From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | David Gilbert <dgilbert(at)velocet(dot)ca> |
Cc: | "Thomas O'Connell" <tfo(at)monsterlabs(dot)com>, pgsql-admin(at)postgresql(dot)org |
Subject: | Re: performance tuning: shared_buffers, sort_mem; swap |
Date: | 2002-08-14 13:41:01 |
Message-ID: | 7558.1029332461@sss.pgh.pa.us |
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Lists: | pgsql-admin |
David Gilbert <dgilbert(at)velocet(dot)ca> writes:
> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> Tom> Well, I must say this is the first time I've heard of "BSD-style
> Tom> shared memory".
> The canonical example is to mmap() a file multiply.
Oh. Yes, as Curt said, this issue has been beaten to death already;
see the archives.
You could in fact use a MAP_ANON region as a replacement for SysV shared
memory, but AFAICT you would lose a rather important interlock against
starting a new postmaster when old backends remain alive. Ugly as the
SysV API is, it does some things we need rather nicely.
> One bonus of bsd shared memory (when anonymous) is that it dies with
> the process ... even in the worst case.
But in fact we don't *want* it to be anonymous.
regards, tom lane
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