On Mon, Aug 19, 2013 at 09:27:57PM -0400, Stephen Frost wrote:
* Andres Freund (andres@2ndquadrant.com) wrote:
I vote for adapting the patch to additionally zero out the file via
write(). In your tests that seemed to perform at least as good as the
old method... It also has the advantage that we can use it a littlebit
more as a testbed for possibly using it for heap extensions one day.
We're pretty early in the cycle, so I am not worried about this too much...
I dunno, I'm pretty disappointed that this doesn't actually improve
things. Just following this casually, it looks like it might be some
kind of locking issue in the kernel that's causing it to be slower; or
at least some code path that isn't exercise terribly much and therefore
hasn't been given the love that it should.

Definitely interested in what Ts'o says, but if we can't figure out why
it's slower *without* writing out the zeros, I'd say we punt on this
until Linux and the other OS folks improve the situation.
Agreed. Anyone with an affected kernel really can't be doing
performance tests right now, and that isn't good.

   Bruce Momjian <bruce@momjian.us> http://momjian.us
   EnterpriseDB http://enterprisedb.com

   + It's impossible for everything to be true. +

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