Re: ShmemAlloc() alignment patch

Tom Lane wrote:
> Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> > On Fri, Jul 14, 2006 at 02:50:31PM +0800, Qingqing Zhou wrote:
> >> Notice that though newStart is ALIGNOF_BUFFER, ShmemBase is not. Thus the
> >> newSpace is not aligned as we disired.
>
> > How can ShmemBase not be aligned? Surely it's page-aligned?
>
> That's certainly what the code expects. I'm disinclined to apply this
> patch unless you can identify a real system where ShmemBase might not
> point to a page boundary.
>
> (Note: in a standalone backend, the "shared memory segment" is just a
> huge malloc chunk, and so depending on your platform it might not be
> page-aligned. I don't feel a need to add cycles to ShmemAlloc to
> optimize this case, though. We only care about performance in the
> normal shared-memory case.)

Should we add an assert?

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Bruce Momjian bruce(at)momjian(dot)us
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