Re: Multi CPU Queries - Feedback and/or suggestions wanted!

Greg Stark wrote:
> I couldn't get async I/O to work on Linux. That is it "worked" but
> performed the same as reading one block at a time. On solaris the
> situation is reversed.
>
> In what way is fadvise a kludge?

I think he is saying AIO gives us more flexibility, but I am unsure we
need it.

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>
> greg
>
> On 24 Oct 2008, at 01:44 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> > Jonah H. Harris wrote:
> >> On Thu, Oct 23, 2008 at 4:53 PM, Greg Smith <gsmith(at)gregsmith(dot)com>
> >> wrote:
> >>>> I think the current plan is to use posix_advise() to allow
> >>>> parallel I/O,
> >>>> rather than async I/O becuase posix_advise() will require fewer
> >>>> code
> >>>> changes.
> >>>
> >>> These are not necessarily mutually exclusive designs. fadvise
> >>> works fine on
> >>> Linux, but as far as I know only async I/O works on Solaris.
> >>> Linux also has
> >>> an async I/O library, and it's not clear to me yet whether that
> >>> might work
> >>> even better than the fadvise approach.
> >>
> >> fadvise is a kludge. While it will help, it still makes us
> >> completely
> >> reliant on the OS. For performance reasons, we should be
> >> supporting a
> >> multi-block read directly into shared buffers. IIRC, we currently
> >> have support for rings in the buffer pool, which we could read
> >> directly into. Though, an LRU-based buffer manager design would be
> >> more optimal in this case.
> >
> > True, it is a kludge but if it gives us 95% of the benfit with 10% of
> > the code, it is a win.
> >
> > --
> > Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
> > EnterpriseDB http://enterprisedb.com
> >
> > + If your life is a hard drive, Christ can be your backup. +
> >
> > --
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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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