Re: [HACKERS] posix_fadvise versus old kernels

2006-06-27 Thread Tom Lane
Bruce Momjian <[EMAIL PROTECTED]> writes:
> Tom Lane wrote:
>> 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.

Works for me; I'll write something and commit it.  We can leave the
is-posix_fadvise-declared configure test in place, at least for now ...

regards, tom lane

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Re: [HACKERS] posix_fadvise versus old kernels

2006-06-27 Thread Bruce Momjian
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.

-- 
  Bruce Momjian   [EMAIL PROTECTED]
  EnterpriseDBhttp://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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