From 2a9d9642eaa7775a716166f1b9fc564e60c06b84 Mon Sep 17 00:00:00 2001
From: Roland Olbricht <roland.olbricht@gmx.de>
Date: Fri, 4 Nov 2022 21:29:43 +0100
Subject: [PATCH] Inform the OS cache with madvise

---
 src/template_db/file_blocks.h       | 1 +
 src/template_db/file_blocks_index.h | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/template_db/file_blocks.h b/src/template_db/file_blocks.h
index 134abf1a6..4b8c74eeb 100644
--- a/src/template_db/file_blocks.h
+++ b/src/template_db/file_blocks.h
@@ -794,6 +794,7 @@ class Mmap
       addr = mmap(0, length, PROT_READ, MAP_PRIVATE, fd, offset);
     if (addr == (void*)(-1))
       throw File_Error(errno, file_name, origin);
+    posix_madvise(addr, length, POSIX_MADV_WILLNEED);
   }
   ~Mmap()
   { 
diff --git a/src/template_db/file_blocks_index.h b/src/template_db/file_blocks_index.h
index 4ef279203..3b5cd211d 100644
--- a/src/template_db/file_blocks_index.h
+++ b/src/template_db/file_blocks_index.h
@@ -206,7 +206,7 @@ struct Readonly_File_Blocks_Index : public File_Blocks_Index_Base
   void increase_block_count(uint32 delta) { params.block_count += delta; }
   virtual bool empty() const { return params.empty_; }
   File_Blocks_Index_Iterator< Index > begin()
-  { //std::cout<<"DEBUG File_Blocks_Idx "<<(void*)idx_file.begin()<<' '<<(void*)idx_file.end()<<' '<<data_file_name<<'\n';
+  { posix_madvise((void*)idx_file.header(), idx_file.size(), POSIX_MADV_WILLNEED);
     return File_Blocks_Index_Iterator< Index >(idx_file.begin(), idx_file.end()); }
   File_Blocks_Index_Iterator< Index > end()
   { return File_Blocks_Index_Iterator< Index >(idx_file.end(), idx_file.end()); }