Re: mutex vs cache coherency protocol

Hi Robert,

could you explain more about it, I am quite interested in this.

thanks,

regards,

Yang


2007/9/3, Robert M. Hyatt <[email protected]>:
>
> what about the kernel?  How will it protect itself when multiple
> processors execute kernel code???
>
>
> Robert M. Hyatt, Ph.D.          Computer and Information Sciences
> [email protected]                   University of Alabama at Birmingham
> (205) 934-2213                  136A Campbell Hall
> (205) 934-5473 FAX              Birmingham, AL 35294-1170
>
> On Mon, 3 Sep 2007, Xu Yang wrote:
>
> > Hello everyone,
> >
> > Just got a rough question in my head.
> >
> > don't know whether anyone interested .
> >
> > mutex vs cache coherency protocol(for multiprocessor)
> >
> > both of these two can be used to protect shared resource in the memory.
> >
> > are both of them necessary?
> >
> > for example:
> >
> > in a multiprocessor system, if there is only mutex no cache coherency.
> > obviously this would cause problem.
> >
> > what about there is no mutex mechanism, only cache coherency protocol
> > in multiprocessor system? after consideration, I found this also could
> > casue problem, when the processors are multithreading processors,
> > which means more than one threads can be running on one processor. in
> > this case if we only have cache coherency and no mutex, this would
> > cause problem. because all the threads running on one processor share
> > one cache, the cache coherency protocol can not be functioning
> > anymore. the shrared resource could be crashed by different threads.
> >
> > then if all the processors in the multiprocessor system are sigle
> > thread processor, only one thread can be running one one processor. is
> > it ok, if we only have cache coherency protocol ,no mutex mechanism?
> >
> > anyone has any idea? all the comments are welcome and appreciated,
> > including criticism.
> >
> > regards,
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-smp" in
> > the body of a message to [email protected]
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>