"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
See below...
even if the write occurs before the lock.
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I find this truly unbelievable. How can a mutex know what values were
accessed during the
thread, so that it can ensure the values are going to be consistent if
that same mutex is
locked? This strikes me as requiring immensley complicated bookkeeping on
the part of the
mutex implementation. It seems so much easier to follow the semantics of
most hardware
and just make sure that locking guarantees all pipes and caches are
coherent across all
processors. While I first find it hard to imagine how it is possible to
create a
situation of this nature on any closely-coupled MIMD architecture, I can
imagine how it
can exist in a distributed MIMD architecture, but in that case, the mutice
have to keep
track of every variable that is accessed within their scope, and ensure
that an attempt to
lock a mutex can ensure that all remotely-cached data is sent back and all
locally-cached
data is distributed out. An awesome task.
*****