July 26, 2022 18:47 · Jul 26, 2022
diff --git a/jemalloc5.rb b/jemalloc5.rb
@@ -0,0 +1,31 @@
+# Inspiration: https://twitter.com/wgjordan/status/1440574986264006659
+
+jemalloc_conf = {
+  # Maximum number of arenas to use for automatic multiplexing of threads and arenas.
+  # The default is four times the number of CPUs, or one if there is a single CPU.
+  narenas: 2,
+
+  # Enabling jemalloc background threads generally improves the tail latency for application threads,
+  # since unused memory purging is shifted to the dedicated background threads.
+  # In addition, unintended purging delay caused by application inactivity is avoided with background threads.
+  #
+  # Suggested: background_thread:true when jemalloc managed threads can be allowed.
+  background_thread: true, # default false
+
+  # Transparent hugepage (THP) mode.
+  # Settings "always", "never" and "default" are available if THP is supported by the operating system.
+  # The "always" setting enables transparent hugepage for all user memory mappings with MADV_HUGEPAGE;
+  # "never" ensures no transparent hugepage with MADV_NOHUGEPAGE; the default setting "default" makes no changes.
+  thp: 'never',
+
+  # Decay time determines how fast jemalloc returns unused pages back to the operating system,
+  # and therefore provides a fairly straightforward trade-off between CPU and memory usage.
+  # Shorter decay time purges unused pages faster to reduces memory usage
+  # (usually at the cost of more CPU cycles spent on purging), and vice versa.
+  #
+  # Suggested: tune the values based on the desired trade-offs.
+  dirty_decay_ms: 1_000, # Default 10_000
+  muzzy_decay_ms: 0 # Default 10_000
+}.map {|x| x.join(':')}.join(',')
+
+# MALLOC_CONF="narenas:2,background_thread:true,thp:never,dirty_decay_ms:1000,muzzy_decay_ms:0"