On Wed, 02 Jan 2008 20:51:35 +0000, Norman Dunbar wrote > Hi Dave, > > Dave Walker wrote: > > > Modern machines have hyperthreaded CPU cores, so you are more > > likely > > to load multiple applications and still get decent performance if > > you have lots of memory available. > > A good theory, in practice it is let down by either the > design of the Core Duo chip or the OS not utilising things > properly - I'm not sure which. > > In a Core Duo, all accesses to the Input Output sub-systems > *must* be done by the first core and only by the first core. > I read this about a month ago in one of the mainstream > computer comics - can't remember which one now that I need to. > > Apparently, core 1 says to core 0, stop that and service > this I/O request for me, so core 0 has to comply, so > anything running on the first core is interrupted while it > passes on I/O requests for the second core, and the second > core is delayed in processing I/O while it hangs around > waiting for the first core to pay attention! > > An interesting design I thought when I read it. > > Cheers, > Norman. > _______________________________________________ > QL-Users Mailing List > http://www.q-v-d.demon.co.uk/smsqe.htm
Hello, It is interesting to see that this was all done already in the past, see: http://www.inwap.com/pdp10/paper-smp.txt Also see this interwiew of Bill Gates and notice how he says that the PDP10 was a fantastic machine: http://americanhistory.si.edu/collections/comphist/gates.htm#tc4 That was when he was allowed to use a PDP-10 at nights, thus when he was about 12. Further research show that this early TOPS-10 "timesharing" single processor OS did work internally like the QL's QDOS. However UNIX was free within universities, hence was successfull, and Digital Equipment favored its VAX line of OSes, based on similar algorithms than UNIX. That lead them to the end within about 20 years. In the meantime Microsoft had grown enough with a ugly but _working_ monotasking system (MS-DOS it was named) and could hire a technical leader at DEC. Bill hired the chief designer of the VAX products which lead to NT, 2000, XP, Vista etc.. instead of those great developers of that fantastic Tops-10. The right technology was killed a second time. Sinclair Research and Tony Tebby came about 15 years after DEC and did reinvent the wheel but was not successfull either. As I am optimistic I think that the better technology wins in the end, but it must come at the right time (the story of gas vs electric engines in cars). So it must be reinvented many times. IMHO it is definitely not Linux... Happy new year Arnould _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
