Re: dynamically allocating chunks from shared memory

On Thu, Jul 22, 2010 at 3:09 PM, Markus Wanner <markus@bluegap.ch> wrote:
>> FWIW I don't think you should be thinking in "replacing imessages with
>> SLRU".  I rather think you should be thinking in how can you implement
>> the imessages API on top of SLRU.
>
> Well, I'm rather comparing SLRU with the dynamic allocator. So far I'm
> unconvinced that SLRU would be a better base for imessages than a dynamic
> allocator. (And I'm arguing that SLRU should use a dynamic allocator
> underneath).

Here's another idea.  Instead of making imessages use an SLRU, how
about having it steal pages from shared_buffers?  This would require
segmenting messages into small enough chunks that they'd fit, but the
nice part is that it would avoid the need to have a completely
separate shared memory arena.  Ideally, we'd make the infrastructure
general enough that things like SLRU could use it also; and get rid of
or reduce in size some of the special-purpose chunks we're now
allocating.

-- 
Robert Haas
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