Re: [Gems-users] How to config memory system

[Dan Gibson <degibson@xxxxxxxx>]

Fixed memory latency = fixed time to service any request, once it arrives at a memory controller (+/- 2 cycles, to add random noise).

If you want to make a NUMA system, you have to do it by adding long links between distant chips.

Regards,
Dan

On Sat, Apr 3, 2010 at 8:52 AM, Edward Lee <edwl202@xxxxxxxxx> wrote:

Hi Dan,

By fixed memory latency, do you mean even the SMP protocols (without
_m) with distributed memory controllers establish a UMA system not a
NUMA?

Thanks,

Ed

On Sat, Apr 3, 2010 at 10:43 AM, Dan Gibson <degibson@xxxxxxxx> wrote:
> 1. The number of memory controllers is a function of the network topology.
> They appear in the topology as "Directory Memory" objects. This is true
> regardless of whether you happen to be using a 'CMP' or 'SMP' protocol.
> 2. Memory controllers are shared by all processors.
> 3. In GEMS, Memory Controller = Memory Channel.
>
> Bonus extra response: Only protocols that end in _m actually use a realistic
> memory controller. All other protocols just assume memory has a fixed
> latency.
>
> Regards,
> Dan
>
> 2010/4/3 张轶 <zhangyi@xxxxxxxxxxxxxx>
>>
>> Hi, all
>>
>> Currently, I am using GEMS 2.1 to perform simulation and have some
>> confusions on memory configs:
>> 1. I am wondering, in GEMS how to set the numbers of memory controller for
>> CMP and SMP system? Is it the same in both CMP and SMP?
>>
>> 2. Will memory controller be shared by all processors?
>>
>> 3. Is memory controller the same thing to memory channels?
>>
>> Many thanks for your help!
>>
>> Zhang Yi
>>
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