Re: [Boost-users] container performance on 64 bit systems

From: Damien Hocking (damien_at_[hidden])
Date: 2007-09-21 13:41:41

I've had the same problem.  I ended up writing a key-based binary-sorted vector.  Same storage as a normal vector, but sorted and it's a bit faster than a std::map.

Damien
  _____  

From: Bruce Adams [mailto:tortoise_74_at_[hidden]]
To: boost-users_at_[hidden]
Sent: Fri, 21 Sep 2007 10:24:58 -0600
Subject: [Boost-users] container performance on 64 bit systems

  Hi,
     This may seem slightly off topic initially but bear
  with me. I have recently been having fun with the
  ordinary STL containers on a 64bit linux system. In
  particular the sorted associative containers set and
  map bloat the memory usage to an unacceptable level. 
  Part of this is down to 64 bit pointers versus 32 bit
  pointers.
  In a standard Red-Black tree implementation each node
  has 3 pointers, these double in size as do any
  pointers in the containers themselves. There are also
  issues with allocating on 8byte and 16byte boundaries.
  
  I measured and discovered that an otherwise highly
  efficient structure took *10* times as much memory on
  a 64bit machine vs. the 32bit one. I can half the
  memory usage for a std::set by replacing it with a
  std::vector and sorting it manually. Nothing too out
  of the ordinary there. 
  To solve my problem I have replaced a large number of
  64bit pointers with indices and manipulate
  std::vector's of these instead of using associative
  containers. 
  
  Are there any 'better' implementations of std::set
  etc. (preferably open source GNU/Linux compatible) out
  there? Are any planned?
  Does boost contain any suitable replacements?
  
  Does boost itself suffer from or tackle this 64bit
  bloat problem?
  
  Regards,
  
  Bruce.
  
  
         
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