It's also worth pointing out that some database servers statically link
their binaries to remove shared libraries from the "middle" of the address
space.  This should give you considerably more.

- Peter -


On Tue, 18 Jan 2000, Jan Harkes wrote:

> On Tue, Jan 18, 2000 at 10:37:40AM -0800, Phil Nelson wrote:
> > 
> > >I just wish to know what is the optimum configuration I can have on a
> > >42G Raid drive. I have 256M of RAM and a local SCSI drive of 9G and
> > >an external RAID of 42 GBHDD. Its a PIII500MMX IBM Box. /vicepa will
> > >be on the external raid while the rest on the local drive.
> > > For a 42GHDD , I need about 1.7G of RVM according to the 4% rule and what
> > >about the Log size? Does my swap partition plays a part here for the RVM??
> > >How much space should I allocate?
> > >
> > >With 1.7G of RVM , do I need to run rdsinit instead of vice-setup-rvm??
> > 
> > I haven't heard of a server of this size yet.  Since is is not one of
> > the standard setups in vice-setup-rvm, you would have to init RVM yourself.
> > I did it for a 6G server (also not one of the standard sizes.)
> > 
> > A big problem you may have is the startup time with such a large RVM, IF 
> > you have enough VM space to map it in the first place.  This can be helped
> > by using a relatively new flag, "-mapprivate", for the server.  I believe
> > it is in coda 5.3.4, but I'm not sure.
> 
> Yes mapprivate is available in the 5.3.4 release. One caveat, it only
> works when RVM is stored in a file.
> 
> You actually need to play with the address where rvm is mapped. We
> currently map it at 0x20000000. Linux places shared libraries and other
> memory mapped files at 0x40000000, which limits the usable area for RVM
> to about 512MB.
> 
> By moving the address where RVM is mapped to 0x41000000, you'll put it
> above the libraries where there is room to 0xbff00000 before you hit the
> stack. That gives about 2031MB of available space.
> 
> Check /proc/`pidof codasrv`/maps to see how the memory map is layed out.
> 
> Jan
>