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authorNiklas Hambüchen <mail@nh2.me>2020-02-16 06:31:16 +0100
committerBen Gamari <ben@well-typed.com>2020-02-20 10:37:53 -0500
commit19680ee533bb95c0c5c42aca5c81197e4b233979 (patch)
tree9451506e3eaee02eac6e0b07336da45800079170 /docs
parentd53e81c02c64e72ccb55bf73f0881c5c80fa50ef (diff)
downloadhaskell-19680ee533bb95c0c5c42aca5c81197e4b233979.tar.gz
8.10 Release notes for --disable-delayed-os-memory-return [skip ci]
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+++ b/docs/users_guide/8.10.1-notes.rst
@@ -243,6 +243,21 @@ Runtime system
configure ``EventLogWriters``, allowing eventlog data to fed to sinks other
than ``.eventlog`` files.
+- A new ``+RTS`` flag ``--disable-delayed-os-memory-return`` was added to make
+ for accurate resident memory usage of the program as shown in memory
+ usage reporting tools (e.g. the ``RSS`` column in ``top`` and ``htop``).
+
+ This makes it easier to check the real memory usage of Haskell programs.
+
+ Using this new flag is expected to make the program slightly slower.
+
+ Without this flag, the (Linux) RTS returns unused memory "lazily" to the OS.
+ This has making the memory available to other processes while also allowing
+ the RTS to re-use the memory very efficiently (without zeroing pages) in case
+ it needs it again, but common tools will incorrectly show such memory as
+ occupied by the RTS (because they do not process the ``LazyFree`` field in
+ ``/proc/PID/smaps``).
+
Template Haskell
~~~~~~~~~~~~~~~~