Re: [GENERAL] Re: Multiple Indexing, performance impact

> At 05:56 PM 22-06-2001 -0400, Bruce Momjian wrote:
> >> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> Since 64 is already too much to let 7.1 fit in SHMMAX = 1MB, I think
> >> the original rationale for using 64 is looking pretty broken anyway.
> >> Comments?
> >
> >BSD/OS has a 4MB max but we document how to increase it by recompiling
> >the kernel.  Maybe if we fail the startup we can tell them how to
> >decrease the buffers in postgresql.conf file.  Seems quite clear.
> >
>
> Why is SHMMAX so low on some O/Ses? What are the advantages?
>
> My guess is it's a minimum vs median/popular situation. Get the same thing
> looking at the default www.kernel.org linux kernel settings vs the Redhat
> kernel settings.
>
> I'd personally prefer the popular situation. But would that mean the
> minimum case can't even boot up to recompile? Maybe the BSD guys should
> ship with two kernels then. FreeBSD esp, since it's easy to recompile the
> kernel, just do two, during installation default to "Regular", with an
> option for "Tiny".
>
> It's more fair that the people trying the extraordinary (16MB 386) should
> be the ones doing the extra work.

I think the problem is that with a default-sized kernel, the little guys
couldn't even boot the OS.  Also, some of the OS's hard-wire things into
the kernel for performance reasons.

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