PostgreSQL benchmarks (now with Linux numbers)

[Vlad Galu]

On Thu, Feb 23, 2012 at 2:41 PM, Damien Fleuriot <ml at my.gd> wrote:

>
>
> On 2/23/12 2:22 PM, John Baldwin wrote:
> > On Wednesday, February 22, 2012 9:59:02 pm Doug Barton wrote:
> >> On 02/22/2012 01:42, Ivan Voras wrote:
> >>> The Dragonfly team has recently liberated their VM from the giant lock
> and there are some interesting benchmarks comparing it to FreeBSD 9 and a
> > derivative of RedHat Enterprise Linux:
> >>>
> >>> http://leaf.dragonflybsd.org/mailarchive/kernel/2011-11/msg00008.html
> >>>
> >>> Other developments are described in their release notes:
> http://www.dragonflybsd.org/release30/
> >>
> >> The 4.5 times improvement by enabling kern.ipc.shm_use_phys is pretty
> >> notable, what prevents us from enabling that by default?
> >
> > It makes all your SYSV SHMs wired.  That's fine if you are running a
> dedicated
> > server using SYSV SHMs where you want that process to use all the RAM in
> the
> > machine (e.g. a pgqsl server).  It's not so great for a general purpose
> load
> > where you would like an otherwise-idle process using SYSV SHMs to have
> the SHMs
> > paged out to swap if other processes on the machine need memory and the
> box is
> > under memory pressure.
> >
>
> John, any chance we can get that in layman's terms ?
>
> I'm totally no coder, but I'd really like if we could do this at my work
> place to increase our firewalls' performances.
>

Hi Damien,

The above setting prevents the SYSV shared memory from being swapped by the
pager. It is useful in a database context, where you want the pages to be
available imediately, without having to wait until they are loaded back
from disk (in a memory constrained environment). I won't help your firewall
at all.


-- 
Good, fast & cheap. Pick any two.