[rescue] ss2 under load

[Joshua D Boyd]

On Thu, Feb 14, 2002 at 04:47:48PM -0500, Kurt Mosiejczuk wrote:
>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."
> 
>It goes on to say that if you stay under the number of HW contexts, it's
>actually faster than a TLB system (which is what most things use, including
>sparcs after the sun4c era).  But if you are on an IPX with 8 contexts and
>have like 16 active processes, it's got to start purging them out and loading
>the new active process.  Basically, it's an MMU cache =)

<snip>
 
>Hope this helps.  Granted, if you aren't at all familiar with how
>virtual memory works, you may just be more confused now... =)

Thanks.  That clears things up considerably.  So, which machine had the 64
contexts?

-- 
Joshua D. Boyd