Re: mutex vs cache coherency protocol

["Xu Yang" <risingsunxy@xxxxxxxxxxxxxx>]

Hi Mohanmed,

thanks for you recommand, I have ordered this book.


2007/9/4, Mohamed Bamakhrama <bamakhrama@xxxxxxxxx>:
> On 9/3/07, Xu Yang <risingsunxy@xxxxxxxxxxxxxx> 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.
> >
>
> Hi,
> I advice you to read the following book:
> "UNIX systems for modern architectures: symmetric multiprocessing and
> caching for kernel programmers"
> C Schimmel - 1994 - Addison-Wesley Longman Publishing Co., Inc. Boston, MA, USA
>
> Best regards,
>
> --
> Mohamed
>
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