On Monday, March 24, 2003, at 06:32 PM, der Mouse wrote:
>>>>> [...two-KA630 speculation...]
>>>> [...] multiple [KA630] processors do NOT share main memory.
>>> They do if they want...with some restrictions.  [...via Qbus...]
>> This brings up an interesting possibility.  Processes that have
>> multiple threads (i.e. that would take advantage of multiple
>> processors) could have their virtual addresses mapped by the VM
>> system to physical addresses in the "shareable" space.
>
> They'd have to be fairly small, or else they'd be taking tons of
> pagefaults to swap pages in and out of the relatively small window the
> Qbus allows.

   Yup.  I was just throwing it out as an interesting and possibly fun 
idea, not a particularly practical one.

> Also, on all but one of the processors, they'd be paying a speed
> penalty, and from what I recall a fairly hefty one.

   Yes...Qbus tops out at 3.3MB/s if memory serves, then there's any 
latency incurred by the arbitration logic on the CPU. :-(

        -Dave

--
Dave McGuire             "I've grown hair again, just
St. Petersburg, FL           for the occasion."       -Doc Shipley