Re: posix_fadvise versus old kernels

Tom Lane wrote:
> I've been digging into why buildfarm member thrush has been dumping core
> consistently during the regression tests since the posix_fadvise patch
> went in. I've confirmed that posix_fadvise() itself will SIGSEGV in a
> standalone test program, and found that this happens only if
> _FILE_OFFSET_BITS=64 ... which is our default configuration on Linux.
>
> Some googling turned up the following
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=313219
> which basically says that posix_fadvise64 + 2.4 kernel + older glibc
> = crash. It sounds like the 2.4 kernel hasn't got this call but glibc
> thought it did, up till about a year ago.
>
> While we could possibly come up with a suitable configure test to
> determine whether posix_fadvise is actually safe to use on a given
> system, I think we should seriously consider just reverting the patch.
> As far as I saw, zero evidence was given that it actually does anything
> measurable. Without a benchmark to prove that it's worth spending more
> time on, I'm disinclined to trouble over it.

Agreed. How about if we just #ifdef NOT_USED the code and mention the
problem in a comment.

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Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

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