Re: Regarding Dual core processors



On Mon, 19 Mar 2007 08:49:43 +0000, Chris Hills <chris@xxxxxxxxxxxx>
wrote:

In article <jo8sv299adbfscv6i7pmi58opvt2eii9ae@xxxxxxx>, Paul Keinanen
<keinanen@xxxxxx> writes
On Sun, 18 Mar 2007 18:16:59 -0600, Dennis <dennis@xxxxxxxxxxx> wrote:

Chris Hills wrote:

Well in most multi tasking systems there is only 1 MCU. And you time
slice. So many miliseconds per task to give the illusion of lots os
things happening at once.

The idea with the PC dual, quad core etc is that you really can have
several tasks in parallel. It can give a speed increase.

It is great fun to talk to Windows programmers who think that because
they have been "multi tasking" and "threading" for years that multicore
processors will just work. They will soon find out that the fact there
was only one real processor covered up a lot of concurrency and
synchronization bugs.

Motherboards with two or four x86 CPUs have been available since
1990's, mainly intended for server applications.

There is a difference between multi CPU/MCU and multipile cores onthe
same chip.

Could you, please, be a bit more specific about the implication on the
software design.

I have used multiprocessors based on 74Sxx TTL chips, ASICs, multiple
Pentiums (just writing this on such machine) and multicore processors
and I have not seen a reason, why I should program these differently.

I think it is important to realise, that in any virtual memory system,
any code/data memory access can cause a page fault, i.e. cause a page
to be loaded from the disk (slowly), thus, there can be a
process/thread switch between each memory access.

Paul

.