Re: dynamically allocating chunks from shared memory

Bruce Momjian <bruce@momjian.us>

From: Bruce Momjian <bruce@momjian.us>
To: Markus Wanner <markus@bluegap.ch>
Cc: Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera <alvherre@commandprompt.com>, PostgreSQL-development Hackers <pgsql-hackers@postgresql.org>
Date: 2010-08-09T18:33:08Z
Lists: pgsql-hackers
Markus Wanner wrote:
> Hi,
> 
> On 08/09/2010 06:10 PM, Bruce Momjian wrote:
> > My point is that you can treat malloc the same as "add shared memory",
> > to some extent, with the same limiations.
> 
> Once one of the SLRU buffers is full, it cannot currently allocate from 
> another SLRU buffer's unused memory area. That memory there is plain 
> wasted at that moment. That's my point and the problem the allocator I 
> posted tries to solve.
> 
> I fail to see how malloc could help here. malloc() only allocates 
> process-local memory.

My point is that we have the same limitations with malloc()/threads, as
we have with shared memory.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +