Re: [Gems-users] Bit-level analysis of the on-chip messages

["Mike Marty" <mike.marty@xxxxxxxxx>]

GEMS doesn't care nor model the actual length of the fields.  We set the MessageSizeType and the actually number of fields and fall short or exceed this number of bytes specified

On Jan 17, 2008 12:19 PM, Lide Duan < leaderduan@xxxxxxxxx> wrote:

Thanks for the reply, Niket.

Actually I don't need the bit-level "values", but I want to know the bit length of each field in a message. For example, a control message possibly contains requester ID, destination ID, some flags, ect, and I am wondering how to know the bit length of each of these fields. In other words, I want to know the "format" of a message. As you mentioned, it depends on the protocol. To my understanding, GEMS treats a message as a "bulk" structure, i.e. it defines the contents of a message, but transmits it as a whole thing (8 bytes or 64+8 bytes). Am I right?

How does the new network model deal with the messages? Do you have any idea about this?

Thanks,
Lide

On 1/17/08, Niket < niketa@xxxxxxxxxxxxx> wrote:

Hi Lide,

The control messages are all 8 bytes but are dynamically casted
depending on the protocol. For instance, a request message might be a
token request in a token coherence protocol or an invalidation in a
directory protocol. You can figure that out  by  making minor modifications.

The data messages are basically 64 byte cache lines + 8 byte control
information. If you are looking for data values, I am not sure whether
Ruby carries the data values around. From what I understand, it is a
timing interface and hence cache line values do not fly around. I
remember reading some old posts mentioning that some previous version
had the interface but I am not sure it is any longer present.

But why do you need these bit-level values ? I presume you want to do
some power calculations ?

As regards the detailed network model inside GEMS, it should be out
pretty soon.

Regards,
Niket


Lide Duan wrote:
> Hi everyone,
>
> I am wondering if there is any bit-level configuration/analysis of the
> messages traversing across the on-chip network in GEMS. I notice that,
> for the various on-chip messages, GEMS specifies the control message
> as 8 bytes and the data message as 64+8 bytes, but I need more
> detailed information about what these bytes/bits should be. I also
> notice that, for each protocol, there is a file that specifies the
> message structures used in this protocol, but it does not contain the
> bit length information.
>
> Besides, I am also wondering when the next version GEMS that
> incorporates a detailed network model will be released. I am quite
> expecting it.
>
> Thanks,
> Lide
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