Re: [Gems-users] L1 misses in MOESI_CMP_directory

["Yoav Etsion" <etsman@xxxxxxxxxxxxx>]

That is exactly the question I ran into when I started coding.

My conclusion is that in this case, an L1 miss should be defined as a 'non-hit',
which leads us to another question - what is a hit? two possible definitions:
1.
A hit is an access occurring when cache contains valid data, such that
any core request
can be served without requesting fresh data from an external entity -
another L1, L2,
directory - but at a possible need for a permissions upgrade.
This is a simple definition since hits/misses only depend on the state
of the block and are
not access dependent. In addition, insertions and eviction can be
defined as transitions
to/from states containing a valid block.

2.
A combination of State/Event that allow the cache to respond immediately
without having to turn to an external entity.
This definition is more complex as it depends on the access type, therefore
a valid cached block may produce either a hit or a miss, depending on
the access.
This makes insertions/evictions harder to define as well.

The realization that this is basically an arbitrary choice lead me to
go with the simpler
definition, basically using a subset of all states as 'hit' states,
such that any transition
that involves a state outside this subset is considered a miss
(the 'hit' states are S, O, M, M_W, MM, MM_W, SM, OM).

But since you guys are the experts, I'd really appreciate your input
on that matter :-)

Thanks,

Yoav


On Nov 19, 2007 2:43 AM, Dave Z. <zhu_dave@xxxxxxxxx> wrote:
> Hi,
>
>
> The profileMiss actions are commented out in MOESI_CMP_directory-L1cache.sm. If we try to profile the L1 misses, the assertion in profile_miss - RubySlicc_Profiler_interface.C fails. What would be a good way to profile L1 misses in CMP protocols?
>
>
> Thanks,
>
>
> Dave
>
>
>
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