Re: Pre-allocation of shared memory ... - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Pre-allocation of shared memory ...
Date
Msg-id 200306130211.h5D2Bdp27886@candle.pha.pa.us
Whole thread Raw
In response to Re: Pre-allocation of shared memory ...  (Greg Stark <gsstark@mit.edu>)
Responses Re: Pre-allocation of shared memory ...
List pgsql-hackers
Greg Stark wrote:
> I suspect this was less of an issue in the days before copy on write because
> vfork was more widely used/implemented. I'm not sure linux even implements
> vfork other than just as a wrapper around fork. Even BSD ditched it a while
> back though I think I saw that NetBSD reimplemented it since then.
> 
> > But then there's the problem of people running database servers on
> > misconfigured machines.  They should know better than not setting enough
> > swap space, IMHO anyway.
> 
> Well, I've seen DBAs say "Since I don't want the database swapping anyways,
> I'll make really sure it doesn't swap by just not giving it any swap space --
> that's why we bought so much RAM in the first place". It's not obvious that
> you need swap to back memory the machine doesn't even report as being in
> use...

I see no reason RAM can't be used as backing store for possible
copy-on-write use.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
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