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

["Lide Duan" <leaderduan@xxxxxxxxx>]

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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