Re: shared memory in computational chemistry
On Sat, 2007-04-07 at 18:53 +0100, Dave Ewart wrote:
> On Saturday, 07.04.2007 at 12:08 -0400, Greg Folkert wrote:
>
> > On Sat, 2007-04-07 at 16:06 +0100, Dave Ewart wrote:
> > > On Friday, 06.04.2007 at 15:39 -0700, Francesco Pietra wrote:
> > >
> > > > 1) How to set shmmax in debian?
> > >
> > > For the running kernel, echo a value to /proc/sys/kernel/shmmax - to
> > > make it a permanent setting (i.e. set automatically at subsequent
> > > reboots), include the setting in /etc/sysctl.conf:
> > >
> > > kernel.shmmax=whatever
> >
> > Umm, shmmax is auto-adjusted now in the 2.6 kernel. This is not the
> > real reason he is having difficulty.
>
> Hmm, since which kernel version, out of interest?
>
> The reason I ask is that I found it necessary to set SHMMAX for an AMD64
> Sarge machine with 16GB RAM running as a PostgreSQL database server and
> improved performance significantly as a result. For compatability
> reasons with the hardware, I couldn't use the most recent kernel: it's
> running 2.6.12.
See my other reply to Francesco, I went through the Kernel Docs and the
code... discovered it is auto-set at boot, but changeable. There was
some serious work being dome on these parameters being auto-adjusting,
but I see that it is not in any of the VM or semaphore controls, using
the defaults engines.
--
greg, greg@gregfolkert.net
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