From: Otto Moerbeek Date: Thu, 6 Jun 2024 11:55:34 +0000 (+0200) Subject: Apply suggestions from code review X-Git-Tag: rec-5.2.0-alpha0~30^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F14300%2Fhead;p=thirdparty%2Fpdns.git Apply suggestions from code review Co-authored-by: Remi Gacogne --- diff --git a/pdns/recursordist/docs/performance.rst b/pdns/recursordist/docs/performance.rst index 6668de07c3..c023c11ae0 100644 --- a/pdns/recursordist/docs/performance.rst +++ b/pdns/recursordist/docs/performance.rst @@ -89,11 +89,11 @@ To reduce the cost of allocating a new stack for every query, the recursor can c This limit is per physical (Posix) thread. The only trade-off of enabling this cache is a slightly increased memory consumption, at worst equals to the number of stacks specified by :ref:`setting-stack-cache-size` multiplied by the size of one stack, itself specified via :ref:`setting-stack-size`. -Linux limits the number of memory mappings a process can allocate by the the ``vm.max_map_count`` kernel parameter. -A single ``MThead`` stack can take up to 3 memory mappings. -Starting with version 4.9, it is advised to set ``sysctl vm.max_map_count`` to make sure that the :program:`Recursor` can allocate enough stacks under load; suggested value is at least ``4 * (threads + 2) * max-mthreads``. -Some Linux distributions use the value of about one million, which should be enough for most configurations. -Other distributions default to 64k, which can be too low. +Linux limits the number of memory mappings a process can allocate by the ``vm.max_map_count`` kernel parameter. +A single ``MThread`` stack can take up to 3 memory mappings. +Starting with version 4.9, it is advised to check and if needed update the value of ``sysctl vm.max_map_count`` to make sure that the :program:`Recursor` can allocate enough stacks under load; suggested value is at least ``4 * (threads + 2) * max-mthreads``. +Some Linux distributions use a default value of about one million, which should be enough for most configurations. +Other distributions default to 64k, which can be too low for large setups. Performance tips ----------------