[rescue] ss2 under load

[Patrick Giagnocavo]

On Thu, Feb 14, 2002 at 04:47:48PM -0500, Kurt Mosiejczuk wrote:
> On Thu, 14 Feb 2002, Joshua D Boyd wrote:
> 
> > > The 2 and the IPX are almost equivalent.  The main difference is the IPX
> > > has 8 hardware contexts and the 2 has 16.  Other than that, they are
> > > almost identical architecture wise.
> 
> > I'm not exactly sure what those hardware contexts are (is that the number of
> > windows in the register file?), but I was under the impression that more meant
> > better under heavy load.
> 
> Okay, you made me look it up in a book =)
> 
> To quote Sun Performance and Tuning (2d edition) by Adrian Cockroft:
> (page 267)
> 
> "A hardware context can be thought of as a tag on each PMEG entry in the MMU
> that indicates which process that translation is valid for.  The tag allows
> the MMU to keep track of the mappings for 8, 16 or 64 processes in the MMU,
> depending on the machine.  Then a context switch occurs, if the new process
> is already assigned to one of the hardware contexts, then some of its mappings
> may still be in the MMU and a very fast context switch can take place."
> 
> And for those who are acronym impaired:
> 
> MMU = Memory Management Unit
> PMEG = Page Map Entry Group

Thank goodness they kept to a flat 32bit memory model without any of
the x86 segmented memory crap.

Otherwise you would have a Segmented Map Entry Group and you would
have SMEG and if you had a SMEG memory access...

./patrick