From d55d1aa4d7c782d1dc1be60ef241c74b46186988 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Catherine=20Sch=C3=B6fmann?= <c.schoefmann@fz-juelich.de>
Date: Sat, 24 Feb 2024 01:59:37 +0100
Subject: [PATCH 1/3] Attempt cache thrashing fix

---
 nestkernel/connection_manager.cpp |  2 +-
 nestkernel/connection_manager.h   | 17 ++++++++++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/nestkernel/connection_manager.cpp b/nestkernel/connection_manager.cpp
index 7345f07193..bc050ff78a 100644
--- a/nestkernel/connection_manager.cpp
+++ b/nestkernel/connection_manager.cpp
@@ -131,7 +131,7 @@ nest::ConnectionManager::initialize( const bool reset_kernel )
   std::vector< DelayChecker > tmp( kernel().vp_manager.get_num_threads() );
   delay_checkers_.swap( tmp );
 
-  std::vector< std::vector< size_t > > tmp2( kernel().vp_manager.get_num_threads(), std::vector< size_t >() );
+  std::vector<aligned_vector<size_t>> tmp2( kernel().vp_manager.get_num_threads(), aligned_vector<size_t>() );
   num_connections_.swap( tmp2 );
 }
 
diff --git a/nestkernel/connection_manager.h b/nestkernel/connection_manager.h
index 315e2a1305..84e6516547 100644
--- a/nestkernel/connection_manager.h
+++ b/nestkernel/connection_manager.h
@@ -30,6 +30,11 @@
 #include "manager_interface.h"
 #include "stopwatch.h"
 
+#ifdef HAVE_BOOST
+#include <new>
+#include <boost/align/aligned_allocator.hpp>
+#endif
+
 // Includes from nestkernel:
 #include "conn_builder.h"
 #include "connection_id.h"
@@ -52,6 +57,15 @@
 
 namespace nest
 {
+
+#ifdef HAVE_BOOST
+  template <typename T>
+  using aligned_vector = std::vector< T, boost::alignment::aligned_allocator<T, std::hardware_destructive_interference_size> >;
+#else
+  template <typename T>
+  using aligned_vector = std::vector<T>;
+#endif
+
 class GenericConnBuilderFactory;
 class spikecounter;
 class Node;
@@ -633,7 +647,8 @@ class ConnectionManager : public ManagerInterface
    * A structure to count the number of synapses of a specific
    * type. Arranged in a 2d structure: threads|synapsetypes.
    */
-  std::vector< std::vector< size_t > > num_connections_;
+
+  std::vector<aligned_vector<size_t>> num_connections_;
 
   DictionaryDatum connruledict_; //!< Dictionary for connection rules.
 

From 720e9d9422fda124a5b4e5e9b8b5482a43497377 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Catherine=20Sch=C3=B6fmann?= <c.schoefmann@fz-juelich.de>
Date: Sat, 24 Feb 2024 19:41:42 +0100
Subject: [PATCH 2/3] Run clang-format

---
 nestkernel/connection_manager.cpp |  2 +-
 nestkernel/connection_manager.h   | 13 +++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/nestkernel/connection_manager.cpp b/nestkernel/connection_manager.cpp
index bc050ff78a..1042b45122 100644
--- a/nestkernel/connection_manager.cpp
+++ b/nestkernel/connection_manager.cpp
@@ -131,7 +131,7 @@ nest::ConnectionManager::initialize( const bool reset_kernel )
   std::vector< DelayChecker > tmp( kernel().vp_manager.get_num_threads() );
   delay_checkers_.swap( tmp );
 
-  std::vector<aligned_vector<size_t>> tmp2( kernel().vp_manager.get_num_threads(), aligned_vector<size_t>() );
+  std::vector< aligned_vector< size_t > > tmp2( kernel().vp_manager.get_num_threads(), aligned_vector< size_t >() );
   num_connections_.swap( tmp2 );
 }
 
diff --git a/nestkernel/connection_manager.h b/nestkernel/connection_manager.h
index 84e6516547..fb33d9688b 100644
--- a/nestkernel/connection_manager.h
+++ b/nestkernel/connection_manager.h
@@ -31,8 +31,8 @@
 #include "stopwatch.h"
 
 #ifdef HAVE_BOOST
-#include <new>
 #include <boost/align/aligned_allocator.hpp>
+#include <new>
 #endif
 
 // Includes from nestkernel:
@@ -59,11 +59,12 @@ namespace nest
 {
 
 #ifdef HAVE_BOOST
-  template <typename T>
-  using aligned_vector = std::vector< T, boost::alignment::aligned_allocator<T, std::hardware_destructive_interference_size> >;
+template < typename T >
+using aligned_vector =
+  std::vector< T, boost::alignment::aligned_allocator< T, std::hardware_destructive_interference_size > >;
 #else
-  template <typename T>
-  using aligned_vector = std::vector<T>;
+template < typename T >
+using aligned_vector = std::vector< T >;
 #endif
 
 class GenericConnBuilderFactory;
@@ -648,7 +649,7 @@ class ConnectionManager : public ManagerInterface
    * type. Arranged in a 2d structure: threads|synapsetypes.
    */
 
-  std::vector<aligned_vector<size_t>> num_connections_;
+  std::vector< aligned_vector< size_t > > num_connections_;
 
   DictionaryDatum connruledict_; //!< Dictionary for connection rules.
 

From 46d21cfe3efff85a2173946ffea3dd892414fc40 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Catherine=20Sch=C3=B6fmann?= <c.schoefmann@fz-juelich.de>
Date: Sat, 24 Feb 2024 20:32:59 +0100
Subject: [PATCH 3/3] Add feature version test

---
 nestkernel/connection_manager.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/nestkernel/connection_manager.h b/nestkernel/connection_manager.h
index fb33d9688b..512af11ab5 100644
--- a/nestkernel/connection_manager.h
+++ b/nestkernel/connection_manager.h
@@ -31,6 +31,11 @@
 #include "stopwatch.h"
 
 #ifdef HAVE_BOOST
+#ifdef __cpp_lib_hardware_interference_size
+using std::hardware_destructive_interference_size;
+#else
+constexpr std::size_t hardware_destructive_interference_size = 64;
+#endif
 #include <boost/align/aligned_allocator.hpp>
 #include <new>
 #endif
@@ -61,7 +66,7 @@ namespace nest
 #ifdef HAVE_BOOST
 template < typename T >
 using aligned_vector =
-  std::vector< T, boost::alignment::aligned_allocator< T, std::hardware_destructive_interference_size > >;
+  std::vector< T, boost::alignment::aligned_allocator< T, hardware_destructive_interference_size > >;
 #else
 template < typename T >
 using aligned_vector = std::vector< T >;